Profitable Farming of Beef Cows - Beef + Lamb New Zealand

Profitable Farming 

of Beef Cows 

Editors: Steve Morris 

and Duncan Smeaton 

2009

Profitable Farming of Beef Cows 

Steve Morris and Duncan Smeaton

Profitable Farming of Beef Cows 

Written by: 

Steve T. Morris, Massey University, Palmerston North, New Zealand and 

Duncan C. Smeaton, AgResearch, Ruakura Research Centre, Hamilton, New Zealand 

Special thanks are expressed to the following writers who also contributed: 

John Meban, Veterinarian, Gisborne part Chapter 4 

Chris Morris, AgResearch, Ruakura 

sundry technical advice and accuracy checks 

part Chapters 2 and 4; 

David Wells, AgResearch, Ruakura part Chapter 4 

John Pickering, Veterinarian, Whanganui part Chapter 5 

Dorian Garrick, Massey University part Chapter 6 

Kevin Stafford, Massey University Chapter 7 

Editorial team: 

Duncan Smeaton, Andy Bray, John Meban, Steve Morris, John Journeaux, 

Peter Packard, Russell Priest 

Printed by: Fusion Print Group Limited, Hamilton 

Copyright © NZ Beef Council

Preface 

Professor Steve Morris from Massey University and Beef Production Scientist from 

AgResearch, Duncan Smeaton, have, in this book, put together what could be rightfully 

considered the New Zealand Manual for Beef Cow farming. So complete, thorough and 

practical is it that both experienced farmers and new farmers embarking on the bovine 

trail will find it as a guiding gospel, complete in its wisdom and forthright in the knowledge 

it contains. 

Until lately the beef cow has been unable to show just how valuable and profitable she 

truly is. Devoted farmers of beef cows of all breeds have known by good old “seat of your 

pants” farming that these Queens of the hills have been an integral part of the overall 

profitability of their farms. It has been largely due to the eight Beef Focus Farms, in a 

project financed by Meat and Wool New Zealand, and the work of the facilitator Duncan 

Smeaton and his group of scientists from AgResearch, that we now have figures to prove 

just how well farmed cows and the relevant backup cattle, have guarded and increased 

the profit of sheep and other stock classes that farm with them. They often do this by 

eating some of the best feed available, but more often eating the very worst feed 

available too. 

The ongoing desire to eat better tasting beef here in New Zealand and supply a better 

tasting product to our customers abroad will continually require our beef farmers to have 

expectations of both stock and land that will be hard to fulfil. Confidence that what they 

are doing is both technically and financially sound will be a big part in achieving this, and 

Steve and Duncan and their teams have surely provided a very important footing. 

The New Zealand Beef Council had no hesitation in helping sponsor the publication of 

this book as an effort in overcoming the somewhat alarming decline in beef cow numbers 

being farmed in New Zealand. Although at the time we were not in complete knowledge 

of all the data that the focus farms were producing, we felt that as beef cows were the 

lynch-pin of the prime beef industry they needed some up-to-date reference material for 

use by many sections of the farming industry as well as a reference for teaching. 

As with most agricultural sciences in the modern world, beef breeding is a moving target 

and improvements and refinements come upon us at a sometimes alarming rate. I’m sure 

that before too long some of the methods referred to here will have been updated and 

brought into line with what-ever edict is coming down the pipe. I am equally sure that the 

vast amount of learning this publication has to offer can be relied upon as sound science 

for many years to come. 

John Wauchop, Chairman, NZ Sheep and Beef Council and Meat & Wool New Zealand. 

January 2009 

Note to Readers: 

There are 2 condition score (CS) systems in place for recording beef cow body condition or 

fat cover. One system operates on a 0 (emaciated) to 5 (fat) scale, the other system 

operates on a 1 (emaciated) to 10 (fat) scale. The systems are described in the book. 

Whenever CS is discussed in the book, the value for the first system is noted, followed by 

the value for the second system in brackets. For example, CS 2.0 (4).

Table of Contents 

i 

Chapter 1: Introduction ......................................................................................................... 1 

Summary ........................................................................................................................... 1 

1.1. The importance of the breeding cow to the beef industry ....................................... 2 

1.2. Beef breeding cow herds ...................................................................................... 4 

1.3. Breeding cows versus other sheep/beef enterprises ............................................. 7 

1.3.1 Key points ........................................................................................................ 7 

1.3.2 High vs. average performance cows ................................................................. 7 

1.3.3 Simplistic calculation of enterprise biological and gross margin performance .... 8 

1.3.4 Calculating the full value of breeding cows on sheep and beef farms ................ 9 

1.4. Beef herd sizes ................................................................................................... 13 

1.5. Further reading ................................................................................................... 14 

Chapter 2: Weight of calves weaned and cow efficiency ..................................................... 15 

Summary ......................................................................................................................... 15 

2.1 Introductory comments ....................................................................................... 16 

2.2 Setting and achieving calving date and calf weaning weight targets .................... 16 

2.3 Optimum cow liveweight and cow efficiency ........................................................ 18 

2.4 Genetic selection for cow efficiency .................................................................... 19 

2.5 Other pathways to cow efficiency ........................................................................ 21 

2.6 Cow liveweight and pasture damage ................................................................... 21 

2.7 Weaning date, calf age at weaning ..................................................................... 22 

2.8 Further reading ................................................................................................... 23 

Chapter 3: Feeding beef cattle............................................................................................ 24 

Summary ......................................................................................................................... 24 

3.1 Introduction ........................................................................................................ 25 

3.2 Energy requirements of cattle ............................................................................. 25 

3.2.1 Requirements for maintenance ....................................................................... 26 

3.2.2 Requirements for pregnancy ........................................................................... 27 

3.2.3 Requirements for lactation and calf growth ..................................................... 28 

3.2.4 Liveweight loss or gain ................................................................................... 29 

3.3 Calculating feed requirements ............................................................................ 30 

3.4 Management and nutrition of the beef cow .......................................................... 31 

3.4.1 General comments ......................................................................................... 31 

3.4.2 Post-weaning (weaning through to 4-6 weeks pre-calving) .............................. 31 

3.4.3 Pre-calving (from 4-6 weeks pre-calving to calving) ........................................ 32 

3.4.4 Calving to mating ............................................................................................ 33 

3.4.5 Mating - weaning ............................................................................................ 35 

3.5 Matching nutritional requirements to the seasonal pasture supply pattern ........... 35 

3.6 Supplementary feeding of beef cows .................................................................. 36 

3.7 Assessing the adequacy of feeding ..................................................................... 38 

3.8 Condition scoring ................................................................................................ 39 


Chapter 4: Reproduction in the beef cow herd .................................................................... 42 

Summary ......................................................................................................................... 42 

4.1 Introduction ........................................................................................................ 43 

4.2 Potential reproductive rate .................................................................................. 45 

4.3 Reproductive management of beef cattle ............................................................ 49

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4.3.1 Management and age at first calving of heifers ............................................... 49 

4.3.1.1 Critical minimum weight ......................................................................... 52 

4.3.1.2 Checklist for successfully mating heifers at 15 months ........................... 52 

4.3.2 Time and duration of calving ........................................................................... 53 

4.3.3 Age of cow and reproductive performance ...................................................... 54 

4.3.4 Calving difficulty (dystocia) ............................................................................. 55 

4.3.5 Post-partum anoestrus interval ....................................................................... 58 

4.3.6 Bull management ........................................................................................... 60 

4.3.7 Pregnancy diagnosis ...................................................................................... 62 

4.3.7.1 Two methods of pregnancy diagnosis ..................................................... 62 

4.4 New reproductive technologies for use in beef breeding cows ............................. 63 

4.4.1 Oestrus synchronisation ................................................................................. 64 

4.4.2 Artificial insemination (AI) ............................................................................... 64 

4.4.3 Producing twin pregnancies ............................................................................ 65 

4.4.4 Changing average calf sex ratio ...................................................................... 66 

4.4.5 Cloning ........................................................................................................... 67 

4.4.6 DNA parenting ................................................................................................ 67 


Chapter 5: Cow health ......................................................................................................... 70 

Summary ......................................................................................................................... 70 

5.1 Grass staggers (Hypomagnesaemia) .................................................................. 71 

5.1.1 Overview ........................................................................................................ 71 

5.1.2 Magnesium supplementation .......................................................................... 72 

5.2 Facial eczema .................................................................................................... 75 

5.3 BVD in beef cattle ............................................................................................... 76 

5.3.1 Persistently Infected (PI) animals .................................................................... 76 

5.3.2 How does the virus affect cattle? .................................................................... 77 

5.3.3 Control of BVD ............................................................................................... 78 

5.4 Nitrate poisoning................................................................................................. 79 

5.5 Bloat ................................................................................................................... 79 

5.5.1 Overveiw ........................................................................................................ 79 

5.5.2 Management measures to reduce the risk of bloat .......................................... 80 


Chapter 6: Genetics of calf production from beef cows ........................................................ 81 

Summary ......................................................................................................................... 81 

6.1 Introduction ........................................................................................................ 82 

6.1.1 Selection decisions ......................................................................................... 84 

6.2 Selection objectives ............................................................................................ 87 

6.2.1 Breeding objectives ........................................................................................ 87 

6.2.2 Economic weights and values ......................................................................... 88 

6.2.3 The importance of future prices ...................................................................... 88 

6.2.4 Selection criteria ............................................................................................. 89 

6.3 Estimated Breeding Values (EBVs) ..................................................................... 90 

6.3.1 Growth EBVs .................................................................................................. 91 

6.3.2 Reproduction EBVs ........................................................................................ 92 

6.3.3 Carcass EBVs ................................................................................................ 93 

6.3.4 Additional EBVs available ............................................................................... 94 

6.3.5 Accuracy of EBVs ........................................................................................... 95 

6.3.6 Profitable use of EBVs .................................................................................... 96 

6.4 Index Selection (BreedObject) ............................................................................ 97 

6.4.1 Angus BreedObject ........................................................................................ 98 

6.4.2 Hereford BreedObject ..................................................................................... 99 

6.5 Selecting breeding females ............................................................................... 100 

6.6 Evidence of genetic progress ............................................................................ 102

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6.7 Choice of breed ................................................................................................ 103 

6.8 Breeding systems ............................................................................................. 107 

6.9 Crossbreeding .................................................................................................. 108 

6.9.1 Alternative crossbreeding systems................................................................ 109 

6.9.2 Composite breeds ........................................................................................ 112 

6.9.3 Alternating breeds over time ......................................................................... 112 

6.9.4 Benefits of crossbreeding ............................................................................. 112 

6.9.5 Disadvantages of crossbreeding ................................................................... 113 

6.10 Further reading ................................................................................................. 114 

Chapter 7: Beef cattle handling and yarding ..................................................................... 116 

Summary ....................................................................................................................... 116 

7.1 Introduction ...................................................................................................... 116 

7.2 Cattle handling: Moving cattle .......................................................................... 117 

7.3 Working in yards ............................................................................................... 118 

7.4 Using forcing pens ............................................................................................ 119 

7.5 Working in races ............................................................................................... 120 

7.6 Yard design ...................................................................................................... 121 

7.7 Conclusions ...................................................................................................... 122 

7.8 Further reading ................................................................................................. 122 

Appendix 1: Condition scoring (CS) for beef cows ............................................................ 123 

Appendix 2: Nutrient composition of commonly available feeds for cattle and sheep ......... 128

Summary 

1 

Chapter 1: Introduction 

The beef cattle industry in New Zealand is made up of 4.3 million cattle of which 

1.13 million (2008) are breeding cows. Traditionally, the New Zealand beef herd has been 

based upon calves produced by breeding cows. An alternative system involves purchasing 

4-day-old calves from the dairy herd and raising these as bulls or sometimes steers for 

slaughter, or as replacement heifers in the beef breeding herd. 

Achievable production objectives for a commercial beef breeding cow herd are to: 

Rear to weaning 90-95 calves per 100 cows mated each year for 63 days or less 

Grow suckling calves at greater than 1.0 kg/head/day 

Maintain a low death rate in the cow herd (2 to 3% per annum) 

Use the breeding cow herd to promote and maintain pastures. 

At an assumed national average calving percentage (calves weaned/cows mated) of 80%, 

the beef cow requires around 16 kg of dry matter per kg of calf weaned. The average beef 

cow produces 0.30 kg calf weaned/kg cow weaning weight. In contrast, a high performing 

cow produces 0.48 kg calf weaned/kg cow weaning weight (calculated as a 450 kg cow 

weaning 92% calves per cow mated, with calves growing at 1.1 kg/calf/day for 180 days) 

and is more profitable. Very few farmers get all the components of high cow productivity 

right all the time. Clearly it is a difficult business. 

Breeding cows are often seen as being less profitable than other stock but this usually 

excludes the effects of the beef cow on pasture quality. Recent results have shown that for 

much of the year, many breeding cows consume poor quality herbage which is of little or no 

value to other stock classes. On this poor quality feed, cows are more profitable than other 

live stock classes. Other benefits include lower labour requirements. The cow needs to 

play a complementary rather than competitive role to maximise these extra benefits. If a 

farm produces only high quality pasture, then the pasture management benefits from cows 

are likely to be low. 

Profitable Farming of Beef Cows Chapter 1: Introduction

2 

Beef herd sizes are highly skewed because many small holdings (lifestyle blocks) run just a 

few beef cattle. About 45% of beef cattle farms have less than 50 cattle and account for 

only 7% of total beef cattle. At the other extreme, 6% of farms have over 500 beef cattle. 

In aggregate, these farms hold 41% of the total beef cattle. 

1.1. The importance of the breeding cow to the beef industry 

The beef cattle industry in New Zealand is based on a national herd of around 4.3 million 

cattle. Considerable variation in the size of the national beef herd has occurred over the last 

two decades. Beef cattle numbers peaked at 6.3 million in 1975 then subsequently 

declined to 4.5 million in 1983. Currently (2008) the national beef breeding cow herd 

numbers 1.13 million. 

In New Zealand beef cattle and sheep are usually farmed together, and are complementary 

to one another especially under hill country conditions. It is relatively easy for producers to 

alter their mix of sheep and cattle to suit current economic conditions and preferences. The 

main driving force behind this substitution is the relative profitability between cattle and 

sheep. Growth in beef cattle numbers has occurred since 1983 but numbers today are 

relatively static at around 4.5 to 5.0 million with fluctuation being mainly due to changes in 

the number of dairy and dairy beef cross calves reared for beef production. 

Traditionally, the New Zealand beef herd has been based upon the beef breeding cow 

producing calves. Normally bull calves are castrated and raised as steers for slaughter 

either on breeding or finishing farms. The latter are usually located on better class country. 

Heifer calves replace the old and cull cows within the breeding herd and those that fail to 

get pregnant. While this management system is practised around the country an alternative 

system using calves from the dairy herd has come into prominence. Four-day-old calves 

are purchased from the dairy herd and raised as bulls or sometimes steers for slaughter. 

Beef breed x Friesian heifers are raised for replacements in the beef breeding herd. The 

advantages for the bull system are two-fold. Firstly, there is no capital overhead tied up in a 

beef-breeding herd, so more capital can be used for direct income generation. Secondly, 

relatively more feed goes into production than maintenance, making this system more 

efficient. Needless to say, some traditional beef cow herds are also very efficient. 


3 

During the spring of the 2006 season the number of dairy calf retentions for beef production 

was estimated at around 529,000, equivalent to around 38% of the total calves entering the 

beef herd. 

With an increasing percentage of the New Zealand beef herd being derived from the dairy 

herd, the ratio of beef breeding cows and heifers in the national herd has declined from 

36% in 1972-1973 to 27% in 2007-2008 with a resultant increase in “trading” or finishing 

stock (see Table 1.1 where they are classified as “other cattle”). Unless retention of female 

beef stock numbers increases, future growth and annual fluctuations in beef cattle numbers 

will primarily be due to the number of dairy calves originating from the dairy industry that 

are reared for beef production. 

Another likely reason for the decline in breeding cow numbers is due to their perceived 

poorer profitability. On a gross margin / kg DM basis, they are less profitable, but this 

excludes the effects of the beef cow on pasture quality. In fact, the breeding cow is 

significantly more profitable than other stock classes on poor quality feed. The cow needs 

to play a complementary rather than competitive role to maximise these extra benefits. 

About 78% of New Zealand’s beef herd is located in the North Island. While relatively 

evenly distributed throughout the North Island, the Northland//Waikato/Bay of Plenty region 

has 35% of the total herd. Table 1.2 lists the major beef cattle producing regions. A recent 

change in cattle numbers is occurring in the lower part of the South Island where 

substantial numbers of dairy beef calves are now being sourced from the increasing 

number of dairy farms in the region. 


Table 1.1: Composition of the New Zealand beef herd (000) (as at 30 June). 

Year 1973 1993 2008 

Total Beef Herd 5,343 4,676 4,253 

Breeding Cows 1,907 1,419 1,126 

Other Cattle 3,436 3,257 3,127 

Breeding cows as 

% of total 

36 30 27 

Source: Meat & Wool New Zealand Economic Service. 

Table 1.2: Beef cattle numbers by local region (as at 30 June 2008) 

4 

Region Number of Beef Cattle (000) % of Total Cattle 

Northland/Waikato/BOP 1,489 35 

East Coast 1,060 25 

Taranaki/Manawatu 509 12 

NORTH ISLAND 3,058 72 

SOUTH ISLAND 1,196 28 

NEW ZEALAND 4,253 100 

Source: Meat & Wool New Zealand Economic Service, paper P08031 25 July 2008. 

1.2. Beef breeding cow herds 

The breeding cow herd is dominated by two breeds, the Angus and Hereford. The heavier 

European breeds began to be imported in the late 1960's and some, especially Simmental, 

Charolais, South Devon and Limousin have made an impact as terminal sires, where, with 

rare exceptions all progeny (both male and female) are sold for slaughter or to finishing 

farms. There has also been an increased use of beef x dairy breeding cows to take 

advantage of Friesian genes for higher milk and beef production. It is estimated (2007) that 

the national herd consists of 23% Angus, 11% Hereford and 11% Hereford x Angus. Angus 

and Hereford crosses would also contribute to a group classified as mixed crosses (36%) 

while Friesian cross (12%) and others (7%) make up the rest (derived from data from 

Meat & Wool New Zealand Economic Service). 


Achievable objectives for a commercial beef breeding cow herd are to: 

5 

Rear to weaning 90-95 calves per 100 cows mated each year for 63 days or less 

Grow suckling calves at greater than 1.0 kg/head/day 

Maintain a low death rate in the cow herd (2 to 3% per annum) 

Use the breeding cow to promote and maintain pasture quality 

The national average calving rate (the number of calves weaned as a % of cows mated) is 

82% (range 79% to 86%) and has remained at this level for the last 35 years. Age of first 

calving is usually 3 years although approximately 30% of all heifer replacements now calve 

at 2 years of age. The top third of herds in any year have an average 90% calving rate or 

better. There is potential for increased reproductive performance of the beef herd within the 

constraint of a natural ovulation rate of 1.0 in cattle. 

Because the overall output of a breeding cow herd is dependent on both weaning 

percentage and weaning weight of the calf, these are often combined into a term called cow 

productivity. 

Productivity = 

no. of calves weaned x Av. weaning weight 

no. of cows joined with bull 

However, the total feed consumed by large cows is greater than that of small cows. To 

take account of this the term weight of calf weaned per cow joined (i.e. the productivity) 

divided by the cow liveweight (usually autumn or weaning weight but some farmers prefer 

to use winter liveweight) is a commonly used measure of biological efficiency in the beef 

breeding cow herd. 

Efficiency = 

Productivity 

Cow liveweight 

As a general rule, smaller cows that wean heavy calves (in excess of 50% of their dam 

autumn liveweight) are more efficient. This is probably easier to achieve with some form of 

crossbreeding where a larger terminal sire breed is crossed with a smaller dam breed. 

The difference in annual feed consumption (kg dry matter/head/year) for three different cow 

liveweight types (small, medium and large) means small cows rearing small calves can be 

just as efficient and profitable as large cows rearing large calves. Table 1.3 illustrates that 

there are a range of cow types that can give similar productivity and returns. If each of the 

cows in Table 1.3 rears 50% of their own autumn liveweight to sale as weaner calves they 


6 

are then all equal in terms of $ return per kg of feed eaten or per stock unit. It is high 

productivity irrespective of cow size that makes a beef cow herd profitable 

Table 1.3: Seasonal liveweights and production data for three different beef breeding 

cow types and calculations of efficiency and profitability (note liveweights exclude the 

weight of conceptus). The calculations assume that small vs. large weaners are worth the 

same per kg liveweight. 

Small Medium Large 

Weaning (kg) 430 470 550 

Mid-winter (kg) 380 420 500 

Pre-calving (kg) 380 420 500 

Mating (kg) 410 450 530 

Calf wean wt (kg) 215 235 275 

Feed eaten per cow (kg DM) 2880 3131 3657 

Number of cows 100 92 79 

Number of calves 

(at 80% CW/CM*) 

80 73.6 63.2 

Kg DM/kg Calf weaned 16.7 16.8 16.6 

Return/kg feed ($) 0.186 0.187 0.187 

Gross margin ($ / SU) 105 107 108 

* Calves weaned per cows mated. 

If a beef cow herd is not productive then the other benefits of keeping this class of stock 

need to be large to compensate (i.e. improved sheep performance). These other benefits 

have proven difficult to quantify although recent trial results described below provide more 

information. 


1.3. Breeding cows versus other sheep/beef enterprises 

1.3.1 Key points 

7 

In single enterprise analyses comparing profitability of breeding cows, finishing 

cattle and breeding ewes, breeding cows usually appear less profitable. However, 

this analysis does not take into account the other benefits cows may provide within 

the farm system. 

Cows can play a valuable complementary role in managing pasture quality on sheep 

and beef farms but this is difficult to value. Results from the recently completed 

Meat & Wool New Zealand Beef Focus Farm project have shown that for much of 

the year, many breeding cows consume poor quality herbage which is of little to no 

value to other stock classes. On this poor quality feed, cows are more profitable 

than other live stock classes. Other benefits include less labour requirements. 

1.3.2 High vs. average performance cows 

Accumulated figures for breeding cows on New Zealand hill country farms (Meat & Wool 

New Zealand Economic Service) indicate that the average beef cow herd is performing well 

below potential in that: 

80 to 82 calves are weaned per 100 cows mated 

Calves grow at a little over 0.8 kg per day from birth to weaning (accurate figures 

not available) 

0.30 kg calf weaned/kg cow liveweight is produced (calculated as a 500 kg cow 

weaning 82% calves per cow mated, with calves growing at 0.90 kg/calf/day for 

180 days) 

The above implies that one in five cows are non productive, and the pasture these animals 

consume therefore represents a lost opportunity. This is partially offset if farmers cull empty 

cows at weaning but this has an added cost in terms of higher replacement rates. 


8 

In contrast, high producing cows in the recent Beef Focus Farm Project funded by 

Meat & Wool New Zealand (2008): 

Weaned in excess of 92 calves per 100 cows mated 

Grew their calves at 1 to 1.2 kg/head/day from birth to weaning 

Produced 0.48 kg calf weaned/kg cow weaning weight (calculated as a 450 kg cow 

weaning 92% calves per cow mated, with calves growing at 1.1 kg/calf/day for 

180 days). 

Were more profitable (Table 1.4). 

High performing cows are often beef x dairy cross cow mated to a terminal sire thereby 

taking advantage of hybrid vigour. In this system, all calves are finished for beef, with 

replacements sourced from outside the herd. 

Trial results indicate that the high levels of performance described above are routinely 

achieved on some farms with the cow still carrying out her complementary role of pasture 

management, provided the cow can regain any lost weight during the crucial calving to early 

mating period. Even so, very few farmers get all the components of high cow productivity 

right all the time. Clearly it is a difficult business. The prioritisation of other stock classes 

over breeding cows is often the root cause of poor cow performance. Farmers who achieve 

high levels of cow performance while using cows for pasture management have learnt the 

critical elements that allow these two conflicting goals to be met. 

1.3.3 Simplistic calculation of enterprise biological and gross margin 

performance 

When various sheep and beef systems are compared on a single enterprise basis, results 

such as shown in Table 1.4 can be derived. 


9 

Table 1.4: Comparison of four single-enterprise systems modelled using Farmax, each 

on the same pasture growth curve. 

Average ** 

performance 

cow 

High ** 

performance 

cow 

High 

Fertility 

ewe 

1yr bull 

system 

GM* $/ha 449 680 717 796 

GM c/kg DM 6.6 8.9 8.6 10.7 

Net LWG/ha 350 490 591 908 

kg DM/kg LWG 20 16 13 8 

* Gross Margin 

** As described in section 1.3.2 

Average performing beef cows are less productive and profitable than some other 

enterprises largely because of their high maintenance requirement and the apparently 

non-productive period from weaning to just before calving in terms of product gain/kg DM 

eaten. If cows could rear and wean two calves via twin pregnancy that would cause a 

quantum leap in productivity and probably profit, but that is mostly outside current 

technology. Table 1.4 demonstrates that finishing systems, such as the bull system shown, 

are more efficient biologically, and also currently more profitable. High fertility ewes are 

also relatively efficient, and are often very competitive financially. 

However, the above gross margin analysis can be misleading because it takes no account 

of the complementary role that one stock class provides for another within a full farm 

system. 

1.3.4 Calculating the full value of breeding cows on sheep and beef farms 

It is generally recognised that cows play an important role in maintaining pasture quality on 

many farms, benefiting other live stock. Cows can also lose a lot of weight during poor 

winters, freeing up feed for other less resilient stock. This effect was studied in the recent 

Beef Focus Farm Project funded by Meat & Wool New Zealand (2008). On the Northland 

farm in this project, cows spent summer, autumn and winter cleaning up behind other live 

stock. The quality of the pasture being consumed by the cows was monitored on a monthly 

basis for the cows, and for the other stock the cows were complementing. On one of the 


10 

blocks on the farm, the cows predominantly grazed on medium to steep hill land (with 

approximately one quarter of the pasture having a Kikuyu base) and the cows followed 

behind ewes and lambs. The other block was rolling to medium hill land with approximately 

90% of the pasture Kikuyu based and cows grazed among young cattle. 

The grazing residual results showed that the cows were restricted most, during 

summer/autumn and early winter, when they were cleaning up behind the other stock 

classes (Figure 1.1) but that in spring, they fared much better. 

Figure 1.1: Average post-grazing herbage mass of breeding cows and other stock 

classes (Northland Focus Farm). 

In general, the quality (MJ ME/kg DM) of pasture offered to the cows was poorer than that 

grazed by the other live stock (Figure 1.2). The quality of the diet offered to the cows 

changed with season to a greater extent than that of the other live stock classes, reflecting 

the ability of management to prioritise better quality feed to other live stock classes during 

seasons when poor quality feed was present (summer and autumn). Over the 3 years of 

the study, the average metabolisable energy concentration (ME) of pasture consumed by 

cows was 8.8 vs. 10.3 MJ ME/kg DM for the other stock classes the cows were 

complementing. 


11 

Figure 1.2: Average metabolisable energy content of pasture offered to the breeding 

cows and other livestock classes. 

Cow liveweights and condition score peaked during summer in response to good feed 

availability during spring and early summer (Figure 1.3) and declined again during late 

summer and autumn. Despite the poor quality of feed and loss in cow liveweight, each year 

the calves grew at greater than 0.6 kg/day during the late summer/autumn period and 

greater than 0.8 kg/day over the whole lactation period. This demonstrates the ability of the 

cow to buffer the calf, through liveweight loss and milk production during this period on poor 

quality pasture. 

Figure 1.3: Average cow (conceptus-free) liveweight and condition score (on a 1 – 10 

scale). 

Observations on a second focus farm in the same project as reported above, in Southland, 

showed similar buffering effects by the cow. 


12 

If the poor quality herbage is not consumed by cows then it either will be consumed by 

another stock classes or it will decay. In the Focus Farm Project, the former option was 

tested using the computer models Q-Graze and Farmax (see Further Reading). The weight 

gain or loss of 2-year-old bulls fed the same quality of pasture as the cows was calculated. 

As with the breeding cows, the 2-year bulls were predicted to gain weight during spring and 

early summer and then lose weight during autumn and early winter (Figure 1.4). 

Figure 1.4: Estimated two year bull liveweight gain (kg/head/day) if fed on the same 

herbage as the breeding cows on the Northland farm, as calculated by Q-Graze. The 

change in value of 2-year bulls ($/head/day) is based on liveweight change and seasonal 

store market values. 

Total liveweight gain by the bulls for the year was calculated at only 38 kg. The analysis 

showed a total annual increase in bull value of $128 per cow equivalent. In contrast, cows 

were calculated to be returning $363 per head (after losses). That is, the cows returned a 

gross margin income of $235/cow more than the bull equivalent system could have done on 

the same feed. A similar exercise on the Southland farm showed a similar result. 

No one would normally farm finishing animals in the way shown above, but it does illustrate 

the fact that the pasture that the cows are consuming has very little value to other live stock 

classes for a large portion of the year. In fact there are times when this herbage could be 

considered a liability rather than an asset. 


13 

If a farm produces only high quality pasture, (though intensive subdivision etc) then the 

above benefits due to running cows are likely to be much less and returns will be closer to 

the enterprise results in Table 1.4. In this situation, cows should be replaced by higher 

return stock classes. However, it should be noted that intensive subdivision is not feasible 

on many hill country farms. 

1.4. Beef herd sizes 

Beef herd sizes are highly skewed because of the many small holdings (lifestyle blocks) 

which run a few beef cattle. Figure 1.5 shows that small holdings make up the majority of 

farms with beef cattle. However, these small holdings have a relatively small proportion of 

the total beef herd. For example, 22% of the beef holdings have less than 10 beef cattle. 

In aggregate, these holdings have just over 1% of the total beef cattle. About 45% of beef 

cattle farms have less than 50 cattle and account for only 7% of total cattle. This group of 

farms are likely to be less responsive to industry conditions than the larger more 

commercial farms. At the other extreme, 6% of farms have over 500 beef cattle. In 

aggregate, these farms have 41% of the total beef cattle. 

Figure 1.5: Beef cattle herd size distribution by % of cattle and % of farms, June 2002 

Source: Statistics New Zealand (2002) Agricultural Production Census – Note that this is 

the most recent information available. 


1.5. Further reading 

14 

AgResearch. 2002. In “Pasture quality: Principles and management, The Q Graze Manual. 

A reference document to accompany The Meat New Zealand pasture quality 

workshops, Published January 2002 Meat New Zealand, PO Box 121, Wellington, 

pp 1-26. 

Farmax. A decision support model for livestock farms. www.farmax.co.nz 

Marshall, P.R.; McCall, D.G.; Johns, K.L. 1991. Stockpol: A decision support model for 

livestock farms. Proceedings of the New Zealand Grasslands Association. 53: 

137-140. 

Meat & Wool New Zealand Economic Service. Various reports, available on 

www.meatandwoolnz.com 

Smeaton, D.C. 2003. Profitable Beef Production. A guide to beef production in 

New Zealand. Published by the New Zealand Beef Council. ISBN: 0-473-09533.5. 

Smeaton, D.C.; Boom, C.J.; Archer, J.A.; Litherland, A.J. 2008. Beef cow performance and 

profitability. Proceedings of the 38 th seminar of the Society of Sheep and Beef 

Cattle Veterinarians NZVA, pp 131- 140. 


Summary 

15 

Chapter 2: Weight of calves weaned and cow efficiency 

The total weight of calves weaned is the key production output of the breeding cow herd 

and is the end result of many input factors. About 70% of the variation in weaning weight of 

calves is due to differences in milk production of the dam. To achieve high calf weaning 

weights cows must be well fed before and after calving. A high level of feeding after calving 

is also necessary for a high conception rate at rebreeding. Date of weaning should depend 

on feed supply. 

The best cow for hill country is a medium sized cow that weans a high proportion of its 

liveweight in calf weaning weight. The optimum liveweight of mixed-age Hereford x Friesian 

cows is estimated to be 430 to 450 kg at mating. In a trial, cows at optimum weights, and 

rearing a live calf, weaned calves at 180 days of age that were 52% of their mother’s 

liveweight at mating. Including losses due to empty cows and calving losses, the ratio 

dropped to 44%. The average rate of calves weaned per cow mated in this case was 82%. 

Selecting to improve the efficiency of feed conversion in a cow herd has been proposed as 

an alternative to selecting for growth rate. Feed conversion ratio is a measure of the 

amount of feed eaten per unit of bodyweight gain or carcass weight gain. Net feed 

efficiency refers to variation in feed intake between animals beyond that related to 

differences in growth and liveweight. Selection for this should reduce herd feed costs. 

Ranking animals on net feed efficiency requires measuring differences in their feed intake, 

liveweight and growth rate over a defined test period. 

Selecting cows for lifetime productivity at first weaning can be advantageous but requires 

tagging of calves with their birth mothers. The process is complex, but the gains are there if 

farmers are willing to invest the time. 

Efforts have been made to improve cow productivity through multiple suckling via one 

means or other, but commercial success remains elusive because of technical and 

biological limitations. In the meantime, the best objectives are to run cows at optimum 

weights, take maximum advantage of their ability to gain and lose weight to support milk 

production and to maintain pasture quality, achieve high pregnancy rates and survival and 

take maximum advantage of genetic opportunities and hybrid vigour. 

Profitable Farming of Beef Cows Chapter 2: Weight of calves weaned and cow efficiency

2.1 Introductory comments 

16 

The total weight of calves weaned by the herd is a key production output of the 

breeding cow herd. 

It is a reflection of: 

Reproductive success; clearly, empty cows do not wean a calf 

Feeding levels of cow and suckled calf 

Cow and calf genetics, hybrid vigour 

Cow and calf health 

Age at weaning (for comparative purposes, a standardised weaning age of 180 days 

is often used). 

The weaning weight of an individual calf from a cow is dependent on the above factors and 

also more specifically: 

Cow milk production (in turn dependent on numerous factors) 

Age of dam 

Age of calf at weaning, affected in turn by: 

Calving date 

All the above are discussed in the various chapters of this book. The material below 

discusses management aspects of integrating these factors. 

2.2 Setting and achieving calving date and calf weaning weight targets 

The ability to wean heavy calves has become progressively more important in conventional 

single-suckled breeding-herds because of the trend towards selling cattle for slaughter at a 

younger age. This means that growth to weaning represents a higher proportion of total 

growth to slaughter. 

Calf weaning weight targets will be specific to the farm in question but a minimum liveweight 

gain target for a suckled calf on hill country should be 1.0 kg/calf/day. Typically in 

New Zealand it is less than this, particularly if the cow is expected to do a lot of pasture 

quality management work. Most beef calves are weaned at around 5 to 7 months of age 

resulting in calf weaning weights in the range of 180 to 240 kg (assuming a 35 kg birth 

weight). Some farmers achieve weights of up to 280 kg/calf. The importance of a 

condensed calving (target of 70% of cows calving in the first 21 days of calving) within an 


17 

appropriate calving period (where the planned start of calving is synchronised with pasture 

supply) cannot be underestimated because of its effect on calf weaning weight and cow rebreeding 

performance. Many commercial beef herds calve too early in the spring. The 

usual sign for this is a slow start to calving (less than 50% calved in the first 21 days of 

calving) which compromises calf weaning weights and cow rebreeding performance. 

The rate of growth of the suckling calf largely depends on the cow’s milk supply, which in 

turn depends on the food available to the cow. Some research suggests that about 70% of 

the variation in weaning weight of calves is due to differences in milk production of the dam. 

A calf can consume 10-15% of its liveweight as milk each day. A 50 kg calf can drink 7-8 kg 

milk per day and at this rate will grow at 1.0 kg liveweight gain/day. As the calf grows, its 

capacity to drink milk increases and there are obvious advantages if the cow can increase 

her milk production to match this demand. A calf at 120 days weighing 150 kg could 

consume around 15 kg of milk. It is highly unlikely a cow would produce that much milk at 

that stage and so the calf gets its extra nutrients by consuming pasture. 

To achieve high calf weaning weights, cows must be well fed before and after calving. A 

high level of feeding after calving is also necessary for a high conception rate at rebreeding. 

Experience suggests that a feed budget should allow for a cow to eat in excess of 12 kg 

DM/day from the day of calving. How this will be achieved depends on the date of calving, 

and may require feed saved from late winter. Cows will often buffer their calves against 

underfeeding in early lactation by losing liveweight to maintain calf growth. However, this 

can not happen in poor conditioned cows (CS 2 (4) or less), so it is therefore desirable to 

have cows in a condition score of 2.5 (5) or better at calving. A recent trial at Massey 

University indicated that for heifers, a sward (pasture) height of 6 cm is sufficient in the first 

month after calving increasing to 10-12 cm during the second month. 

Date of weaning should depend on feed supply (it often depends on labour availability and 

sale date). If there is ample feed, there is little to be gained from early weaning unless there 

is an opportunity to use the cows in a mob for pasture control or preparation for other 

classes of stock. However, if hill country pastures dry out badly in summer, calves could be 

weaned and put onto what fresh pasture is available and the cows fed hard rations to 

relieve grazing competition. 


2.3 Optimum cow liveweight and cow efficiency 

18 

The best cow for hill country is a medium sized cow that weans a high proportion of its 

liveweight in calf weaning weight. The cow needs to be in good condition at weaning so 

she can then use her excess body condition as “supplementary feed” over the winter 

months. In fact, cows should be at their maximum liveweight and condition at weaning 

indicating they have eaten as much as possible of the excess spring-summer feed that 

usually occurs on hill country properties. 

It is possible for cows to wean calves (at 180 days age) that weigh 50% to 60% of the cow’s 

weight (compared to 35% to 45% on average). This is neither a new objective nor is it easy 

to achieve. In a project at Whatawhata Research Centre (Smeaton and others 2000) the 

optimum liveweight of mixed-age Hereford x Friesian cows was estimated to be 430 to 

450 kg (Figure 2.1). Anecdotally, many farmers run their cows at weights significantly 

heavier than this, thereby foregoing productivity advantages and running some risk of 

surplus fat in the udder which can jeopardise milk production (especially in heifers). At 

optimum weights in the Whatawhata project, cows rearing a live calf weaned calves at 180 

days of age that were 52% of their mother’s liveweight at mating. Including losses due to 

empty cows and calving losses, the ratio dropped to 44%. In summary cow productivity is 

extremely sensitive to: 

Cow liveweight relative to calf weaning weight 

Pregnancy rate 

Cow survival 

Calf survival, mostly around the calving period 

Figure 2.1: Illustration of optimum liveweight for Hereford x Friesian breeding cows 

Source: Reworked data from Smeaton and others (2000). 


2.4 Genetic selection for cow efficiency 

(other breeding traits are discussed in Chapter 6) 

19 

Traditionally, beef producers improve their herds by selecting for growth. Growth is an easy 

and economical trait to measure and is moderately heritable. Selection for growth traits has 

resulted in faster growing cattle, however it has also resulted in the introduction of some 

correlated undesirable traits such as increased birth weights leading to calving difficulties, 

delayed sexual maturity and increased herd maintenance requirements associated with the 

feed costs of larger animals. 

In most beef cattle production systems, researchers have established that 65% to 85% of 

total feed intake is required by the breeding cow herd, and that half of the total feed intake is 

required just to maintain cow liveweight. The costs of maintaining the breeding cow herd is 

clearly an important factor determining the efficiency of beef production. 

Despite its economic importance, farmers in New Zealand do not usually assess the cost of 

feed for their farming operation. The complementary roles of beef cattle on sheep farms 

complicate the economic assessment of feed efficiency in New Zealand’s mixed livestock 

farming systems as discussed elsewhere. However, as profitability is a function of both 

inputs and outputs, there is a need to consider avenues for reducing inputs in order to 

improve efficiency of production and increase profits. 

By selecting to improve the efficiency of feed conversion in a herd, the producer can strive 

to improve the efficiency of converting feed to gain, rather than concentrating on growth 

alone. Different measures of the efficiency of growth have evolved over the years because 

of the complex nature of feed use in the animal. The most commonly used definitions to 

describe the efficiency of growth are: 

Feed Conversion Ratio (FCR) 

This is a measure of the amount of feed eaten per unit of bodyweight or carcass weight 

gain. Since feed is the numerator, FCR should be minimised. Common values for growing 

ruminants grazing pasture are around 7-10 (kg fed consumed / kg liveweight gain) whereas 

pigs and poultry aim for values less than 2. The term Feed Conversion Efficiency (FCE) is 

also often used but the more correct term is FCR as it is a ratio (i.e. feed eaten per unit of 

gain) 


Efficiency of Feed Utilisation 

20 

Efficiency of feed utilisation is simply the reciprocal of FCR. The important point to 

remember is that more efficient cattle will have a lower FCR and a higher efficiency of feed 

utilisation. When comparing efficiencies from different studies or farms, calculations need 

to clearly state the measures (units) of inputs and outputs used. 

Residual Feed Intake 

An issue that is of considerable practical interest is the extent to which individual animals 

are more or less efficient than would be expected. Animals can be compared using net 

feed conversion efficiency or the residual feed intake. More efficient cattle can 

theoretically be found within any desired cattle weight range, and selection will not 

necessarily increase mature size. 

Net feed efficiency (NFE) refers to variation in feed intake between animals beyond that 

related to differences in growth and liveweight. Consequently it is expected that selection 

for improved NFE may reduce herd feed costs with little or no adverse changes in growth 

performance. Ranking animals on NFE requires measuring differences in their feed intake, 

liveweight and growth rate over a defined test period. A high NFE bull will consume less 

feed than expected over the test period and have a lower (negative) net feed intake. A low 

NFE bull will consume more feed than expected over the test period and have a higher 

(positive) net feed intake. An animal’s expected feed intake is predicted from the test 

groups’ average feed requirements for a particular growth (say 1 kg/head/day) and 

liveweight (say 300 kg). An animal’s net feed intake is simply the difference between its 

predicted feed intake and its actual feed intake. 

Selecting for efficient cows within a herd (usually when the first calf is weaned) 

Calf weaning weight, adjusted for calf sex, calf sire breed and year-of-birth of dam, has a 

moderate repeatability as a dam trait 1 of 0.37 (if adjusted for date of birth of calf), or 0.29 (if 

unadjusted for date of birth). Both of these traits, again as dam traits, are heritable, and the 

New Zealand heritability estimates were 0.26 and 0.19, respectively (Morris and others 

1993). Cow weights, adjusted for age, or year of birth, are highly repeatable (0.54), and 

moderately heritable (0.26). 

1 Trait: A measured genetic feature or characteristic 


21 

Selecting cows for a productivity objective is probably best achieved by using a linear index 

of calf weight and cow weight (e.g. A x calf weight difference from the adjusted mean, minus 

B x cow weight difference from the adjusted mean), rather than by using a ratio of the two 

adjusted weights. It is acknowledged that tagging and some recording is required, to get 

the best out of this procedure (i.e. calf-to-dam links, calf sex, date of birth), and if done on a 

commercial property, comparisons would need to be done within cow breeds or breed 

crosses, because of differing amounts of hybrid vigour expected. Managing separate 

grazing groups around or after calving may also complicate interpretation of the results. 

It is also important to remember that the sire contributes to herd productivity, i.e. the sire of 

the calf and also the sire of the cow. The Breeding Values of candidate sires need to be 

taken into account when purchasing service sires and when breeding/purchasing heifer 

replacements. The above process is rather complex, but the gains are there if farmers are 

willing to invest the time and the recording costs. 

2.5 Other pathways to cow efficiency 

Various efforts have been made to improve cow productivity either via twinning or by using 

embryo transfer to put high growth rate calf genetics into small, high milk producing cows, 

but commercial success remains elusive because the technology required remains 

immature or inadequate at several stages of the production cycle (see Chapter 4 also). 

Therefore, the right system at present would aim to: run cows at optimum weights; take 

maximum advantage of their ability to gain and lose weight to support milk production; use 

cows to maintain pasture quality; achieve high pregnancy rates and survival; and take 

maximum advantage of genetic opportunities and hybrid vigour. 

2.6 Cow liveweight and pasture damage 

Heavy cows are more likely to cause pasture damage and pugging on wet or steep hill 

country than light animals. In wet weather on steep hill country, damage can be severe, 

increasing the risk of erosion and weed invasion although this problem is manageable with 

care. This is not discussed in detail here (see Further Reading for more information). 


2.7 Weaning date, calf age at weaning 

22 

The main advantage of early weaning appears to be in retaining cow body condition. If the 

previous management has been correct, this should not be an important issue. However in 

case of droughts, and a requirement to graze cows off the farm as part of the drought 

management strategy, early weaning can be practiced. 

Weaning time is often determined by managerial convenience and timing of weaner sale 

dates in the district. Farmers often like to wean on the day of these sales so calves are 

trucked to the sale straight off their mothers looking in their best condition. However, if 

calves are not being sold at weaning, then weaning date can be related to feed supplies. In 

one recent study (Figure 2.2), calves weaned late (9 months of age) had a significant live 

weight advantage (55 kg) over calves that were weaned at the normal time (6 months of 

age). Most of this advantage was retained through to 18 months of age. This advantage in 

weight gain was shown to be due to milk intake. This study also demonstrated that weaned 

calves are more susceptible to internal parasites than calves that are still receiving milk. 

Figure 2.2: Mean calf liveweights for calves weaned at normal time (20 March), late 

weaned (26 June), or late weaned with no suckling from 20 March on. 

Source: Boom and others (2003). 


2.8 Further reading 

Boom, C.J.; Sheath, G.W.; Vlassoff, A. 2003. Interaction of gastro-intestinal nematodes 

and calf weaning management on beef cattle growth. Proceedings of the 

New Zealand Society of Animal Production 63: 61-65. 

23 

Thorrold, B. 2008. Management to minimise environmental damage, Ch 10 In Profitable 

beef production, A guide to beef production in New Zealand. A book, Ed 

D.C. Smeaton. Published by Meat & Wool New Zealand, Beef Council. Third 

Edition. Meat & Wool New Zealand, PO Box 121, Wellington. 

Smeaton, D.C.; Bown, M.D.; Clayton, J.B. 2000. Optimum liveweight, feed intake, 

reproduction, and calf output in beef cows on North Island hill country, 

New Zealand. New Zealand Journal of Agricultural Research. 43: 71 - 82. 

Smeaton, D.C.; Harris, B.L.; Xu, Z.Z.; Vivanco, W.H. 2003. Factors affecting commercial 

application of embryo technologies in New Zealand: a modelling approach. 

Theriogenology. 59: 617-634. 


Summary 

Profitable Farming of Beef Cows Chapter 3: Feeding beef cattle 

24 

Chapter 3: Feeding beef cattle 

This chapter describes the feed and grazing management requirements of breeding cows. 

Beef cattle should be fed at levels appropriate to their production target and the long term 

sustainability of the farming enterprise. Due to the variability of pasture growth and the 

demands of other livestock classes, it is rare for a farmer to get feed allocation absolutely 

correct. In calculating feed requirements for cattle, the requirement for maintenance, 

liveweight gain, milk production, and pregnancy are estimated separately and then added 

together. Requirements for cattle, based on these metabolic processes are provided. In 

practice many people calculate metabolisable energy (ME) feed requirements from feed 

tables or unwittingly by using farm management models that calculate intake as part of 

modelling their farm systems. 

The feed management strategy for a beef cow-breeding herd is determined by a balance of 

feed supply patterns, competing resources and market requirements. There are major 

benefits from running beef cows on hill country farms because of their flexible feed demand 

which can be aligned with the seasonal pasture growth curve. An additional benefit is their 

ability to assist in the management of pasture quality. An important attribute of the hill 

country beef cow is her ability to transfer feed from the late spring/summer period to winter 

via stored body fat. If this is managed successfully, it is often unnecessary to feed 

supplements to cows. 

For simplicity the annual nutritional requirements of spring calving beef cows are divided 

into the following periods: Post-weaning; Pre-calving; Post-calving; Post-mating. Both 

liveweight and body condition scoring are useful aids to checking the feeding and 

management of the herd at critical periods of the yearly production cycle. Condition 

scoring, seemingly less precise than weighing, is a practical way of monitoring the animals. 

The main management decision that affects the matching of the cow’s needs to pasture 

production is the time of calving. Since most of New Zealand’s beef cows are run on farms 

where sheep contribute the majority of stock numbers, the time of calving will also be 

influenced by the needs of other stock classes, usually lambing ewes.

3.1 Introduction 


25 

Beef cattle should be fed at levels appropriate to their production target and the long term 

sustainability of the farming enterprise. Due to the variability of pasture growth and the 

demands of other livestock classes, it is rare for a farmer to get feed allocation absolutely 

correct. Pasture growth rate predictions can differ from actual because of variable climatic 

conditions. Forage crops other than pasture are not used widely, but supplementary feed of 

various types (hay, silage, concentrates) may be used in times of feed shortage during 

winter or dry summers. 

The management on sheep and beef cattle farms ranges across the spectrum from 

extensive, where conservative stocking rates are used and the animal’s body weight acts as 

the main buffer between pasture production and feed requirements, through to intensively 

managed and planned systems where the farmer makes decisions on a daily basis to 

achieve this balance. In the more intensive systems, management to increase animal 

production is focused on lambing and calving liveweight targets, weaning date, flushing, and 

the timing of the sale of store lambs, weaners, cull ewes, cull cows and finishing steers or 

bulls. 

The points made above highlight the fact that most beef production is in conjunction with 

other livestock classes. When evaluating a beef cattle operation consideration must always 

be given to what other stock classes the cattle are complementing or competing against at 

various times of the year, and how their performance will change if the beef system is 

changed. 

3.2 Energy requirements of cattle 

Feed requirements represent the amount of feed which must be consumed in order to 

sustain a defined level of production. For any specified level of performance 

(e.g. pregnancy, liveweight gain or milk production), sufficient nutrients and energy must be 

supplied to the animal tissues to meet metabolic demands. Requirements can be 

conveniently expressed as metabolisable energy (ME) because with most pastures, energy 

is the most limiting factor for a given level of production. Other nutrients such as protein, 

minerals and vitamins (except where there is a known deficiency) are almost always 

present in adequate amounts. However, in some instances e.g. young growing animals, 

protein may be limiting, especially on low digestible mature type pastures.

The major determinants of the energy requirement of grazing livestock are: 

liveweight and body condition 

stage of pregnancy 

level of milk production 

rate of liveweight gain or loss 

composition of liveweight gain or loss 


26 

level of activity in eating and movement 

possible effects of climate 

sex of animal 

walking distance and climbing hills 

Obviously it is difficult to include all these variables in tables of ME requirements that are 

easy to use. In calculating feed requirements for cattle, the requirements for maintenance, 

liveweight gain, milk production, and pregnancy are estimated separately and then added 

together. The energy requirements of growing cattle are not covered here. Refer instead to 

the Further Reading section (Nicol and Brookes, 2007; Smeaton 2007). 

3.2.1 Requirements for maintenance 

The ME requirement for maintenance is the amount of ME that must be supplied to provide 

energy needed for essential body functions. If this energy is not supplied in the diet it must 

be obtained by mobilising body tissue, predominantly fat. 

As liveweight increases, so too does maintenance energy requirement (Table 3.1), with 

every 100kg increase in liveweight requiring an additional 11 MJ ME/day. Increased 

grazing and activity costs on hard hill country are significant. These maintenance 

requirements are significantly higher than those used by Geenty and Rattray (1987).


27 

Table 3.1: The metabolisable energy requirement (MJ ME/cow/day) for maintenance of 

beef cows. Source: Nicol and Brookes (2007). 

Notes: 

Liveweight (kg) 

Land class 300 400 500 600 

Easy hill - 55 66 77 

Hard hill 50 65 75 - 

Add/subtract 7% per MJ ME for diets below/above 10.5 MJ ME/kg DM. 

Add 15% for adult bulls. 

A guideline requirement for maintenance can be given as: 

0.62 MJ ME/kg liveweight 0.75 for cows on easy hill country 

0.70 MJ ME/kg liveweight 0.75 for cows on hard hill country 

3.2.2 Requirements for pregnancy 

The amount of energy used for both maintenance and growth of the foetus and the products 

of conception depends on: 

Days from conception. The greatest increase in requirements occur in the last third 

of pregnancy 

Number of offspring (twins rarely exceed 1% of births in beef cattle) 

Size of the foetus 

Guideline requirements for pregnancy for calves of varying birthweights are shown in 

Table 3.2. These values are additional to the maintenance requirements of the cow.


28 

Table 3.2: The metabolisable energy requirement of beef cows (MJ ME/cow/day) for 

pregnancy (in addition to maintenance requirement). Source: Nicol and Brookes (2007). 

Notes: 

Calf 

birth weight (kg) 

Weeks before 

calving 

-12 -8 -4 0 

Total for 

Pregnancy 

MJ ME/cow/day MJ ME 

30 6 11 20 34 1700 

40 9 15 26 45 2300 

50 11 18 32 55 2800 

Add these to the maintenance requirement of the cow. 

Adjust proportionately for pregnancy rate of the herd, for example, 

Pregnancy rate = 95%, ME for 40 kg birthweight, 4 weeks pre-calving 

= 0.95 x 26 = 25 MJ ME/cow/day. 

3.2.3 Requirements for lactation and calf growth 

The ME requirement for milk production depends on: 

Total milk yield (litres) 

Milk composition - because milk varies in concentration of fat, protein and lactose, 

the ME requirement per litre will also vary. 

It is extremely difficult to know the milk production of beef cows but it will usually range from 

5-10 litres/day for single suckled cows. In addition and as a guideline, 5.8 MJ ME/kg milk is 

assumed. 

The costs of lactation and calf growth (Table 3.3) are estimated as 60 MJ ME/kg calf 

weaning weight (slightly less for very light calves). Assumptions have been made about the 

proportion of the requirements of the calf which has been supplied by milk and grazing. 

However, this ratio does not markedly affect the total ME requirements for calf growth to 

weaning.


29 

Table 3.3: The metabolisable energy requirements of beef cows and their calves during 

lactation (in addition to cow maintenance requirements). Source: Nicol and Brookes (2007). 

Calf weaning 

weight (kg) 

Months after calving Total for 

lactation 

+1 +3 +5 +7 

MJ ME/cow + calf/day MJ ME 

150 35 45 55 55 8700 

200 40 55 65 75 12000 

250 50 70 85 95 15000 

300 60 80 100 115 18000 

Notes: 

Add these figures to cow maintenance requirement. (See Table 3.1) 

Adjust proportionately for weaning %, for example 

85% weaning, 200 kg calves, 5 months = 0.85 x 65 = 55 MJ ME/cow/day. 

Add/subtract 8% MJ ME for diets below/above 11.0 MJ ME/kg DM. 

3.2.4 Liveweight loss or gain 

When animals lose weight, mobilisation of body tissue releases energy which therefore 

does not have to be supplied by the diet. In lactating animals, this energy can be used to 

maintain milk yield, even though the animal is losing weight. The figure often used for 

New Zealand beef cows is 55 MJ ME required per kg of LWG gain, and 1 kg of liveweight 

loss in mature cows substitutes for around 30 MJ ME of herbage intake. Thus the net cost 

of losing and gaining a kg of liveweight is 25 MJ ME/kg of liveweight. 

Condition Score (CS) and liveweight change 

Target condition scores are often given for particular stages of the production cycle. When 

using the 0 to 5 CS scale, one unit change in CS is equivalent to 75 kg for a 500 kg 

Hereford cow. On the 1 to 10 scale, the weight change per unit is about 40 kg 

The approximate quantities of ME per 1 unit change of condition score (Scale 0-5) range 

from 4815 MJ ME/CS for a non lactating cow of with a CS of 2.0, to 5650 for a non lactating 

with a CS of 4. For lactating cows it is 3450 (CS 2.0) and 4500 (CS 5.0) MJ ME/CS 

change. These values would be about half for the 1 to 10 scale. Condition scoring is 

discussed in more detail later in this chapter.

3.3 Calculating feed requirements 


30 

In practice most people calculate ME feed requirements in computer models without even 

realising it. Less commonly, they may estimate them from feed tables such as in Table 3.1 

to 3.4. Requirements in kg DM/head/day can be determined from these tables once a value 

of the energy (ME) content of feed is known. Pasture typically contains 8 to 12 MJ ME/kg of 

DM depending on the quality of pasture. Note that some feed tables are quoted in kg DM. 

These should be used with caution when using them for pastures of varying energy content. 

Table 3.4 provides an example of how the previous information can be used to compute the 

annual metabolisable energy requirements for breeding cows with different levels of 

productivity on either good or hard hill country. Note the greater (23%) feed requirements of 

the more productive cow in the better environment compared to that of the cow in the hard 

hill country. 

Table 3.4: The annual ME requirements of beef cows in hard and easy hill country. 

Source: Nicol and Brookes (2007). 

Specifications Hard hill Easy hill 

Liveweight (kg) 400 550 

Weight loss/gain (kg total) 30 30 

Calves born/cow joined 92 97 

Calf birth weight (kg) 30 40 

Calves weaned/cow joined 86 90 

Calf weaning weight (kg) 

ME requirements (MJ ME) 

175 250 

Maintenance 365 x 65 = 23725 365 x 72 = 26280 

Weight loss/gain 30 x 25 = 750 30 x 25 = 750 

Pregnancy 0.92 x 1700 = 1565 0.97 x 2300 = 2230 

Lactation and calf growth 0.86 x 10350 = 8900 0.90 x 15000 = 13500 

Total annual (MJ ME/year) 

Notes: 

35000 42750 

Maintenance requirement from Table 3.1 

Net cost of loss and regain of weight is 25 MJ ME/kg (Para 3.2.4). 

Total requirement for pregnancy from Table 3.2 and number of calves born (NCB). 

Total requirement for lactation and calf growth from Table 3.3 and number of calves weaned

3.4 Management and nutrition of the beef cow 

3.4.1 General comments 


31 

The management strategy for a beef cow-breeding herd is determined by a balance of feed 

supply patterns, competing resources and market requirements. There are major benefits 

from running beef cows on hill country farms because of their flexible feed demand which 

can be aligned with the seasonal pasture growth curve. An additional benefit is their ability 

to assist in the management of pasture quality. In this respect, they play an important role 

on kikuyu pasture in Northland and brown-top dominant swards elsewhere. Hill country 

farmers marketing weaners in the autumn will often put in place a strategy to cope with 

calving ahead of the spring pasture growth, in order to supply the market with older, and 

therefore larger, weaners. Farmers marketing progeny in the following spring or autumn, or 

finishing the weaner steers themselves, have the flexibility of being able to calve at a more 

appropriate time in relation to their pasture growth curve. An appreciation of the pasture 

growth curve of a farm is fundamental to the management of any pasture based production 

system. When calving before the spring pasture growth flush, the cow is placed in a more 

competitive rather than a complementary position with other livestock classes that might 

also be able to utilise that same scarce feed. 

For simplicity we can divide the annual nutritional requirements of mature spring calving 

cows into the following periods: Post-weaning; Pre-calving; Post-calving; Post-mating. Both 

liveweight and body condition scoring are useful aids to checking the feeding and 

management of the herd at critical periods of the yearly production cycle. Condition 

scoring, while seemingly less precise than weighing, is nevertheless a practical way of 

monitoring the animals. 

3.4.2 Post-weaning (weaning through to 4-6 weeks pre-calving) 

Weaning of beef calves normally occurs at 5 to 7 months of age. It can be carried out 

successfully at 4 months (this can be an appropriate drought management strategy) 

provided appropriate provision is made for post-weaning feed for the calf. In the beef cow 

calendar this leaves 5 months of the year that beef cows are low priority stock and can 

function as 'work horses' eating rank pasture and controlling shrub re-growth provided they 

were in good condition at weaning . During this time, priority can be given to other classes 

of livestock and cows become one of the few groups available that can be restricted in the 

interests of pasture development and utilisation. This is a major justification for maintaining


32 

a breeding cow herd on hill country. Not only has it significant advantages for the farm as a 

whole, but it has in fact been shown to be beneficial for the cows to lose around 10% of 

their liveweight in the post-weaning period. 

Cows losing that order of liveweight have increased longevity and suffer no reduction in 

performance; provided their nutritional requirements are met in the pre- and post-calving 

periods and lost liveweight is regained. Cows fatter than condition score (CS) 3.5 (7 on 1 to 

10 scale) at calving are more prone to calving difficulties and to metabolic disease. A 

reduction in intake around calving should not be carried out too rapidly with fat cows, as 

they can suffer from hypomagnesaemia if subjected to sudden severe restrictions in intake. 

Some farmers rotationally graze their cows behind the ewes in a winter rotation during this 

period. In such situations cow intakes are very low e.g. Angus cows can eat as little as 

3-3.5kg DM/day. This highlights their efficiency and supports the theory that an efficiently 

managed beef cow could have a true winter stock unit cost of 3.5 stock units compared to 

the commonly accepted value of 6 to 7. Minimising cow feed requirements during 

maintenance periods can have a significant impact on overall feed efficiency and therefore 

profitability on a hill country sheep and cattle farm. This should be a consideration when 

establishing appropriate stock unit equivalents. 

3.4.3 Pre-calving (from 4-6 weeks pre-calving to calving) 

Cows that have lost in the order of 10% body weight post weaning need to regain some 

condition pre-calving and will need to be on a rising plane of nutrition up to and through 

mating. If they do not, there is a risk they will be too weak at calving and prone to metabolic 

problems, and calf losses can be high (of the order of 10%-20%). 

A relatively short period (4 weeks) of high nutrition (6-8kg DM intake/cow/day) is usually 

sufficient. Note that the calf is gaining at 250 grams/day in utero during the last month of 

pregnancy. If feed is available, liveweight gain on cows will be easier to achieve pre-calving 

than during early lactation and is unlikely to have any significant effect on calf birth weights, 

except at extremes of feeding levels. If cows calve at CS 2.5-3.0 (5 to 6) it will make the 

mating condition target of 3.0 (6) a lot easier to meet.


33 

While poor pre-calving nutrition and body condition score can exacerbate post-calving 

under-nutrition problems, priority in terms of feed allocation should be given to the 

post-calving period. This can be achieved by shedding cows out from a moderate plane of 

nutrition to a high plane as they calve, by strip grazing, shifting into saved feed at the start 

of calving or calving onto spring growth. Some farmers, by calving late enough are able to 

set stock cows amongst ewes and lambs at calving. Whatever system is used to apportion 

feed, CS at calving is critical because it affects CS at mating, one of the most critical points 

in cow management. 

3.4.4 Calving to mating 

Research suggests that Angus and Friesian cross beef cows need to eat in excess of 12 kg 

DM /day from the day of calving through to mating. Larger breeds will require 

proportionately more. How this feed demand is met will depend on the time of calving, but 

even herds calving close to their pasture growth curve will need some feed carried forward 

from late winter. The area chosen for calving should be of easy contour and free of hazards 

like creeks, tomos (underground holes) and swamps as these cause significant calf losses. 

Post-calving nutrition is critical for several reasons: 

Cow survival - the majority of cow deaths from hypomagnesaemia occur 

post-calving and peak in the second week of lactation as the milk demands of the 

calf increase. Provision of high quality pasture above 2500kg DM/ha (12 cm high) 

is the key to its prevention. In some conditions, magnesium supplementation may 

be required for a period during and after calving. Other metabolic conditions that 

can occur at this time of the year are milk fever and ketosis. However they play a 

very minor role in beef cow losses and are also prevented by correct cow condition 

at calving and post-calving nutrition. 

Calf growth rates - cows under-fed in early lactation will buffer their calves by 

losing liveweight to maintain milk production. However, with high milk producing 

Hereford x Friesian cows at a CS of 2.5 (5) or better at calving, it may be 

necessary to restrict feed for the first 3-4 weeks post-calving. This is because the 

calves are unable to consume all the milk produced by these high producing cows. 

A recent trial indicates that a pasture sward height of 6 cm is sufficient for 

beef x dairy heifers during the first month of lactation, increasing to 10-12 cm 

during the second month of lactation.


34 

Calves should gain at least 1.0kg/hd/day while suckling their dams. Milk makes up 

a large proportion of their diet up to 12 weeks of age after which they can consume 

up to 50% of total diet as grass. 

Subsequent cow pregnancy rate and calving pattern – There are two aspects to 

consider: 

1. Whether the cow is pregnant or not 

2. When the pregnancy was achieved 

Cows fed in excess of 12kg DM/day from calving until prior to mating should be near a 

condition score of 3 (6+) at mating. In this condition they will have high conception rates 

(>95%) over a breeding interval of 63 days or 9 weeks assuming bulls are fertile. 

Under-nutrition in the period from calving to mating can depress pregnancy rates. There 

have been numerous trials to illustrate this, e.g. Table 3.5. 

Table 3.5: Effect of post-calving pasture allowance on cow pregnancy rate (Nicoll, 

1979) 

Post Calving 

Nutrition 

Allowance 

kg DM/day/cow 

Pregnancy 

Rate 

High 20 100% 

Low 8 78% 

This depression in pregnancy rate is produced as a result of lengthening of the post partum 

anoestrus period and a reduction in conception rates. A cow has only 85 days to get 

pregnant to calve on a 365 day schedule. Post-partum anoestrus periods longer than this, 

and/or low conception rates leaving the cow empty at 85 days, will result in a later calving 

next year. If these factors leave the cow empty after around 120 days then she will 

generally be unable to get in calf because of bull withdrawal.

3.4.5 Mating - weaning 


35 

If a 63 day breeding interval is used for mature cows, then calves will be aged between 

80 to 140 days at bull withdrawal. Weaning can be carried out at this stage but very high 

quality feed is required to achieve calf liveweight gains of the same order as later-weaned 

calves (e.g. at six months). Cows with a condition score of 3 (6) or better at mating can be 

used in the late summer-autumn period to clean up low quality summer pasture with their 

calves at foot. They will lose some body weight (20kg) while ensuring milk production is 

maintained for their calves but if weight loss is too severe some minor effects in calf 

weaning weights can result. Care is obviously required as calves are also competing at this 

time for available pasture. Age at weaning obviously has an impact on calf weaning weight. 

There are reasons for weaning both early and late, depending on weather and feed supplies 

(Chapter 2). 

3.5 Matching nutritional requirements to the seasonal pasture supply 

pattern 

The main management decision that affects the matching of the cow’s needs to pasture 

production is the time of calving. Since most of New Zealand’s beef cows are run on farms 

where sheep contribute the majority of stock numbers then the time of calving will also be 

influenced by the needs of other stock classes, usually lambing ewes. As always, it is 

important that the cow complements other livestock classes rather than competing with 

them. 

In Figure 3.1, a stylised cow feed requirement graph is shown with an example pasture 

growth curve to demonstrate the effects of different calving dates on the match between 

feed supply and animal demand. A mid October to late November calving span best suits in 

this example. 

Once timing of calving has been decided upon, there are advantages in managing the entire 

herd to calve as quickly as possible during that period, rather than extending calving over 

many months. Most farmers who farm beef cows restrict mating to 9 weeks or less. They 

should aim to get as many of the cows pregnant as possible during the first 3 weeks of 

mating to enable more controlled management. If all cows are at the same stage of 

pregnancy/lactation feed budgeting will be easier.


36 

Figure 3.1: Matching beef cow nutritional requirements to Taihape hill country pasture 

growth. The pasture growth curve is the average of 3 years of data. 

Source: Hughes and Morris (1998). 

3.6 Supplementary feeding of beef cows 

The transfer of surplus pasture in spring/summer through to winter via the seasonal cycle of 

body weight change in the mature beef cow is a key component to her successful 

integration into hill country management systems. However, if supplements are to be used, 

conserved pasture (hay, silage or autumn/winter annual feed) or nitrogen fertiliser are the 

most common due to cost. In some cases winter crops may be grown (green feed oats) but 

these are more likely to be used for growing cattle. The main purpose for feeding 

supplements in beef cow herds is to overcome winter or summer deficits. Supplements can 

supply 20-80% feed intake during these seasons and in some cases may be the sole feed 

in the cow’s diet. Supplementary feed does not need to be fed in some districts, such as 

the Waikato or Northland, as pasture feed supplies can be matched with cow demand.


37 

Silage is more nutritious and easier to make than hay but has the disadvantage of requiring 

machinery for feeding out unless fed via a self-feeding system (see below). Silage can be 

made under a wider range of weather conditions and has the big advantage that it is often 

cheaper to make than hay, especially if stored as a stack. Hay can be a viable alternative 

when equipment is not available and only small amounts are fed to animals. It can also be 

easily transported and hence brought in to a hill country property with little flat land. 

Some farmers use self feeding systems to feed silage. A common practice is to set up a 

barrier or platform which could simply be an electric wire placed up against the silage stack 

and moved forward each day. Cows can be maintained on 100% silage through to the last 

2 to 3 weeks of pregnancy, or they can have a percentage of their diet as silage and have a 

run back into an area of grass each day. Cows can easily eat 7-8 kg DM of silage per day. 

It is difficult in most hill country environments to have enough stock to cope with the very 

rapid rate of pasture growth in the late spring. The options of taking areas out of grazing for 

hay, silage or winter crops are not appropriate for hill country. Beef cows are very useful to 

"mop up" a proportion of this spring pasture growth flush. When pasture reaches a height of 

8 cm or more, beef cattle are capable of eating much more than they need for their own 

maintenance and milk production and can readily gain liveweight at 1.0 kg/day. In this way 

cows play an important role in transferring feed from the late spring/summer to winter via 

stored body fat. 

The pasture required for 1.0 kg liveweight gain per day for 150 cows for 30 days is around 

30 tonnes of dry matter. This is the equivalent of 1300 conventional hay bales. So the 

statement that "the beef cow is a self-propelled hill country hay baler that uses no string" is 

well founded. This surplus feed is stored as liveweight (mainly fat) at very little extra cost as 

it takes relatively little extra energy to maintain a heavy fat cow than a light thin one. 

Every 10 kg of extra liveweight that a beef cow takes into the autumn/winter represents a 

saving of 8% of her feed requirements over the 100 day winter period. As she loses body 

weight, she effectively feeds herself. In addition there are no non-biodegradable residues of 

plastic bale covers left or fossil fuel used in feeding out. 

If required, a wide variety of supplements are available and Appendix 1 lists the nutrient 

composition of a variety of feeds that could be fed to cattle. Dry matter %, energy content 

(MJ ME/kg DM), crude protein and mineral concentrations are given. Note the varying


38 

energy content of good versus poor quality hay and silage. In many instances, it is not 

economic to feed the supplements listed. 

3.7 Assessing the adequacy of feeding 

There are several methods by which to assess the success or otherwise of a feeding 

regime. Weighing cattle and calculating average daily liveweight gains per head between 

two weighing dates is the most obvious method used. There are problems sometimes in 

interpreting the result as gut fill can result in an over estimate of liveweight by up to 7%. 

This source of variation is minimised by weighing cattle at the same time of day at each 

weighing and being careful about standardising weighing at either the start or end of the 

grazing of a paddock. It is not necessary to weigh every animal and farmers will often weigh 

an indicator mob to assess how feeding is going. Frequent weighing is onerous but does 

mean a rapid response to any problems is possible. Alternatively, animals can be weighed 

occasionally and their liveweights compared against target values. 

Assessment of residual pasture mass will also give an indication of how livestock are 

performing and is easier (especially if done by eye appraisal). If animals are grazing 

pastures out to less than 1000/kg/ha then the chances are they will be growing at around 

0.2–0.5 kg/day, whereas if they leave 2000 kg/ha they are likely to growing in excess of 

1.0 kg/day. This depends on the season and on the pre-grazing herbage mass and quality 

and is dealt with in more detail elsewhere. (See Further Reading at the end of this chapter). 

In the beef cow herd there are some indictors that can point to longer term problems with 

feeding. These include calving and weaning percentages, length of the calving period, 

range in size and age of calves at weaning, and low in-calf rates. Low weaning 

percentages, a long calving period and a wide range of calf sizes at weaning could all be 

indicators of poor nutrition. Mating and calving dates are also an indication of the closeness 

of the match of animal requirements with seasonal pasture growth. 

The key times likely to influence production and profitability are calving, mating and 

weaning. Assessment of cow liveweight at these times will provide information that is vital to 

for feed planning. An accurate assessment of cow body reserves can be an important aid 

towards optimising nutritional management and reproductive efficiency. Interpretation of 

liveweights can be difficult owing to differences in mature size of cattle, stage of pregnancy,


39 

and gut fill as described above. Hence, the introduction of a body condition scoring system 

which allows cow body reserves to be assessed without the need for weighing. 

3.8 Condition scoring 

Condition scoring (CS) provides a measure of the level of body reserves of a cow 

independent of liveweight, and is a more reliable description of cow condition than is 

liveweight alone. It can be used as an aid when making management decisions. The 

method involves assessing the level of fat cover on the rear half of the cow’s body 

(see Appendix 1). Two systems are in use. The 0 to 5 scale works in increments of 0.5 

(Table A1.1A), and is widely used in the Australian beef industry and the sheep industry in 

New Zealand (Lowman and others, 1976). The 1 to 10 system is the same as that used in 

the New Zealand dairy industry (Table A1.1B). Both systems have their merits and are both 

effective. Cows can be scored for body condition regularly, particularly in cases where 

weighing is not practical. The technique is easy to learn and does not require special 

equipment. Two research studies indicate that one unit change in CS in British breeds of 

cattle could be taken as equivalent to 50 kg (0-5 scale) liveweight. For Friesian, and large 

European breeds (Charolais, Simmental) it may be equivalent to 100 kg (Lowman et al. 

1976). On the 1 to 10 scale, one unit change is equivalent to 25 kg liveweight for smaller 

breeds and 40 to 50 kg liveweight for bigger breeds. 

There are five occasions when it may be beneficial to condition score beef cows. They are: 

Weaning time - this ensures young cows (heifers) are given priority if they are in 

poor condition 

30-45 days after weaning - to see how feeding is going and adjust accordingly 

60-90 days prior to calving - last opportunity to get things correct prior to calving 

Calving - separate the thin cows and priority feed these 

Mating - gives an indication of next year’s production levels 

Target liveweights and CS for various sized beef cows at the critical times of year, are given 

in Table 3.6 Note three different sized cows are given. These could represent different cow 

breeds on the same farm (e.g. Angus, Hereford x Friesian, or Hereford x Simmental) on 

different classes of country such as hard hill country where mature liveweights are poor 

through to easy well developed country where mature liveweights are good.

Table 3.6: Target seasonal liveweights and CS for various cow types 

Cow size Weaning Mid Winter Pre calving Mating 

Small 430 380 400 410 

Medium 470 420 440 450 

Large 550 500 520 530 


40 

Condition Score 

(0 to 5 scale) 

3 - 3.5 2.5* 2.5* 2.5 - 3.0 

Condition score 


6+ 5* 5* 5.5 

* These CS values are negotiable, provided the cow is fit and healthy, has good blood 

magnesium levels and can gain weight to reach the mating CS targets shown. 

In all instances in a well managed herd, cow liveweight is usually at its maximum in the 

autumn at or just prior to weaning. Liveweight should be within 5% of maximum at mating. 

Aim to manage breeding cows within the target ranges: 

If breeding cows are too fat at calving (high CS), they are prone to get milk fever, can have 

calving difficulties and may have reduced milk production. Most importantly, running beef 

cows at too high a CS wastes valuable feed reserves. 

Cows with a high CS at weaning can lose a lot of weight safely in autumn and winter, but 

excessive weight loss in late pregnancy may increase the risk of pregnancy toxaemia 

(ketosis) and grass tetany (staggers or hypo-magnesaemia). Returns to first oestrus will be 

delayed if cows fail to reach the target CS shown for mating and they will suffer reduced 

milk production and reduced calf growth rate.



41 

Geenty, K. G.; Rattray, P. V. 1987. The energy requirements of grazing sheep and cattle. 

In: Livestock Feeding on Pastures. New Zealand Society of Animal Production. 

Occasional Publication No 10: 39-54. 

Hughes, P. L.; Morris, S. T. 1998. Management solutions for beef cows. New Zealand 

Beef Council Southern Regional Field Day, Gore, 8 May 1998, Alexandra. 

Nicoll, G.B. 1979. Influence of pre- and post- calving pasture allowance on hill country beef 

cow and calf performance. New Zealand Journal of Agriculture Research 22: 

417 - 424. 

Morris, S.T. 2007. Pastures and supplements in beef production systems. Ch 14, In: 

Pasture and Supplements for grazing livestock. A book published by New Zealand 

Society of Animal Production, c/o Dairy NZ, Hamilton, New Zealand. Occasional 

Publication No. 14. 

Nicol, A.M.; Brookes, I.M. 2007. The metabolisable energy requirements of grazing 

livestock. Ch 10, In: Pasture and Supplements for grazing livestock. A book 

published by New Zealand Society of Animal Production, c/o Dairy NZ, Hamilton, 

New Zealand. Occasional Publication No. 14. 

Smeaton, D.C. 2007. Feed requirements of beef calves from age 6 months to slaughter, 

Ch 5, In: Profitable beef production, A guide to beef production in New Zealand. A 

book, published by Meat & Wool New Zealand, Beef Council, Third Edition. 

Meat & Wool New Zealand, PO Box 121, Wellington.

Summary 

42 

Chapter 4: Reproduction in the beef cow herd 

A major factor determining the productivity and profitability of beef cow herds is their 

reproductive performance. The efficiency of a beef cow enterprise depends on the cow's 

lifetime output (total liveweight of calves weaned/cow). Reproductive efficiency in cattle, as 

measured by the number of calves born and weaned each year per 100 females in the 

breeding herd, is considered the most important economic factor in cattle production. 

Reproduction has at least twice the impact of growth or carcass characteristics on 

profitability for cow-calf producers who sell their calves at weaning. A high lifetime output 

for a beef breeding cow depends on a high reproductive rate where the target is as close as 

possible to one calf per year per cow in the herd (100% calving). 

Useful definitions of reproductive efficiency that can be measured in beef cow herds are: 

Pregnancy rate - the number of cows pregnant per 100 cows joined with the bull. 

Calving rate - the number of cows calving per 100 cows joined with the bull. 

Calf survival - number of calves weaned per 100 calves born. 

Calf weaning rate - number of calves weaned per 100 cows joined with the bull 

Survey data indicate that the average calf weaning rate in New Zealand is static at 80 to 

84%. This is in spite of the fact that considerable variation exists in calf marking % 2 among 

herds, from year to year in the same herd. We can conclude from this data that there is 

considerable potential to improve reproductive efficiency in our beef cow herds but that it 

has proven to be very difficult to achieve change. 

Useful reproductive targets for an adult beef cow herd are: 

A 12 month (365 day) mean calving interval 

A 63 day (3 cycles) mating period for cows 

A pregnancy rate of at least 95% for adult cows 

A calf weaning rate of at least 90% in adult cows (some do better than this) 

Less than 3% abortion rate 

At least 60% of cows calving in the first 21 days of calving 

2 Calf marking %, recorded in mid-lactation is a commonly used proxy for calf weaning %. 

Profitable Farming of Beef Cows Chapter 4: Reproduction in the beef cow herd

Less than 5% incidence of calving difficulty (difficult birth) 

It is usually more profitable to first calve heifers at 2 rather than 3 years of age because: 

43 

Lifetime output is increased by about 10% 

Land use for heifer rearing is reduced by nearly 50% 

Rate of genetic gain is increased (especially for bull breeding herds). 

Information for selecting replacement heifers is available much earlier in a female’s 

life - this is especially so if more heifers than are required as replacements are 

mated 

This chapter discusses all aspects of beef cow reproductive management including factors 

affecting calving difficulty, bull performance, pregnancy detection and new reproductive 

technologies including twinning and cloning. 


A major factor determining the productivity and profitability of beef cow herds is their 

reproductive performance. The efficiency of a beef cow enterprise depends on the cow's 

lifetime output (total liveweight of calves weaned/cow). This is a complex trait affected by 

many factors (Figure 4.1). 

A live calf born and weaned to each breeding female each year is the primary objective for 

successful reproduction. However, cows are not managed as individuals but as a herd, so 

the economic evaluation of total herd reproductive performance is critical. Reproductive 

efficiency in cattle, as measured by the number of calves born and weaned each year per 

100 females in the breeding herd, is considered the most important economic factor in cattle 

production. Reproduction is at least twice as important as growth or carcass characteristics 

for cow-calf producers who sell their calves at weaning. 

A high lifetime output of a beef breeding cow depends on a high reproductive rate where the 

target is as close as possible to one calf per year per cow in the herd. The production cost 

of failing to rear a calf is high and is difficult to make up. For example a cow that rears 

7 calves each weighing 220 kg has a total lifetime output of 1540 kg of calf weaned. To 

produce the same total lifetime output in 5 calvings would require an annual calf weaning 

weight of 308 kg. 


Useful definitions of reproductive efficiency that can be measured in beef cow herds are: 

44 

Pregnancy rate - the number of cows pregnant per 100 cows joined with the bull 

Calving rate - the number of cows calving per 100 cows joined with the bull 

Calf survival - number of calves weaned per 100 calves born 

Calf weaning % (rate) - number of calves weaned per 100 cows joined with the bull 

Each of these reproductive indices are useful in determining the reproductive efficiency of a 

beef cow herd as they allow abortion rates, postnatal calf mortality rate and calf losses to 

weaning to be calculated. These indices or ratios have the limitation that they take no 

account of the duration of joining or the interval between calvings. Furthermore it takes no 

account of the fact that some females with the potential to produce calves are not given the 

opportunity (e.g. yearling heifers). The indicators also assume a natural mating system with 

bulls (probably 98% of beef cows are mated in this manner), taking no account of age and 

number of bulls used or the liveweight of cows in the herd all of which can contribute to 

overall herd reproductive efficiency. 

Figure 4.1: The major factors influencing weight of calf weaned per cow bred. 

Source: Taylor and Field (1999). 


4.2 Potential reproductive rate 

45 

The reproductive rate of beef herds has been documented by the Meat & Wool New 

Zealand Economic Service which records the number of calves marked per 100 cows joined 

with the bull (calf marking percentage). Note there are few calf deaths between calf 

marking (when calves are around 60-90 days of age) and calf weaning. The survey data 

indicate that the percentage of calves weaned is static at 80 to 84%. This is in spite of the 

fact that considerable variation exists in calf marking percentage among herds and there is 

often variation in pregnancy rate from year to year in the same herd. We can conclude from 

this data that there is considerable potential to improve reproductive efficiency in our beef 

cow herds but that it has proven to be very difficult to achieve change. 

In New Zealand where pasture production is seasonal, most beef cow farmers have a 

compact calving season, usually in spring. The biological timetable must be worked to a 

tight schedule if a 365 day calving interval is to be maintained because: 

Pregnancy (gestation length) is about 282 days (range 270 - 290). 

To maintain a calving interval of one calendar year there are only 83 "non pregnant" 

days available to the cow to get pregnant. 

An excessive calving spread reflects reduced efficiency and reduces the likelihood of cows 

getting pregnant. 

The advantages of a compact calving include: 

Easier allocation of feed and metabolic supplements to meet the cow’s feed 

requirements 

Easier allocation of calving paddocks 

Ease of supervision at calving 

An even line of weaners for sale 

An even line of replacement heifers 

A higher proportion of cows are likely to be cycling when the bull goes out 

Heavier average weaning weights. 


46 

It is relatively easy to place a monetary value on a condensed calving pattern compared to 

a longer period. Consider two herds: 

Herd A. – Assumptions; spread calving: 

105 day calving period 15 August to 30 November 

Equates to bulls out 1 November and in on 20 February (i.e. 5 cycles of mating) 

Calving spread as in Figure 4.3 

Calf birth weight of 35 kg 

Weaning 1 March i.e. 200 days from start of calving 

Average LWG birth to weaning = 1.0 kg/calf/day 

Calves in each 21 day spread are taken on average to be born at the mid-point 

Weaning weights calculated as: 

(1 st period average age = 190 days (mid way 180 - 200 days) 

liveweight = (190 x 1.0) + birthweight (=35 kg) = 225 kg 

Subsequent calf weights for each 21 day spread are: 

1 – 21 = 225 kg 

22 – 42 = 203 kg 

43 – 63 = 183 kg 

64 – 84 = 61 kg 

85 – 105 = 140 kg 

The average weaning weight for this cow herd is 187 kg. 

Herd B. – Assumptions; condensed calving: 

63 days calving period 15 August to 18 October 

Bulls out 20 November and in 20 January (3 cycles) 

Calving spread as in Figure 4.4. 

The average calf weaning weight for Herd B would be 215 kg (using the same assumptions 

as for Herd A). 

The advantage of Herd B over Herd A is 28 kg. If we value calf liveweight at $2.20/kg, the 

advantage to a calf from Herd B is $62 and for a 200 cow herd with a 90% weaning rate the 

advantage is over $11,090. 


Figure 4.3: Typical hill county calving spread (Herd A) 

Figure 4.4 Preferred calving spread for hill country herd (Herd B) 

47 

This calving pattern coincides with 

1 November - mid February mating 

Calving period: 8 August – 22 November 

This calving pattern coincides with a 

20 November - 20 January mating period 

Calving period: 29 August - 29 October 

In practice there is often a compromise between acceptable duration and timing of calving, 

and potential reproductive performance. It is the successful management of this 

compromise that is the key to successful reproduction in beef breeding cow herds. 


48 

We can now, however, identify some useful reproductive targets for an adult beef cow herd. 

12 month (365 day) mean calving interval 

A 63 day (3 cycles) mating period for cows 

A pregnancy rate of at least 95% for adult cows 

A calf weaning percentage of at least 90% in adult cows (some do better than this) 

Less than 3% abortion rate 

At least 60% of cows calving in the first 21 days of calving 

Less than 5% incidence of calving difficulty (difficult birth) 

To the above list we can add targets for replacement heifers (these will be discussed in 

more detail later). 

Mate heifers for only 42-45 days (2 cycles) with a target 85% in calf rate 

70% calve in first 21 days of mating 

less than 10% incidence of calving difficulty 

Note - An oestrous cycle is about 21 days and 2 cycles about 42 days. Some farmers also 

mate cows for 2½ cycles i.e. 7½ weeks = 52 days to ensure a cow that cycles on day 22 

which is not mated and cycles 22 or 23 days later has an equal chance of being mated 

twice. If a 42 day mating was used this would not be the case and the cow would have only 

one opportunity to be mated. 

Another reason for restricting mating to 2½ to 3 cycles (53-63 days) is shown in Table 4.1. 

In this example the herd that was mated for 105 days (5 cycles). The entire herd was 

cycling when the bull was introduced, and a 60% conception rate was assumed (normal for 

natural mating, usually ranges from 50% to 75%). After 63 days of mating 94% of cows 

would be pregnant, but it would take another 42 days on average for the remaining cows to 

get pregnant. 


49 

Table 4.1: Pattern of mating and conception during a 105 day mating period - 

assuming a 60% conception rate (Morris 1998). 

Days since start of 

joining 

21 

42 

63 

84 

105 

0-105 

Number on heat each 

21 days 

100 

40 

16 

6 

2 

164 

4.3 Reproductive management of beef cattle 

4.3.1 Management and age at first calving of heifers 

Number pregnant each 

21 day period 

A recent Meat & Wool New Zealand survey (Heuer, 2007) suggests about 55% of beef 

heifers are first mated at 15 months of age. It is usually more profitable to calve heifers first 

at two years of age than 3 years. 

The main reasons for this are because: 

Lifetime output is increased by about 10% (an extra 0.7 calves or 150kg of calf 

weaned) 

Land use for heifer rearing is reduced by nearly 50% 

Information for selecting replacements is available much earlier in a female’s life. 

This information is particularly useful if more heifers are mated than are required as 

replacements 

Profitable Farming of Beef Cows Chapter 4: Reproduction in the beef cow herd 

60 

24 

10 

4 

2 

100 

Increased rate of genetic gain (especially for bull breeding herds).

50 

The main reasons for farmers failing to adopt the practice of 2 year-old calving in 

New Zealand beef cow herds are: 

Poor performance at the next mating (often one of the costs of 2 year-old calving is 

a 5-10% lower pregnancy rate in the next breeding period) 

Fear of increased incidence of calving difficulty (dystocia) and associated increase 

in calf mortality and possibly heifer mortality 

A failure to achieve target liveweights during rearing and at mating, thereby 

jeopardising subsequent reproduction performance 

Concern that the heifer’s mature size and productivity will be reduced. 

Stage of farm development - on harder hill country or less developed country (in 

terms of pasture production and quality), heifers may fail to reach the required 

mating liveweights 

Reduced management flexibility (pregnant heifers require extra feed and there is an 

extra mob to manage) 

Overall increased management skills are required 

While the evidence consistently favours mating heifers at 15 months of age to increase 

production and profit per animal or per herd, the evidence is less convincing when 

accounting for feed costs required to achieve this increase. 

A New Zealand study (Table 4.2) found that mating heifers first as yearlings as opposed to 

two years of age resulted in efficiency increases (expressed as kg of calf weaned per kg of 

cow wintered) of 2% for Angus dams and 6% for Hereford x Friesian dams (H x F). For 

both dam breeds, 7% fewer cows were run per hectare when mating heifers first at 

15 months of age, reflecting higher winter liveweight gains and feed requirements of mated 

yearling heifers. 


51 

Table 4.2: Effects of age at first mating and cow breed on numbers of cows and 

replacements wintered, winter feed requirements and calf production when considered at 

the same winter feed requirement (adapted from McMillan and McCall 1991). 

Number wintered 

(MA cows plus replacement heifers) 

Feed requirements 

(kg DM/animal/day) 

Angus Hereford X Friesian 

2 year old yearling 2 year old yearling 

100 93 89 83 

4.4 4.7 4.9 5.2 

Females joined 70 74 61 66 

No. calves born* 70 75 61 68 

Average calf weaning weight (kg) 161 165 190 194 

Efficiency ratio 

(total kg of calf weaning wt) 

100.0 101.7 108.2 114.8 

* Number of calves weaned per number of females wintered (including replacement heifers) 

Higher efficiency of H x F dams compared with Angus dams for yearling compared with 

2 year mating was due the to lower relative performance of Angus heifers compared with 

mixed age cows. Angus dams weaned 58% calves per heifer joined as yearlings and 83% 

calves weaned per cow joined for mixed age cows whilst H x F dams weaned 75% and 85% 

respectively. Using these parameters, a higher proportion of non-pregnant Angus than 

H x F heifers would be wintered. From this study, the authors suggested that benefits of 

changing from 2 year to yearling mating would be minimal unless accompanied by a switch 

to more productive breeds. In a follow-up study McMillan and others (1992), found an 8% 

increase in herd efficiency (weight of calf weaned per unit of winter feed required) was 

obtained when Angus heifers were mated first as yearlings as opposed to 2 years of age. 

The increase in efficiency for this herd under yearling mating was comparable to the H x F 

in the previous study. 

A prerequisite to mating heifers at 15 months to calve at 2 years of age is that the heifer has 

attained puberty. Puberty in the heifer is marked by the start of regular oestrous activity, 

associated with ovulation. All heifers should reach puberty well before the planned start of 

mating, so each has exhibited at least one "heat" before the start of mating. This will ensure 

there is a high probability that all will be mated and conceive during the first 6 weeks of 

mating. 


52 

4.3.1.1 Critical minimum weight 

Heifers mated as yearlings have a requirement for high quality feed if they are to reach a 

critical minimum weight (defined as the weight at which 85% or more heifers get pregnant in 

a 42 day mating period) and rebreed successful. Under harder hill country this condition 

might not be met. Target live weights for mating British breed heifers at yearling age are 

shown in Table 4.3. From New Zealand breed comparisons, Continental x British breed 

heifers were on average 30 days older and 30 kg heavier at puberty than straightbred 

British breed heifers, suggesting higher target live weights for these later maturing breeds. 

4.3.1.2 Checklist for successfully mating heifers at 15 months 

Set a growth pathway from weaning to a minimum joining live weight at 15 months 

(Table 4.3). An appropriate minimum target might be 270 kg for Angus and 300 kg 

for later maturing breeds 

Mate heifers for 42 days – aim for a target pregnancy rate of 85% 

Mate heifers at the same time as older cows as earlier mating can result in below 

target pregnancy rates at the next mating due to delayed returns to oestrus (see 

later) 

Mate more heifers than are required as replacements and cull empty heifers 

following pregnancy testing. Non pregnant at yearling breeding is highly repeatable 

Cull late calvers to ensure that 70% calve in the first 21 days 

Understand the concept of Expected Breeding Values (EBVs) and select service 

sires from easy calving breeds/herds and with a high direct calving ease EBV. If 

these EBVs are not available select sires with below breed average birth weight 

EBVs, below breed average gestation length EBVs but with above breed average 

200 or 400 day weight EBVs (‘curve bender bulls’) 

Use sires from the same or smaller breeds. 

Provide assistance at calving where necessary 

Run as separate group until second calving 

Strive for 90% calf survival to weaning 

At least 90% of heifers should be pregnant again as R-3 year olds 

There are additional feed costs, when mating yearling heifers. If yearling heifer in-calf rates 

are less than 70% there may be no benefits compared with calving first at 3 years. Every 

farm needs to be evaluated separately to ensure benefits are realised. 


Table 4.3: Target live weights for mating Angus or Friesian x Hereford/Angus cross 

heifers first at 15 months of age 

4.3.2 Time and duration of calving 

53 

Age (months) Weight (kg) 

Weaning 6 200-220 

1 st winter 10 220-240 

1 st mating 15 270-300 

2 nd winter 22 400-450 

Pre-calving 24 440-480 

2 nd mating 27 420-450 

It is important to distinguish between mating date (the day the cow is mated) and joining 

date (the day the bull is put in with the cows). There are risks associated with too early a 

mating date and likewise too late a mating date. 

Risks associated with too early a mating date are: 

Cows calve before spring flush 

There is greater requirement for saved (winter) pasture pre-calving 

Cows are usually in a lower condition score at joining 

Cows exhibit longer post-partum anoestrus intervals 

Cows often calve later in the following year 

Risks associated with too late a calving: 

Waste of (surplus) spring pasture 

Smaller calves at weaning 

Peak lactation is reached too late in the summer-dry risk period 

Reduced opportunities for re-mating 

Reduced lifetime calf output 

Generally (except for South Island high country) beef cows are typically planned to calve at 

the same time as, or before lambing. Many farmers are now questioning this as being too 

early and in terms of profitable use of winter feed and efficient reproduction this is certainly 

the case. Time of mating for heifers is important and if they are mated too early in spring 


54 

they will have less time to reach puberty and the required "critical minimum mating weight". 

In reality, most beef cows are run with sheep and the optimum time to mate depends on 

individual property features as described in Table 4.4. 

Table 4.4: Factors indicating later calving would be recommended. 

Factor Trend in factor Recommendation 

Cattle : sheep ratio High ratio Later calving 

Stocking rate High Later calving 

Cow genotype More productive Later calving 

Cow management 

Cows consume spring surplus pasture and 

are used to maintain pasture quality 

Later calving 

Calving pattern is an excellent guide to the suitability of mating date. If less than 50% are 

calving in the first 21 days of calving then mating date is probably too early. The target is 

60% of cows and heifers mated in first 21 days of mating – so that at least 60% should 

calve in the first 21 days of calving. It is a relatively simple procedure to collect this 

information. Simply count the number of calves born per week and then plot them over 

21 day periods throughout the calving period. This will give a detailed picture of how the 

previous year’s mating went. 

4.3.3 Age of cow and reproductive performance 

Young cows often have a lower average reproductive performance than older cows, 

although the extent of the difference can depend on breed type. Pregnancy rate increases 

up to at least 6 years of age, then remains stable until about 9 or 10 years of age, after 

which it starts to decline. 

The most comprehensive New Zealand study on age of cow and reproductive performance 

(7500 matings) is summarised in Table 4.5. Results suggest that beef cows in a mixed age 

herd should not be culled on age until they are over 10 years. 


55 

Table 4.5: Effects of cow age at mating on pregnancy rate, ease of calving and calf 

weaning %. Source: Morris (1998). 

Age at mating 

No. of 

records 

% cows 

pregnant 

% calved without 

difficulty 

% calves weaned 

per female/mated 

15 months 2711 77 84 63 

27 months 2022 74 92 63 

3 years 1803 82 95 74 

4 years 1639 89 96 83 

4.3.4 Calving difficulty (dystocia) 

Calving difficulty or dystocia has a major effect on the subsequent production and 

reproductive performance of the affected cow. The incidence of calving difficulty varies and 

is probably responsible for up to two thirds of calf deaths in beef cow herds (average calf 

mortality in herds is 0 - 15%). The incidence can be much higher in first calving heifers and 

can be quite low

56 

Breed of dam - the British beef breeds (Angus and Hereford) tend to have less 

incidence of calving difficulty than dairy or continental beef crosses. 

Gestation length - an extended gestation length will increase birth weight. 

Season of birth - late season calvers tend to have higher birth weights than animals 

that calve in late winter early spring. 

Table 4.6 gives some comparative data on birth weight, gestation length, incidence of 

calving difficulty and calf mortality from the only comprehensive breed evaluation carried out 

in New Zealand. Note the relationship between birth weight, gestation length and incidence 

of calving difficulty and calf death. One of the reasons that calving difficulty is high when 

European continental breeds are used is the increased gestation length of calves sired by 

those bulls. 

Figure 4.5: Changes in birth weight EBV through time in US beef breeds 

Source: Kuehn and others (2008). 

The most practical way to control or minimise calving difficulty is via bull breed and birth 

weight EBV. It is also crucial that EBV accuracy is taken into account. Figure 4.5 shows 

the results of efforts by U.S. breed societies to control birth weight EBVs. The results show 

that progress can be made in controlling birth weight while still maintaining progress in say 

yearling weight (not shown here). These effects will filter down to New Zealand through the 

importation of genetics from Australia and the US by New Zealand beef breeders. Many 

New Zealand breeders also apply similar selection processes to their breeding 

programmes. 


57 

Table 4.6: The effects of breed of sire (averages of mating to both Angus and Hereford 

dams) sex of calf and age of dam on calf birthweight, gestation length, incidence of dystocia 

and calf deaths. (NZ data: Baker and others 1990). 

Sire 

Birthweight 

(kg) 

Gestation 

(days) 

% Calving 

difficulty 

% Calf deaths 

to 48 days age 

Jersey 27.4 283 0.9 1.8 

Angus 29.6 281 3.6 4.1 

Hereford 31.6 282 2.3 3.6 

Friesian 31.9 280 4.6 2.9 

Limousin 32.7 287 5.5 3.8 

Blond d'Aquitaine 33.8 288 10.4 4.8 

Simmental: 

- German 33.5 285 7.3 5.2 

- Austrian 34.4 286 9.6 10.5 

- French 35.0 287 10.9 4.7 

- Swiss 35.0 286 10.8 6.4 

South Devon 34.4 286 7.1 5.0 

Charolais 35.7 285 17.7 11.2 

Chianina 36.8 288 15.1 6.1 

Maine Anjou 35.7 285 13.7 8.4 

Sex of calf 

Male 34.5 286 12.1 7.4 

Female 32.3 284 5.0 3.9 

Age of cow at calving (years) 

3 32.0 285 13.8 8.6 

4 33.5 284 6.8 4.5 

Older than 4 34.7 285 5.0 3.8 


4.3.5 Post-partum anoestrus interval 

58 

The post-partum anoestrous interval (PPAI) is the time between calving and the first oestrus 

after calving. Post-partum intervals are of prime importance in cattle where gestation takes 

up to 282, days thereby leaving only 83 days to re-commence oestrous cycles and to 

establish pregnancy if calving date is to be maintained. 

The duration of the post-partum interval in beef cows is determined by: 

1. Date of calving: Cows which calve earlier in the late winter/spring calving season 

tend to take longer to experience their first post-calving oestrus than cows that calve 

later in the calving season (Figure 4.6) Heifers can take about 7 days longer to 

cycle for every 10 days earlier calving. 

2. Age of cow: In one study for example, PPAI for 2 year old cows was 90 days vs. 

63 days for older cows. The practical significance of this effect is that the benefits of 

mating heifers 3 weeks ahead of the mixed aged cow herd are often negated by 

their longer PPAI. Research indicates that the range in PPAI is as shown: 

a. 2 year old heifers 72 to 111 days 

b. mixed aged cows 57 to 71 days 

3. Breed of cow: In another study, Friesian cross heifers had an average PPAI of 

90 days vs. 81 days for Angus heifers. This breed difference is likely to be related 

to increased milk production and lighter condition (nutritional stress) in beef x dairy 

animals. 


59 

Figure 4.6: The effect of calving date in spring calving cows on post-partum oestrus 

interval (PPAI). 

Table 4.8 provides an example of the relationships between calving date and feeding level 

during the post-partum period. A high level of feeding after calving does not fully 

compensate for an early calving date. In contrast a medium-nutrition regime is adequate for 

later calving cows. Photoperiod has some influence on PPAI with increasing day length 

tending to reduce PPAI. However, this is difficult to quantify in its own right because 

increasing day length is closely linked to increasing pasture growth rates. 

Table 4.8: The effect of calving date and post-calving nutrition levels on PPAI (days) 

Early calving Late calving 

Calving Period July 21 – Sept 15 Sept 9 – Oct 10 

High nutrition 67 57 

Medium nutrition 83 62 

Season of birth can determine PPAI. In spring-calving herds the interval ranges from 65-90 

days while for autumn calving herds it is 31-51 days. 

Cow condition, liveweight and liveweight gain post-calving are major determinants of the 

post-calving interval in beef cows. In one trial an extra 20 kg post-calving liveweight was 

associated with a 7 day shorter interval in heifers, compared with only 2 days in adult cows. 


4.3.6 Bull management 

60 

Most New Zealand beef cows are mated using natural mating with artificial insemination 

being confined mainly to the bull breeding industry. Factors that contribute to the outcome 

of natural mating include bull age, bull soundness and fertility, breed of bull and bull to cow 

ratio. 

Age: Puberty is dependant on nutrition, age, breed. This occurs in males for 

New Zealand breeds at around one year of age (older in some continental breeds). 

Yearling bulls make satisfactory herd sires if they are adequately grown (>350kg) 

and run with no more than 25-30 cows each. Scrotal circumference is a good 

indicator of puberty and bulls with a scrotal circumference less than 30 cm should 

not be used. 

Bull-to-cow ratio: Little New Zealand data exist as to the effects of bull to cow ratio 

on herd pregnancy rate. It is normal practice for one bull to be joined with to 30-50 

cows. If farmers wish to use fewer bulls of higher genetic merit, a higher ratio can 

be used provided the bull is physically fit enough. 

Soundness and fertility: Mating cow herds on undulating to steep hill country poses 

extra problems for bulls. They must be able to seek out, find and mate oestrus 

cows on broken terrain. Unstable footing during mounting can potentially lead to 

damage to limbs, joints and genitals. Every bull used needs to have a yearly 

breeding soundness evaluation 30-60 days before the start of the breeding season. 

Currently attempts are being made by the beef cattle stud industry in consultation 

with the Sheep and Beef Society of the New Zealand Veterinary Association to 

standardise a presale or pre-season bull soundness examination which could 

include the items shown below: 

Inspection for structural and inheritable faults 

Examination/palpation of reproductive organs 

Temperament, locomotory system assessment 

Serving ability test 

Diagnostic tests for BVD, EBL, Camplyobacter, Trichomonas 

Semen evaluation (gross and morphology) 

The degree to which these tests are used in the industry will depend on the level of risk 

associated with using unsound bulls and animal welfare issues associated with some of the 

testing procedures. There is little hard information on fail rates for the tests. If tests are 


61 

carried out for the first time in several years, anectdotal evidence suggests at least 25% of a 

bull team could fail but with much lower fail rates in subsequent years. 

There is variation in the assessment of the true level of risk associated with the prevalence 

of semen faults in young bulls. Tattersfield and others (2006) found 0.6% of 175 sale bulls 

surveyed were unsound on semen morphology with a further 10.5% temporarily unsound 

and requiring repeat semen testing. They also found 21% of mixed age bulls failed this test 

versus 5% of 2-year old bulls. There is variation within populations of bulls. Younger bulls 

tend to have fewer semen quality issues than older bulls. It is impossible to state 

categorically that a bull is fertile but it is possible to minimise the risk. Semen testing is not 

common in commercial herds. Clearly, where mixed age bulls are to be single sire mated 

there are advantages of including semen evaluation in an attempt to mitigate risk. 

As a bull ages, the risk of failure, for the service test in particular, also increases. 

Procedures for assessing the mating potential of bulls have also been developed in 

Australia. The "serving capacity test" provides an indication of the ability of a bull to 

successfully mate a given number of cows over a 3 week period. Serving capacity testing is 

not recommended by Meat & Wool New Zealand for welfare reasons; a modified form called 

serving capability testing has been developed by the New Zealand Veterinary profession. 

This test simply determines if the bull is capable of mating an oestrus cow and does not 

rank bulls. It is a less stressful test and is valuable in detecting arthritis and joint problems 

with older bulls. 

In practice, most bulls are used in syndicate matings (i.e. more than one bull per mating 

mob) with 2 to 3 bulls per 100 cows. While this is an acceptable practice it uses a higher 

proportion of bulls than is needed to achieve a high pregnancy rate. The extra bulls are an 

insurance policy against any one bull failing during the mating period. 

Bulls need to be in good condition (CS 3.5 (6 to 7)) but not over-fat prior to the mating 

season. Check bulls at least twice a week during mating to observe them walking and to 

check for anything unusual. If possible, watch bulls actually mating. It is a good idea to 

have a spare bull available to replace any bull that breaks down over the mating period. 

Some farmers rotate bulls after one cycle (or even 1 week) of mating. This is especially 

important in single sire mated groups and acts as insurance against bull infertility. 


62 

When a new bull is purchased remember it needs time to adjust to its new surroundings. 

The bull should be run with a steer or old cow once it arrives at its new home, never run 

with older bulls. Sometimes bulls purchased have not cut their second teeth - so feed 

should be plentiful as this is a stressful time and they can loose condition. 

4.3.7 Pregnancy diagnosis 

Determining pregnancy in cattle is an important management tool. The advantages of 

knowing the pregnancy status of a beef cow herd are: 

Allocation of feed 

Saving feed by culling non-pregnant animals before the winter 

An experienced veterinarian can determine the age of the foetus if pregnancy diagnosis is 

done at the right time (8-12 weeks pregnant). This allows for prediction of calving dates and 

more precise allocation of feed in late pregnancy and early lactation. It can also assist in 

more efficient use of labour during calving especially if calves are tagged and weighed at 

birth 

4.3.7.1 Two methods of pregnancy diagnosis 

1. Palpation of the uterus and its contents: this involves inserting a gloved and 

lubricated arm into the rectum and feeling the reproductive tract. This was the 

most common method used in New Zealand and is performed 6 weeks (for 

heifers) and 8 weeks (for cows) after the bull is removed from the herd. 

2. Ultrasonic detection of the foetus and its membranes using a portable scanner is 

now the most common technique for determining pregnancy in cattle. Scanning 

is faster and less demanding physically than rectal palpation and is becoming 

the preferred technique. Scanning is done with a rectal probe. The technique is 

often performed between 6 to 8 weeks after mating and allows for manual 

checking of cows where either a foetus or an empty uterus cannot be visualised. 

Pregnancies can be detected as early as 35 days. However accuracy and speed 

of detection increases as pregnancies develop. At the other extreme, the later 

that testing is left after bull removal, the more manual checking may be required 

as pregnancies drop down over the pelvic rim beyond the reach of the probe. 

Foetal ageing can also be performed but requires training and practice. The 

most practical time for foetal ageing is when pregnancies are between 6 to 12 


63 

weeks of age. Depending on the length of the mating season, pregnancies can 

be split into mating cycles, allowing for better feed allocation pre-calving. 

Scanning needs to occur 6 to 8 weeks after bull removal. A complicating factor 

is cows often are not weaned at this time requiring drafting of calves. Less 

desirably, they can run up the race with the cows as they are usually large 

enough by then to handle this. 

Foetal sexing is possible using ultrasound but is technical and specialised. It is 

best performed at 60 to 80 days of conception and requires a high resolution 

scanner. Sequential testing may be required due to foetal orientation and 

accurate mating records are necessary. It is more time consuming and 

laborious and requires more experience. 

Under good conditions with a long race holding up to 10 cows and when 

pregnant/non pregnant diagnosis only is required, up to 200 cows an hour can 

be scanned. As the dry rate increases this slows down the speed of operation. 

Foetal aging also reduces speed to 80 to 100 cows an hour. However speed of 

scanning is very variable under field conditions as many factors can influence 

operator speed e.g. light, cow temperament, faecal composition, stage of 

pregnancy, race length, race width, cat walk height, number of staff present. In 

long races it is preferable to work from front to back to avoid having cows 

stacking on top of each other. A dividing gate half way along can help alleviate 

this problem as does race width (650 to 700 mm is optimum). Right handed 

operators prefer the cat walk on the right hand side of the race when looking 

forward. The top rail should not be too high above the cows, usually level or 200 

mm above the cow’s back. The most common height for cat walks is 600 mm 

with the top rail 900 mm to 1 meter above this. A generous cat walk width of 

750 mm to 1 meter allows for operator safety and so people can pass each 

other comfortably. 

4.4 New reproductive technologies for use in beef breeding cows 

A reproductive technology can be defined as any technology that impacts on the 

reproductive performance of breeding cow or a herd of breeding cows. This definition 

includes technologies which impact on the number of calves produced as well as the weight 

of the calves at weaning time. Reproductive technologies can impact on cows or herds in a 


64 

variety of ways. They can improve calf productivity (number and weight of calves weaned), 

herd management and genetic gain. Risks, costs and the level of technical input vary for 

the options available. Most, if not all, of these technologies have direct application in the 

dairy herd and this is where most reproduction technologies were first developed and 

established. 

Low technology options are mainly management options and tend to be low cost, low risk 

and generate low to medium returns. These include the already discussed yearling heifer 

mating system, highly productive breeding cows e.g. dairy x beef bred cows (Hereford x 

Friesian), adjustments to the date of calving, pregnancy diagnosis and foetal calf ageing. 

Medium technologies have a need for high technological input and are more costly. The 

relevant technologies here are oestrus synchronisation, multiple suckling using an 

additional foster calf, or the use of artificial insemination. 

High technology options are costly and require a high level of technological input. They 

include induction of twin pregnancies using embryo transfer, changing the sex ratio of 

calves, and cloning. 

Some technologies are discussed in more detail below. 

4.4.1 Oestrus synchronisation 

This is often a prerequisite to the use of AI and embryo transfer. In addition it may be used 

to facilitate appropriate feeding and calving management since cows will all be at the same 

stage of pregnancy. McMillan (1994) found that synchronisation of oestrus changed the 

calving distribution with an earlier median calving date by about 10 days in synchronised 

heifers. The effect of this earlier calving date was an improvement in calf weaning weight of 

12 kg. Synchronisation costs are likely to be around $15 per cow and the 12 kg extra calf 

weight covers these extra costs at a weaner price of $1.25/kg liveweight. 

4.4.2 Artificial insemination (AI) 

This can be used to obtain access to bulls which would otherwise not be available (e.g. 

bulls from overseas). AI is used to improve rates of genetic gain, or to limit sexually 

transmitted diseases. The use of AI in beef cows in New Zealand is mainly limited to bull 


65 

breeding herds and is likely to remain that way in the near future. The intensive labour input 

required for the identification, isolation and handling of cows on heat is not available in most 

commercial extensively run beef cow herds. It is also difficult to maintain an adequate feed 

supply for cows and calves close to cattle yards for the duration of the AI programme. 

Another potential problem that limits the increased use of AI in beef cow herds is lack of 

suitable progeny tested bulls. Unlike the dairy industry, where there are industry wide 

progeny test schemes run by artificial breeding companies, there are no such schemes in 

the beef industry and it is up to individual breeders or groups of breeders to progeny test 

sires, using for example the BREEDPLAN scheme (Chapter 6). 

4.4.3 Producing twin pregnancies 

In cattle the natural twinning rate is 1% although Simmental herds may have up to 2.1% 

twinning rate. Twinning can be induced by embryo transfer using either two transferred 

embryos, or one transferred embryo to supplement the natural one produced by the cow. 

Up to 101 calves may be born from one round of transfer (range is 10–101, with the 

average 50-60). A second round of inducing twinning in cows which return to oestrus after 

the first round can produce another 20-30 calves. Researchers are also working on a 

vaccine to produce twinning in cattle. Selection is also possible but slow. Geneticists at 

Clay Centre, USA have bred a herd of twin calving cows who have a twin pregnancy rate of 

over 50% (Cummins and others, 2008). Any of the above methods should ultimately be 

able to achieve over 150 calves born per 100 cows. 

Even if twin pregnancies have been achieved, twinning in cattle is not straightforward. Calf 

losses at twin calving can be as high as 40%, mostly due to foetal malpresentation in the 

birth canal (causing calves to be born dead) and mis-mothering and poor colostrum feeding 

immediately after calving; often exacerbated, ironically, by high levels of human intervention 

at calving. Even so, a high level of supervision at calving is required to ensure high twin calf 

survival. If the twin calves survive and are bonded to the cow and feed well, there should 

be few problems subsequently. Twins will wean at a weight that is over 60% of cow 

liveweight. 

For productivity reasons, some managers foster a second calf onto a single calving cow. 

This process is labour intensive immediately after calving and requires carefully followed 

protocols to avoid calf illness. Financially, twinning by fostering, or using multiple suckling 


66 

nurse cows can be very profitable, even after allowing for the extra labour required at 

fostering-on time. However, the practice has had only limited adoption in New Zealand. 

Three technical barriers have to be overcome at an acceptable price for twinning in beef 

herds to be a successful and profitable system: 

Cows routinely become pregnant with twins 

Cows deliver a high percentage of live twin calves at calving 

Twin calves have high survival and are illness-free in their first month of life. 

If the above obstacles were overcome, beef cow productivity and profitability would be well 

placed to show similar gains to those achieved by the New Zealand sheep industry in the 

last three decades. 

4.4.4 Changing average calf sex ratio 

Changing the average calf sex ratio could influence the economics and genetics of livestock 

production in New Zealand. For example, a beef farmer could breed 80 steers and 20 

replacement heifers from the 100 cows, thus increasing the value of their weaners (steers 

or bulls are more valuable than heifers). However, the heavier birth weights of males can 

lead to increased mortality rates from calving difficulty, especially in calving heifers, so this 

would need to be allowed for. The technique is available commercially in New Zealand but 

its adoption rate is still low due to technical difficulties and cost. 

Sperm sexing occurs where the populations of x (female) and y (male) chromosome 

bearing sperm in a semen sample are separated. At present they can be separated with 

about 90% accuracy, using a fluorescent dye where the x chromosome absorbs more of the 

dye than the y chromosome. The dyed sperm are then passed through a laser beam in a 

sorter one by one. This gives them a charge, either positive or negative and they then pass 

through an "electric gate" which sorts them into x and y groups based on their electric 

charge. This method is relatively slow sorting only 100 sperm per second (Note that one 

insemination dose for a cow, using frozen semen, requires 10 million sperm). 

Sexed sperm is more likely to be used in laboratory based in vitro fertilisation (IVF) and 

embryo production (IVP) to generate sex selected calves. This is a technology that will 

probably be first used in the dairy industry where female calves are produced at initial 

matings and the males at later matings. 


4.4.5 Cloning 

67 

Nuclear transfer (NT) cloning is an assisted reproductive technology which creates an 

animal that is a genetic copy of the donor cell genome used in the procedure. Simply, it 

involves microsurgery under the microscope to introduce the nucleus of a donor cell into the 

cytoplasm of a mature cow’s egg that has had its own nuclear DNA removed. This 

reconstructed 1-cell embryo is then artificially activated to commence development and is 

grown in the laboratory for 7 days until it reaches the blastocyst stage (around 120 cells) 

and can be transferred to the uterus of a recipient cow. Nuclear transfer technology has the 

potential to replicate cloned animals from outstanding embryonic or adult genotypes, 

including resurrecting animals for breeding after post-slaughter carcass assessment. 

Cloning would be an attractive alternative to artificial insemination, which is not widely 

adopted on extensive beef farms. 

Although improvements have been made, the NT process remains inefficient. Presently, in 

cattle, about 10% of NT embryos transferred to recipient cows result in viable calves. High 

pregnancy losses throughout gestation and after calving reduce the acceptability of this 

technology. Continued research aims to understand how it is biologically possible to take a 

specialised cell from the body of a donor animal and generate a normal cloned animal. 

Importantly, the sexually reproduced offspring derived from cloned parents appear normal. 

This provides confidence for the main potential application of NT in agriculture; that is, the 

production of cloned sires from genetically elite males for natural mating, to effectively 

disseminate genetic gain. Nonetheless, the integration of cloning into beef farming systems 

remains a future prospect dependent upon overcoming existing technical and biological 

barriers, in addition to gaining widespread international regulatory and consumer 

acceptance. 

4.4.6 DNA parenting 

Technologies using DNA parenting are used, albeit sparingly. Some breed societies 

require mandatory DNA parentage verification for breed registration purposes. (It is a 

requirement for all 2008 born Angus calves if they are to achieve breed registration). In 

future this DNA testing could be extended to allow whole genome scans or single gene 

tests to be run. 



68 

Anon. 2002. Bull Selection. A Beef Council Bull Publication. Available from Meat & Wool 

New Zealand, PO Box 121, Wellington, New Zealand 

Baker, R.L.; Carter, A.H.; Morris, C.A.; Johnson, D.L. 1990. Evaluation of eleven cattle 

breeds for crossbred beef production; performance of progeny up to 13 months of 

age. Animal Production, 50: 63-77. 

Cummins, L.J.; Morris, C.A.; Kirkpatrick, B.W. 2008. Developing twinning cattle for 

commercial production. Australian Journal of Experimental Agriculture, 48: 

930-934. 

Heuer, C. 2007. Management of beef cattle for high fertility. Part 4: Association between 

farm management practices and beef cow fertility. Final Report to Meat & Wool 

New Zealand, PO Box 121, Wellington, New Zealand. 

Hughes, P. 2007. Evaluation of Bulls for Breeding Soundness: The Society of Sheep and 

Beef Cattle Veterinarians NZVA Newsletter 32: 43-44. 

Kuehn, L.; van Vleck, D.; Thallman, M.; Cundiff, L. 2008. Across-breed tables for 2008 with 

year 2006 Angus base. Slides presented at the BIF Conference. 

http://www.bifconference.com/bif2008/ppt/LarryKuehn_GP.pdf. 

McMillan, W.H. 1994. Current and emerging reproductive technologies for beef breeding 

cows. Proceedings of the New Zealand Society for Animal Production 54: 

345 - 350. 

McMillan, W.H.; McCall, D.G. 1991. Are yearling heifers mated and more productive cow 

breeds worthwhile use of winter feed? Proceedings of the New Zealand Society of 

Animal Production, 51: 265-269. 

McMillan, W.H.; Morris, C.A.; McCall, D.G. 1992. Modelling herd efficiency in liveweight 

selected and Angus control cattle. Proceedings of the New Zealand Society of 

Animal Production, 52: 345-350. 

Morris, C.A. 1998. Reproductive management of beef cattle. In Reproductive 

Management of Grazing ruminants in New Zealand. Ed. E.D. Fielden and 

J.F. Smith. Occasional Publication 12: 145-156. Published by the New Zealand 

Society of Animal Production. 


69 

Morris, C.A.; Packard, P.M. 1985. Progress with Beefplan. In, 1984-85 Annual Report of 

the Ruakura Animal Research Station (Genetics Section), Ministry of Agriculture & 

Fisheries, Hamilton, New Zealand, pp.76-77. 

Parkinson, T.J.; Bruere, A.N. 2007. Evaluation of Bulls for Breeding Soundness 1 st Edition 

Publication No. 262 Published by VetLearn, Massey University, Palmerston North. 

ISBN 978-09583634-2-0. 

Smeaton, D.C. 2000. Management and profitability of multiple pregnant/suckling beef 

cows. A producer’s guide. A booklet available from Meat & Wool New Zealand, 

PO Box 121, Wellington, New Zealand. 

Taylor, R.E.; Field, T.G. 1999. Beef Production and Management Decisions. Third Edition. 

Publ. Prentice Hill, New Jersey, pp 714. 

Tattersfield, G.; Heuer, C.; West, D.M. (2006). Bull Soundness Examinations. Current 

Research and Written Guidelines: Proceedings of the Society of Sheep and Beef 

Cattle Veterinarians of the New Zealand Veterinary Association 36:123-126 


Summary 

70 

Chapter 5: Cow health 

Cattle are generally very healthy, but there are some animal health problems that can occur 

in beef cows. This chapter deals with the more common areas. 

Hypomagnesaemia or grass staggers is associated with low levels of magnesium in the 

blood, which occurs in pregnant and/or lactating older cows. The incidence is relatively low 

at 1 to 2% annually but major outbreaks can occur in individual herds. Feeding and 

management systems have been developed which can reduce the incidence of grass 

staggers. 

The essential elements of such systems are: 

Calving to coincide with the onset of the spring flush of growth 

Feeding cows well around calving (potentially at the expense of other stock classes) 

Supplementation with magnesium 

Facial eczema is caused by the mycotoxin called sporidesmin which is produced by the 

pasture based fungus Pithomyces chartarum. The consequences of facial eczema range 

from poor performance through to death, depending on the severity of liver damage. The 

main risk period is after warm humid weather (usually between January and April) in the 

North Island. Control and treatment is achieved by monitoring and predicting danger 

periods of high spore counts and or administering zinc salts. Facial eczema resistant stock 

can be farmed in susceptible areas as resistance is relatively highly inherited. 

Bovine Viral Diarrhoea (BVD) is a complex disease that affects cattle reproductive 

performance. Around 65% of New Zealand beef cattle herds have active BVD infection, 

and 80 to 90% of herds have had exposure. BVD infection in adult cows can cause 

reproductive wastage, weight loss and reduced milk yield. In young stock, BVD can result 

in nil or poor weight gain, loss of body condition and the premature death of “Persistently 

Infected” (PI) animals. Control is complex. 

Other disease problems discussed include nitrate poisoning and bloat. These occur 

infrequently but can be very damaging and difficult to manage when they occur. 

Profitable Farming of Beef Cows Chapter 5: Cow health

71 

TB in cattle is a disease of significant economic importance in New Zealand but is not 

discussed in this chapter. (Refer Further Reading). 

5.1 Grass staggers (Hypomagnesaemia) 

5.1.1 Overview 

Hypomagnesaemia (also known as hypomagnesaemic tetany or grass staggers) is a 

nutritional disorder associated with low levels of magnesium in the blood. It is confined 

mainly to pregnant and/or lactating cows, with clinical cases showing various gradations of 

behaviour from a slightly disjointed gait and fine muscle tremors to violent convulsions and 

sudden death. While surveys have shown that the incidence is relatively low, fluctuating 

between 1% and 2% of cows annually, major outbreaks can occur in individual herds with 

between 10-30% of the animals showing clinical signs or being found dead. The economic 

importance of this disorder stems from both impaired productive performance in animals 

suffering from hypomagnesaemia, and a high death rate amongst those affected by clinical 

tetany. Though deaths from grass staggers can occur at any time from late autumn to early 

spring, the greatest concentration of cases is usually over the calving period. 

The disorder is related to a wide variety of nutritional, environment, and management 

factors. These include: underfeeding, grazing lush spring herbage, abrupt changes in diet, 

chemical composition of the feedstuff, fertilising practices, age and body condition of cow, 

physiological state and a variety of stresses such as rough weather, handling, yarding and 

trucking. 

The precise physiological or biochemical changes involved in the onset of 

hypomagensaemic tetany or grass staggers, and the reasons why many animals can 

tolerate extremely low serum magnesium concentrations for long periods without exhibiting 

symptoms, is obscure. Under field conditions, the disorder frequently appears to be 

triggered by stresses such as calving, oestrus, rough weather and excitation of animals 

already with low magnesium levels because of diet. Feeding and management systems 

have been developed which can reduce the incidence of grass staggers. The essential 

elements of such systems are some or all of: 

A timed mating period (7-9 weeks) to enable calving to coincide more closely with 

the onset of the spring flush of growth 


72 

During late autumn/winter, feeding cows at consistent levels to avoid sudden 

changes in energy supply from one day to the next 

Feeding cows to appetite on saved pasture from 2-3 weeks prior to the onset of 

calving. While ad libitum feeding may not always be possible, feed supplies should 

be manipulated and pasture allowances adjusted to provide intakes of at least 

8 kg DM/cow/day. This saved feed may be costly unless the cow calves close to, or 

on the spring flush 

Supplementation with magnesium salts or oxide 

Dietary changes (e.g. mature to immature herbage or pasture to hay and vice versa) appear 

to be one of the most significant factors in inducing hypomagnesaemia and tetany under 

farm conditions. Feed type changes frequently result in rapid and substantial falls in serum 

magnesium concentrations and outbreaks of clinical tetany within 3-14 days, even under 

apparently high levels of feeding. 

5.1.2 Magnesium supplementation 

Oral magnesium supplementation can be very effective in preventing grass staggers in beef 

cattle. Magnesium-rich materials most suitable for this purpose are magnesium oxide 

(>50% Mg), Epsom salts (10% Mg) and magnesium chloride (11% Mg). The means of 

administering magnesium supplement to beef cattle are: 

Treated hay - Feeding hay or silage treated with magnesium oxide is one of the cheapest 

and most effective means of administering supplementary magnesium. Care must be taken 

to ensure that all cows receive their daily ration, that a minimum quantity of hay (

73 

membranes of cattle. The cows generally react by shaking the hay vigorously and dislodge 

further quantities of the supplement. 

Pasture dusting - Dusting pastures lightly with calcined magnesite (magnesium oxide) 

prior to grazing is another very reliable method of ensuring that all cows consume at least 

some supplementary magnesium. The technique is particularly useful during sudden 

emergencies, and where cows are being strip grazed on saved pasture. 

Extensive trials have shown that dusting pastures at weekly intervals with ½ kg calcined 

magnesite per cow can maintain serum magnesium levels close to or within the normal 

range under a wide variety of weather conditions, pasture lengths and grazing pressures. 

Calcined magnesite (60 mesh) is preferred to Causmag because it is slightly coarser and 

will flow more readily through spinners and other topdressing equipment. The area to be 

grazed in the coming week should be dusted early in the morning, when the dew on the 

pasture will improve adhesion, and the area should then be ration grazed to prevent 

physical agitation and dislodging of the calcined magnesite. Dusted pastures can tolerate a 

fair amount of light rain, but should be re-dusted after heavy falls (more than 40-50 mm 

within 2-3 days of application). 

The pasture dusting technique tends to be more difficult to operate under extensive grazing 

conditions. However, the method can still be very effective, providing application rates are 

increased to ¾ to 1 kg calcined magnesite/cow/week. There is no real need to cover every 

square metre of the area to be grazed. The material can be applied in strips, or smaller 

areas dusted by hand each day. 

Water trough treatment - Treatment of drinking water with soluble magnesium salts such 

as magnesium chloride or Epsom salts at the rate of 60 g/cow/day can reduce the clinical 

incidence of grass staggers and generally increases mean serum magnesium levels in 

cattle by about 20%. The technique appears to be convenient and easy to operate, and for 

that reason is fairly popular with farmers. There are a number of factors which can 

influence the efficacy of the technique, and a clear understanding of these is essential 

before the method is adopted. 

Cows must not have access to untreated water and the method is not one that can be 

applied quickly. Cows need to be trained to accept the treated water at low concentrations 

over a 2-3 week period. The final treatment rate of 60 g/cow/day provides a lower 


74 

magnesium intake than desirable, but is the best compromise possible given the palatability 

and diuretic properties of these soluble magnesium salts. 

The technique also tends to be unreliable because of wide variations in drinking behaviour. 

Mean daily water intakes can range from above 40 litres/cow to less than 5 litres/cow 

according to weather conditions, and the dry matter content of the feed. Under very wet 

conditions many cows will go without drinking for up to two days. Water consumption is 

usually higher and more stable on rations composed largely of hay and mature pasture. 

The actual method of adding the magnesium salt to the drinking water is another factor 

which can affect the success of the technique. Stripping of the material from the trough by 

early drinkers can also be a problem where dilution is allowed to occur as the animals drink. 

Under these circumstances the dose should be split and added on two or three occasions 

during the day, or a trough dispenser used which allows a steady flow of material, and at 

the same time provides for a wide range of water consumption. 

Magnesium licks - Free access to magnesium licks may help limit the incidence of grass 

staggers under extensive grazing conditions where other methods of supplementation 

cannot be used. Animals need to trained to accept licks well before the critical period 

commences, and variations in licking behaviour between animals, and by the same animal 

at different times, can be an issue. Observations on licking behaviour of individual animals 

show that about 10% of a herd can be classed as non-lickers, a further 10-15% as very 

poor, and a small proportion as avid lickers who may consume excessive amounts and 

show obvious signs of scouring. The remainder of the herd usually exhibit a marked cyclic 

pattern of licking, with a number of animals licking vigorously for several days and then 

showing no interest for periods of 5-10 days or more. The cumulative effect of this 

behaviour is that about 25% of the herd receives virtually no magnesium supplement, and 

the serum magnesium concentrations in the remainder fluctuate widely. 

Magnesium bullets – Probably the most costly method of supplementation, the use of 

intra-ruminal slow release bullets can be very effective in extensively grazed herds. 

Depending on the severity of magnesium deficiency in the diet, the bullets may only need to 

be dosed into the older cows which are more prone to staggers. The bullet remains 

effective for about 4 weeks 


5.2 Facial eczema 

75 

Facial eczema is caused by the mycotoxin sporidesmin which is produced by the fungus 

Pithomyces chartarum. Sporidesmin is found almost entirely in fungal spores and is 

primarily toxic to the liver. Severe liver damage can occur. Animals may exhibit 

photosensitivity. The consequences of facial eczema range from poor performance through 

to death, depending on the severity of liver damage. 

Sheep are more susceptible than cattle primarily because they graze closer to the base of 

the sward and hence ingest more of the fungal spores. The main risk period is after periods 

of warm humid weather (usually between January and April) in the North Island. The 

periods of greatest risk occur when humidity is close to 100% and grass minimum 

temperatures are above 12ºC for three nights or more. These conditions are found when 

more than 4 mm of rain falls within 48 hours. Most regions provide spore counting 

information (some done by local veterinarians or farm consultants and reported in 

newspapers, etc.) Counts above 100,000 spores per gram of grass (wash method) are 

considered dangerous. See “Further Reading” at the end of this chapter for reference to a 

description of this spore counting method. 

Control and treatment is achieved by: 

Monitoring spore levels and predicting danger periods 

Not grazing at-risk paddocks and ensuring cattle do not graze pastures too hard 

Spraying pastures with fungicides to prevent fungal growth - costly but useful for 

prevention for high value animals e.g. breeding or service bulls 

Administering zinc salts - via drinking water, as a drench, or as a spray on pasture 

Time capsules – rumen bullets which provide effective protection for 5 weeks after 

being administered. 

Refer ‘Further Reading’ for more details. 


5.3 BVD in beef cattle 

76 

Bovine Viral Diarrhoea (BVD) is a viral disease that affects cattle. Recent New Zealand 

studies by Heuer and others (2008), have shown that BVD is extremely prevalent in beef 

herds. Around 65% of New Zealand beef cattle herds have active BVD infection, and about 

80-90% of herds have had exposure to BVD virus. Heuer and others found that between 

mating and pregnancy testing, BVD could reduce pregnancy rates by an average of 5% in 

herds that had active infection. The data also suggested that about 2% of New Zealand 

beef cattle herds will experience a decrease in pregnancy rates of at least 15% due to BVD. 

These figures do not include abortions that were not measured in this study 

Besides reproductive wastage, BVD causes weight loss and reduced milk yield. In young 

stock, (3-12 months age) BVD can cause a raft of ill effects, including nil or poor weight 

gain, loss of body condition and the premature death of “Persistently Infected” (PI) animals. 

BVD is also immunosuppressive; meaning cattle that have an active infection will have a 

compromised immune system that cannot protect them from other diseases. BVD infection 

has a major impact during mating and pregnancy. BVD causes infertility, embryo loss, 

abortions (slips), stunted and deformed calves, and the birth of dead calves. BVD does the 

most damage when it infects pregnant cows during early pregnancy. If a cow contracts 

BVD while she is pregnant, she may give birth to a PI calf. PI animals spread the disease 

and perpetuate it from one generation to another. 

It can take as little as one hour of contact with a PI animal to transmit BVD virus to an 

uninfected animal. Infection commonly occurs either through direct contact (nose to nose) 

or ingestion of faeces containing the BVD virus. Other possible routes of transmission are 

semen, milk, saliva, urine, placenta and birth fluid. It is also possible for the BVD virus to be 

spread through cattle yards, stock trucks and to be carried around on footwear. The virus 

can survive in the environment for up to seven days. Once contact has taken place the 

virus replicates inside the epithelial cells and spreads as a free virus within infected blood 

cells, penetrating different tissues in the body. 

5.3.1 Persistently Infected (PI) animals 

As the name suggests, a PI animal is one that continually sheds the BVD virus throughout 

its life. Some PI animals can be recognised by vets and farmers as ‘poor doers’. These 

animals often succumb at a relatively young age from a more severe form of BVD called 

Mucosal Disease, or other diseases associated with BVD, e.g. pneumonia. It is estimated 


77 

that about half of all PI cattle die within the first 12 months of life and 80% are dead by two 

years due to the virus causing suppression of the immune system,. However, some PI 

animals appear normal, survive longer than 18 months and act as long term carriers of BVD 

virus, continuing to infect those naïve animals in the herd not yet exposed. These PI 

animals do not show obvious signs of illness and are difficult to recognise. They can breed 

successfully but their progeny are always PI, thus perpetuating the disease in the herd. 

Surviving PIs make up about 1% of the adult cattle population. 

In dairy herds, calves – including PIs – are removed from their mothers, only to return to the 

milking herd a couple of years later. This leads to a regular cycle of re-infection every few 

years. However, in suckler beef herds, calves and cows are kept together allowing a much 

more dynamic spreading of the disease, back and forth between younger and older 

animals. This means that PIs can be in constant contact with susceptible new calves, 

replacements, bulls and the breeding herd. 

5.3.2 How does the virus affect cattle? 

Calves may be sub-clinically affected and not show symptoms except perhaps reduced 

liveweight gain. Other calves (3-12 months age) can show a range of symptoms including: 

Reduced appetite 

Nil or poor liveweight gain 

Scouring 

A rough coat and a loss of body condition 

Coughing 

Discharge from the eyes and nose 

Ulcers in the mouth and between the toes 

Premature death of PI animals 

BVD is often characterised by high morbidity but low mortality. BVD in young stock is 

frequently not diagnosed or miss-diagnosed because symptoms can be similar to 

parasitism. Some farmers therefore mistakenly drench without getting a diagnosis. Since 

most stock recover after a BVD infection, farmers often get the false impression that their 

stock have responded to the parasite drench. 


78 

Reproductive wastage occurs when a heifer or cow becomes exposed to BVD virus for the 

first time when it is pregnant. The outcome depends on when the pregnant cow is infected 

after conception: 

0-45 days 

Cow fails to conceive or loses embryo and returns to service (long returns) 

45-125 days 

Virus causes an abortion and return to service, or results in the birth of a PI 

animal which may be sick, scouring, stunted or apparently normal 

125-180 days 

Virus enters the unborn calf, producing a variety of effects including abortion 

and congenital deformities. 

Introducing PI bulls to a herd during mating, especially a naïve herd, can be devastating 

and very expensive. PI bulls are the biggest cause of introduced BVD infection in to a herd 

and are a significant threat to the reproductive performance of beef breeding herds 

PI breeding bulls affect reproductive performance through direct, horizontal spread of the 

virus to BVD-free and heifers during breeding or pregnancy. Cows may be infected by 

transmission of the virus directly into the reproductive tract during mating, which can affect 

conception and fertility of the dam being bred; and through poor semen quality. 

5.3.3 Control of BVD 

To control the disease all breeding bulls should be blood tested prior to mating and certified 

as BVD virus antigen negative and then vaccinated twice, three to four weeks apart, and 

prior to mating. Vaccination will protect them from acquiring a transient infection from a PI 

cow, heifer or calf with which they are going to be joined which could cause temporary 

infertility. Previously vaccinated bulls require an ongoing annual booster prior to each 

mating. 

Herd control options include eradication by blood testing all the herd (cows, calves, heifers, 

steers, bulls), identifying the PIs and culling them. Then either adopt stringent biosecurity 

measures that will prevent the herd getting re-infected or protect animals through 

vaccination. In New Zealand, with large numbers of livestock, large farms, often many 

neighbouring farms with livestock, lack of stock proof fences, frequent livestock movements 


79 

off and on the farm, purchase of stock with unknown BVD status, biosecurity is often not 

applicable or manageable. This leaves vaccination as the only practical option. 

To reduce costs, some farmers elect to vaccinate without blood testing and eradication. 

This way all BVD-free cows will be protected and any PIs in the herd will eventually die or 

be sold. Over time, the herd should become BVD free. With the high incidence of BVD in 

herds in New Zealand, a lot of older cows will be naturally protected, so a practical way to 

start off is to vaccinate the heifers in the first year then follow them up with annual booster 

vaccinations annually. Keep vaccinating the new crop of heifers each year, until eventually 

the whole herd is vaccinated and protected. 

5.4 Nitrate poisoning 

High levels of nitrate and nitrite in plants and water sources are the primary cause of acute 

nitrate poisoning in cattle. Plants which are the main source of nitrates for cattle (and 

poisoning) include regrowth rape, choumollier, turnips, immature green oats, Italian rye 

grass and young maize. Nitrate poisoning is rare on permanent pasture. Rapidly growing 

plants, grown in nitrogen rich soils, after a period of drought, are most dangerous. 

Nitrate poisoning in cattle is due to either ingestion of pre-formed nitrite, or to the conversion 

of nitrate to nitrite in the rumen by micro-organisms. Severe loses can occur as a result of 

sudden deaths, and abortions, in cattle consuming high levels of nitrate in their diet. 

Treatment is with methylene blue administered intravenously. 

Beef cows grazing regrowth crops or fresh herbage after a drought are especially 

susceptible to high nitrate intake. Plants can be tested. A good handful of plant materials, 

including the stalk, should be sent to an animal health laboratory. 

5.5 Bloat 

5.5.1 Overveiw 

Bloat is not a common problem for beef cattle, but when it occurs, it can be very difficult to 

manage. Its occurrence can be sporadic and hard to predict. Animals vary, genetically, in 

their susceptibility to the problem and resistance is quite highly inherited. Bloat occurs 

when stable protein foam develops in the animal’s rumen and cannot be belched out like 

the normal rumen gases, which are constantly produced. The end result can be fatal, 


80 

because of physical pressure on internal organs such as the heart, which eventually stops. 

Bloat is most prevalent in early spring and where soil fertility and pasture quality are high. It 

is more common, but not exclusively so, on pastures of high clover content. Bloat can also 

occur on brassica crops and the new fast-growing grasses. Low fibre content seems to be 

a factor. 

In all bloat risk situations, adding fibre such as hay to the diet decreases the risk. When the 

risk is very high, adding anti-bloating agents to water either in the water supply or as a 

drench can be very effective, but the latter process is very tedious and impracticable in run 

cattle. Slow-release, Rumensin “bullets” are effective and are also reported to give a 

liveweight gain response. 

5.5.2 Management measures to reduce the risk of bloat 

Ensure the animals are not hungry when they are introduced to dangerous pasture 

Likewise, do not use strip grazing (behind a hot wire) on dangerous pasture. Strip 

grazing creates the “hunger/eat ravenously” cycle 

Provide fibrous feed, such as hay, as a supplement with dangerous clover pasture 

to increase chewing time and rumen fill and reduce bloat risk. 

If planting new pasture, use a balance of grasses and clover in the seed mix. 

Plants with high tannin content (e.g. docks) reduce bloat risk. 


BVD website: www.controlBVD.org.nz. Established to help farmers and other interested 

parties deal with BVD issues. 

Heuer, C.; Tattersfield, G.; West, D.M.; Olson, W.O. 2008. Effect of reproductive 

pathogens on pregnancy rates in beef herds. Proceedings of the 38th Seminar of 

the Society of Sheep and Beef Cattle Veterinarians NZVA, May 2008, pp 141-147. 

Facial eczema spore counting: Appendices III and IV. In Profitable beef production, A 

guide to beef production in New Zealand. A book, published by Meat & Wool 

New Zealand, Beef Council. Third Edition. Meat & Wool New Zealand, PO Box 121, 

Wellington. 

Coddington, N. 2008. Cattle animal health, Ch 7 In Profitable beef production, A guide to 

beef production in New Zealand. A book, published by Meat & Wool New Zealand, 

Beef Council, Third Edition. Meat & Wool New Zealand, PO Box 121, Wellington. 


Summary 

81 

Chapter 6: Genetics of calf production from beef cows 

Most of the beef cattle in New Zealand are managed in commercial herds, with bulls 

purchased from outside the herd. Little or no individual recording is undertaken. A small 

proportion of cattle are located in registered herds where pedigree recording with breed 

societies has been mandatory. These herds produce almost all of the bulls used in 

commercial herds. There is a time lag before genetic benefits generated in the nucleus 

(seedstock) herds are expressed in the commercial herds. 

To be included in a genetic improvement programme a selection trait must be: 

(1) economically important, (2) measurable, (3) heritable and (4) characterised by variability 

in the population. The higher the heritability of a trait, the greater the proportion of the 

parental genetic merit passed on to the offspring. Most of the growth traits in beef cattle 

have a heritability of between 30% and 50%. The other 50-70% of the measured 

differences in performance (e.g. growth rate) between animals in a group, are due to 

environmental factors. 

The first step in the development of a breeding objective is to identify the goal; typically this 

is profit oriented. Then, define a list of traits that influence the goal and to which economic 

values for unit changes can be attributed. In order to construct a single index value 

encompassing several selection traits, economic values are needed for each relevant trait. 

‘BREEDPLAN’ is a breeding programme widely used in beef recording in New Zealand and 

Australia. It estimates the genetic merit, or breeding value of an animal from a number of 

measurements made at various stages of the animal's life and from the performance of its 

relatives. It reports estimates of genetic merit as Estimated Breeding Values (EBVs) for 

each trait. EBVs are expressed as positive or negative deviations from a base which is set 

at zero on a fixed date. The reliability of EBV estimates indicates the likelihood they will 

change with the addition of more information over time. EBVs are a very powerful tool to 

improve profitability. 

‘BREEDPLAN’ also administers ‘BreedObject®’ (the Index System). It has a number of 

advantages over EBVs. It uses a measure of profit per cow mated to genetically rank 

animals and avoids the problem of trying to select animals based on an array of EBVs for 

Profitable Farming of Beef Cows Chapter 6: Genetics of calf production from beef cows

82 

different production attributes. BreedObject deals with all the difficult mathematical 

calculations involved in making a genetic decision. 

Growth rate is in most cases the primary selection criterion for beef cattle breeders because 

it is easy to measure and is related to efficiency or economy of production. However, 

breeders that select solely for growth rate need to be aware of correlated responses such 

as increased mature cow weight resulting in increased feed intakes and increased birth 

weight and calving difficulty. 

The choice of breed for a particular farm will often involve compromises. Advantages of 

different breeds can be attained by using sires with different attributes from dams, e.g. 

Simmental bull mated to a Hereford x Friesian cow. 

Crossbreeding is an established breeding method used in sheep and beef cattle breeding to 

increase overall productivity through hybrid rigour. The challenge is to identify appropriate 

crossbreeding systems that are simple and easy to operate in commercial beef breeding 

cow herds. The use of composite breeds where 3, 4, 5 and up to 8 breeds have been 

interbred to form a new breed is also a possibility. 


Most of the beef cattle in New Zealand are managed in commercial herds with bulls 

purchased from outside the herd. Little or no individual recording is undertaken. A small 

proportion of cattle are located in registered herds where pedigree recording with breed 

societies has been mandatory. These herds produce almost all of the bulls used in 

commercial herds. Industry genetic change is dictated by the direction and rate of progress 

achieved in the registered herds. 

The number of new bulls required each year by the beef industry can be estimated by 

considering the total beef cow and heifers in-calf (1,195,000 in 2008/09), the number of 

cows or heifers mated by each bull (say 1 bull to 50 cows) and the average working life of a 

bull (say 3 years). These figures suggest a total requirement of around 23,900 bulls and an 

annual requirement of 8,000 bulls. 

The way in which cows are split between bull-breeding registered and recorded herds and 

commercial cow herds is often represented as a triangle (Figure 6.1). The bull breeding 


83 

herds (sometimes referred to as seedstock breeders) are at the top of the triangle and 

commercial herds are at the base of the triangle where the majority of the cows are found. 

Figure 6.1: Diagrammatic representation of bull breeding herds and commercial herds 

in New Zealand. 

When genetic gains are generated in the nucleus (seedstock) herds, there is a time lag 

before these genetic benefits are expressed in the commercial herds. 

When a commercial farmer consistently buys bulls from a nucleus (or seedstock) breeder, 

the commercial farmer's herd will, within the next 2-3 generations (10-15 years), be at the 

same genetic level as the nucleus herd was when the bulls were bought. This 2-3 

generation delay is called genetic lag. In the meantime, the breeder’s herd will have 

continued to improve (Compare Client vs. Breeder A in Figure 6.2). This highlights the 

importance of choosing the right nucleus breeder to buy bulls from. The most important 

single factor in making that choice is that the breeder's herd must a have higher genetic 

merit and rate of improvement than the commercial herd. 

Figure 6.2 shows that the client who purchases bulls from Breeder A will progress at a 

similar rate to Breeder A, although 2 generations behind. If bull breeder B or C were 

chosen much less progress would be made. 

The two generation lag can be reduced by purchasing, year after year, bulls at a level 

above the average of Breeder A's bulls but the genetic gain in the commercial herd cannot 

exceed that of the nucleus herd. It is likely that the above average genetic merit bulls will 

also cost more, requiring the commercial producer to undertake a cost benefit analysis to 

examine whether the reduced lag justifies the additional expense. 


Figure 6.2: Genetic lag between commercial and bull breeding herds 

84 

An alternative to purchasing high genetic merit animals from bull breeders is to use 

reproductive technologies such as artificial insemination (AI), multiple ovulation and embryo 

transfer (MOET), and in vitro embryo production and embryo transfer. Using these 

techniques, the commercial breeder can access high value bulls (through AI) or high 

genetic merit cows (through MOET). In theory the genetic lag could be reduced to about 

5 years through use of AI, since only the genetic merit of the cows will lag behind the 

nucleus. These technologies are not in common practice in the New Zealand beef industry 

at present and are more likely to be used by breeders than commercial herds. 

6.1.1 Selection decisions 

Nucleus (seedstock) herds need to: 

1. establish selection objectives and 

2. generate genetic gains in objective traits 

Commercial herds need to: 

1. establish selection objectives 

2. choose a breed mix 

3. choose a seedstock breeder with the same objective 

4. choose bulls consistent with objectives 

5. choose heifer replacements in accordance with objective and 

6. minimise the genetic lag behind the seedstock breeder 


85 

To be included in a genetic improvement programme a selection trait must meet four basic 

criteria: (1) be economically important, (2) measurable, (3) heritable and (4) characterised 

by variability in the population. Economic importance can mean different things to different 

producers. For example a farmer selling weaners at 7 months of age will have slightly 

different economic criteria to a farmer who breeds cattle and carries all progeny through to 

slaughter. Objective measurement of beef cattle performance traits enables the breeder to 

compare the traits irrespective of season, bias, year or environmental effects, and allows 

the calculation of estimates of genetic merit. Liveweight is easy to measure and is a logical 

first choice for most of the genetic improvement programmes. 

Heritability is an important term. It is defined as that proportion of the difference in 

performance between individuals that on average is passed on to their offspring. So if the 

heritability of a trait is high we can expect that much of the difference in performance of 

parents will be passed on to their offspring. Conversely if the heritability is low only a small 

percentage of this difference will be transferred. Heritabilities are expressed as proportions 

(from 0 to 1) or percentages (from 0 to 100). 

The higher the heritability of a trait, the greater the proportion of the parental genetic merit 

passed on to the offspring. Most of the growth traits in beef cattle have a heritability of 

between 30% and 50%. This means that of the measured differences in growth rate 

between animals in a group, 30-50% are due to genetic factors and 50-70% to non-genetic 

or environmental factors. Carcass traits generally have heritabilities of between 30% and 

55%. Female fertility traits tend to have much lower heritabilities of between 5% and 20%. 

This means that a smaller proportion of the measured differences between animals for 

fertility are due to genetic differences, and so the rate of improvement in fertility traits in a 

genetic improvement programme will be slower than for the other traits. Heritability 

estimates for some of the important traits of beef cattle are shown in Table 6.1. Traits that 

have greater variation, have more scope for change. Some traits vary more than others 

and even if a trait has a low heritability, a large variation may mean that significant changes 

can be made. 


86 

Table 6.1: Heritability estimates for some traits in beef cattle in temperate and tropical 

environments Source: Adapted from Anon (2000) Note AA = Angus breed, BR = Brahman 

breed, na = data not available. 

Trait Heritability 

Description 

Heritability estimate (%) 

Temperate 

(AA) 

Tropical 

(BR) 

Reproduction 

Conception low 0-5 5-20 

days-to-calving low 0-10 0-10 

calving ease (heifers) low-medium 15-50 na 

semen quality low-medium 25-40 6-44 

scrotal circumference (18 months) medium-high 20-50 28-36 

serving capacity (18 months) low-high 15-60 na 

maternal ability medium 20-40 na 

gestation length 

Conformation and growth 

medium 15-25 21 

birthweight medium 35-45 35-45 

milk yield medium 20-25 4 

weaning weight medium 20-30 3-50 

200-day weight medium 18 28 



mature cow weight 

Carcass 

high 50-70 25-40 

carcass weight/day of age medium 25-45 36 

rib fat (12/13 th rib) medium 27 27 

P8 rump fat medium-high 29 18 

Intramuscular fat (IMF%) medium-high 15 30 

eye muscle area (EMA) medium 20-25 23 

dressing % medium-high 15 37 

tenderness high 4-25 16-30 

retail beef yield (RBY%) high 29 36 

yield % carcass weight 

Other traits 

high 49 52 

temperament medium-high 25-50 25-50 

worm resistance medium na 25-36 


6.2 Selection objectives 

87 

Selection or breeding objectives play an important role in the design of improved animal 

breeding programmes as well as assisting with selection decisions involving a number of 

genetic traits. In addition, breeding objectives are having an increasingly important role in 

determining the acceptance and adoption of modern animal breeding technologies. Given 

that the adoption of these technologies has been much greater in non-ruminants such as 

pigs and poultry than it has been in some ruminants such as beef cattle, this latter point is of 

considerable importance. 

6.2.1 Breeding objectives 

The first step in the development of a breeding objective is to identify the goal (e.g. superior 

400 day weight). A breeding objective will reflect the production and economic objectives of 

the individual. The exception could be the bull breeder who may have a number of 

objectives reflecting their own and their various clients’ objectives. 

Given a clearly defined goal, the next step in the development of a breeding objective is to 

identify traits that influence the goal and to which economic values for unit changes can be 

attributed. A diagram of some possible economically-relevant traits is shown in Figure 6.3. 

For a given situation, there may be alternative objective trait lists with different traits and 

different definitions. Clear and precise definition of traits is very important. Correlations 

between traits also need to be considered. For example, selection for yearling weight can 

increase birth weight and in some cases increased calving difficulty. Selection on birth 

weight can be used to limit correlated increases in calving difficulty. Highly sought after 

bulls have low birth weight and high yearling weight breeding values. 

Figure 6.3: Some factors influencing profitability in beef cattle 


6.2.2 Economic weights and values 

88 

In order to construct a single index value encompassing several selection traits, economic 

values are needed for each relevant trait. Economic values should be defined as the net 

benefit from improvement in an individual breeding trait in absolute ($ value) terms. This 

value is expressed per unit change holding all other breeding objective traits constant. This 

helps avoid the potential for double counting of benefits. 

In many instances, "economic value" and "economic weight" are terms used 

interchangeably. However, it is helpful to give economic weight a different definition. We 

define here the economic weight as the benefit of improvement in an individual breeding 

objective trait, expressed relative to some other trait of interest. 

6.2.3 The importance of future prices 

Many breeders are comfortable with the concept of profit (from the commercial farm 

viewpoint) as the appropriate goal for a breeding programme. The question is, how does 

one ensure that a comprehensive list of traits that influence profit is identified, and that the 

economic values are appropriate? 

Profit = income – feed costs – non-feed costs 

Inspection of the above equation allows one to systematically break down the components 

of income, feed costs and non-feed costs relevant to a particular farming circumstance. 

However, there is a danger with this approach that one can focus on the economic and 

management circumstances relevant to the current year, giving undue attention to present 

rather than future determinants of income, feed and non-feed costs. 

Consider the process of selection and mating that will occur in bull breeding herds in year 1. 

The offspring will be born in the spring of year 2, with bull calves, sold as rising two-year 

olds, for mating in year 4. These bulls will join with commercial cows in the spring of year 4 

producing calves in the spring of year 5. If the farmer sells weaners, the first impact the 

original bull breeding has on income will be in the autumn of year 6. If the farmer finishes 

the male and surplus female offspring, this crop will be typically harvested in late year 6 or 

in year 7. Bulls used for 4 breeding seasons will continue producing terminal offspring until 

year 10. Where daughters are retained for breeding, they will have their first calves, if 

mated as yearlings, in year 7. Cows may remain in the herd for 7 or 8 calvings, or until year 

17 if the bull is used as a sire for 4 years. So, the impact of selection decisions in 


89 

bull-breeding herds in year 1 will affect the commercial farmers’ income from year 6 until 

year 17. It is therefore future circumstances that are important, not today's. 

Breeders must consider the determinants of income, feed costs and non-feed costs in a 

time-frame that extends at least 10 years beyond today. Yet information on these 

determinants will not be known with certainty by the breeder in year 1. Still these issues 

must be considered and debated by breeders and farmers if they are to make informed 

decisions as to their breeding objectives. 

6.2.4 Selection criteria 

Having established the selection (breeding) objective, the next step is to decide which 

animals and which characteristics are going to be measured to help in predicting the traits 

included in the objective. These characters are referred to as selection criteria. 

Selection criteria can be defined as a subset of the characteristics of animals which can be 

evaluated or measured and will form the basis of the criteria used to estimate the value of 

breeding animals. Selection criteria can be many and confusing! For example, the 

following factors may influence a commercial farmer’s decision to purchase a bull. 

Price - can vary according to external factors 

Breed 

Appearance - e.g. coat colour, horns, conformation 

Structural soundness - feet, legs, shoulders, jaw 

Individual performance - weight of bull on sale day or weight gain up to sale day 

Pedigree - sire and dam information 

Genetic merit of bull - estimated breeding values (EBVs) 

As was mentioned in the section on selection objectives, it is common for breeders to be 

interested in improving several traits simultaneously. There are three methods of selecting 

for multiple traits. 

Tandem selection: This involves ranking animals for the most important trait and culling 

on that trait. At some point in time, selection is relaxed on the first trait and imposed on a 

second trait instead. Over time, selection proceeds through the list of traits in tandem. This 

form of selection is the least effective as it is difficult to decide when to change from one 

trait to the next, and if there are several traits, which is common in beef cattle production, it 


90 

will take considerable time before selection can be imposed on all traits. Another difficulty is 

when two or more traits are unfavourably genetically correlated. In this case selection for 

an increase in one trait will result in a correlated decrease in a second trait. On changing 

selection from the first to second trait, there could be a related decrease in the first trait, 

undoing some of the selection response achieved. 

Independent culling levels: Selection using independent culling levels involves ranking 

the animals for each trait in the selection objective. For each trait, some of the inferior 

animals are culled. The relative importance of each trait will determine the extent to which 

selection is imposed on that trait. Independent culling is widely used for culling animals on 

conformation traits. For example heifers which have unacceptable feet or black Angus 

cattle with white markings are likely to be culled regardless of their genetic merit for other 

traits of interest. 

Selection index: The selection index method to combines information from a number of 

traits with known economic values so that animals can be compared. The selection index 

method has not been used widely in the New Zealand Beef Industry, but is common in the 

sheep and dairy industry. A new tool available through BREEDPLAN called BreedObject is 

a selection index now available for New Zealand breeders. 

6.3 Estimated Breeding Values (EBVs) 

‘BREEDPLAN’ is a widely used breeding programme which estimates the genetic merit, or 

breeding value of an animal using a number of measurements made at various stages of 

the animal's life and the performance of its relatives. BREEDPLAN reports estimates of 

genetic merit as Estimated Breeding Values (EBVs) for each trait. EBVs are predictions of 

relative genetic merit, (what they will pass on to their progeny) not measures of the 

observed differences between animals. EBVs are expressed as positive or negative 

deviations from a base which is set at zero on a fixed date. 

EBVs are reported in the unit of original measurement, for example growth traits in 

kilograms (kg), scrotal size in centimetres (cm) and days-to-calving (days); they are 

expressed as deviations from a base average, which is set from a particular year for each 

EBV. 


91 

Group BREEDPLAN allows across-herd genetic evaluation of cattle from herds which are 

linked genetically and have been recorded with BREEDPLAN. EBVs are available for 

growth, carcass, reproduction and other traits. 

6.3.1 Growth EBVs 

1. Birth Weight EBV: If recorded, the weight should ideally be taken immediately or 

at least within a few days of birth. Birth weight is associated with an animal's weight 

at later ages: in general, calves which are heavier at birth tend to be heavier later in 

their life. An EBV for birth weight is not available unless the calf's birth weight or 

that of a number of its relatives has been measured, although it may be estimated 

with reduced accuracy from later weights such as weaning weight. Buyers looking 

for easy calving bulls can use birth weight EBV as a guide, but should look carefully 

at the accuracy of the EBV. 

2. 200-day growth and 200-day milk EBVs: These EBVs are derived from the 

records of calves weighed between 81 and 300 days of age. The 200-day weight 

(the measure of pre-weaning gain) is derived or influenced from three sources: 

the calf's inherent growth potential 

the dam's merit for milk production and milk quality 

performance of all known relatives e.g. sire, dam, brothers and sisters. 

The 200-day growth and milk EBVs are calculated for the 'growth' and 'milk' genes. 

Note that the milk estimate in kilograms is not the yield of milk of the dam, but the 

growth rate in the calf attributable to the dam’s milking ability. It is an indirect 

measure of the milk production of the dam expressed in kilograms of calf weight at 

200 days. It should be used in the selection process, if the contribution of the dam 

through her milking ability, is important in a particular production system. 

Each time a 200-day weight is recorded it increases the reliability of the EBVs for 

growth and milk of all relatives of the particular calf. An EBV for milk in a calf is 

simply a calculation of the average of its sire and dam's EBV for milk and is called a 

mid-parent value or average. It is not until females have progeny, and males have 

daughters that have weaned calves, that the EBVs for milk will change from the 

average of their parents' EBVs. 


92 

The heritability of 200-day milk is about 8%, which means that genetic progress in 

this trait will be slow. Conversely, the heritability for 200-day growth is about 20%, 

which enables greater opportunities in improved growth following selection using 

this trait. Since EBVs for milk are less heritable than growth EBVs, they are more 

likely to fluctuate as new information is added relative to growth. 

3. 400-day yearling weight EBV: This EBV covers records of calves weighed 

between 301 and 500 days of age. This EBV is most useful for selection in yearling 

production systems in which cattle are sold some months after weaning. 

4. 600-day final weight EBV: Final weight EBVs are computed for growth and 

recorded between 501 and 900 days of age. It is an estimation of an animal's ability 

to continue to grow to an older age. 

5. Mature cow weight: This is defined as the cow's weight recorded at the same time 

as her calf is weaned. The mature cow weight EBVs are estimates of the genetic 

differences in weights between cows at weaning during production of their first four 

calves. Mature cow weight EBVs for sires are based on weights recorded from their 

daughters (following weaning of their calves) plus the correlations that exist between 

cow weight and earlier growth performance. Mature cow weight EBV values can be 

used to influence the mature size of the females in the herd. 

6.3.2 Reproduction EBVs 

1. Scrotal size EBV: This is adjusted to 400 days. An animal with a greater scrotal 

size EBV will produce male progeny with relatively larger scrotal circumferences and 

daughters that reach puberty at an earlier age. The sons of bulls with larger scrotal 

size will on average have greater daily and total sperm production, which can be 

associated with increased fertility. There is also a negative relationship between 

scrotal size and days-to-calving of the female progeny, i.e. daughters will have 

fewer days to calving. 

2. Days to calving: This EBV is an estimate of the genetic differences between cows 

in fertility, expressed as the number of days for the period from when the bull is 

placed with the females to calving. A female with a shorter days-to-calving EBV 

tends to reach puberty earlier as a heifer, return to oestrus earlier after calving and 

conceive early in the joining period. A lower days-to-calving EBV value indicates 

greater opportunity for the cow to conceive within any one mating period. Cows that 


93 

do not calve are given a 'penalty' figure. These EBV values for bulls are based on 

the performance of their daughters and female relatives. 

3. Gestation length EBVs: These are estimates of genetic differences between 

animals in the number of days from the date of conception to the calf birth date. 

Gestation length EBVs are expressed in days. Gestation length is available only 

when the conception date is known, that is, in the case of artificial insemination. 

Gestation length is one component of days-to-calving. An animal with a more 

negative EBV will have progeny with a shorter pregnancy, more time to get back in 

calf relative to females with a larger EBV, and potentially a smaller calf. 

4. Calving ease: This EBV indicates the degree of difficulty experienced by the dam 

at birth. The direct calving ease EBV is an indication of that animal's ability to calve 

easily. Its components include gestation length and birth weight. Calving ease 

maternal is the EBV associated with the daughter's ability to calve. A larger positive 

value for both direct and maternal calving ease EBV, is a desirable selection option. 

Birth weight EBV is a commonly used proxy for calving ease because it is a more 

available statistic. However, it does not predict calving ease as accurately as 

calving ease EBV. 

6.3.3 Carcass EBVs 

Five carcass EBVs are available based on live animal ultrasound scan measurements taken 

by accredited scanners and information collected from actual carcass data. The measures 

are eye muscle area, rump fat depth, rib fat depth, intramuscular fat % (IMF%) and retail 

beef yield % (RBY%). Extra data collected at abattoirs, (including hot carcass weight, 

marble score, meat colour, fat colour and meat pH) can be stored on the database. The 

quality EBVs are expressed in terms of a 300 kg dressed steer carcass weight and 

measured between 300 and 800 days of age with a preference for measuring at less than 

two years old. 

1. Carcass weight: These EBVs are estimates of the genetic differences between 

animals' untrimmed hot carcass weight at 650 days of age and are based on 

slaughter carcass weight records. 


94 

2. Fat depth: This can be readily measured at the 12/13th rib site and the P8 rump 

site on a standard 300 kg carcass. The measurement at the 12/13th rib has a 

genetic correlation of 0.9 with P8 fat and is utilised in the multi-trait model to refine 

the EBV for P8 fat. Fat depth has a negative relationship with retail beef yield. 

3. Eye muscle area (EMA): This is measured in cm 2 at the 12/13th rib on a standard 

300 kg carcass. Eye muscle area and fat measurement are used in the prediction 

of retail beef yield % from a live animal or carcass. Larger eye muscle area EBVs 

are associated with higher carcass yield and often with leaner carcasses. 

4. Retail beef yield (RBY %): The major reason for measuring either fat depth or eye 

muscle area is to predict the yield of meat from the live animal or carcass. 

Equations have been developed for the within-breed calculations of retail beef yield 

percentage. These include age, liveweight, fat depth and eye muscle area with fat 

depth having a greater influence than eye muscle area. Retail beef yield % EBVs 

can be used to select for yield of retail cuts for carcasses. 

5. Intra-muscular fat (IMF %): This is a measurement of the percentage of fat within 

the 'eye muscle' and is similar to 'marbling score' as reported at slaughter. 'Marbling 

score' is a subjective assessment of intramuscular fat. IMF% is based on a 300 kg 

standard carcass. IMF% EBVs are important in the selection of sires to produce 

progeny for markets that require increased amounts of marbling in carcasses (e.g. 

Japan). 

6.3.4 Additional EBVs available 

1. Feed efficiency: Net feed intake EBVs can be used to predict the differences in 

feed consumption among progeny of different sires adjusted for differences in their 

growth performance. Net feed intake is sometimes referred to as residual feed 

intake (RFI), net feed efficiency (NFE) or net feed conversion efficiency (NFCE). A 

negative net feed intake EBV is preferred. Recording for this EBV is expensive and 

is available in Australia but not yet New Zealand. 

2. Other traits: A number of traits are being analysed according to demand. This 

varies between the breed societies that use BREEDPLAN. Traits available for 

analysis may include: animal length records (e.g. hip height), conformation records 

(e.g. leg score), temperament records (e.g. flight speed) and parasite records (e.g. 

tick score). 


6.3.5 Accuracy of EBVs 

95 

There are benefits in knowing the reliability of EBV estimates and the likelihood they will 

change with the addition of more performance information about the animal or its relatives. 

Accuracy is expressed as a % and is calculated from the number of performance records 

that are available for each trait on the animal itself, as well as its progeny and relations 

(Table 6.2). The higher the accuracy, the greater the confidence that the EBV is an 

accurate estimate of the animals’ true breeding value, and the less chance of it changing as 

more information becomes available. 

An accuracy of less than 55% indicates that no direct information is available about the 

animal. Information may come from relatives rather than direct observation or from a 

correlated trait. An EBV with this level of accuracy should be considered a preliminary 

estimate only and could change considerably up or down as more substantial information 

becomes available. 

Table 6.2: Accuracy values for a trait (assumed heritability 30%) when additional 

performance records are added to an EBV. 

Performance measured on: Accuracy (%) 

Individual 55 

Individual + 10 PHS* + 2 MHS 

Profitable Farming of Beef Cows Chapter 6: Genetics of calf production from beef cows 

61 

Individual + 20 PHS + 4 MHS 64 

10 progeny 67 

32 progeny 85 

55 progeny 90 

Individual + 10 progeny 74 



* PHS: paternal half sibs or other calves by the same sire, MHS: maternal half sibs or other 

calves by the same dam. 

EBVs for yearling bulls without progeny recorded are calculated from the record of the bull 

and/or its relatives. The accuracy of these EBVs will be in the range of 40% to 75%, with 

the higher accuracy EBVs reflecting greater information from relatives. The EBVs of sires 

with recorded progeny are more accurate and more stable than the EBVs of bulls without

96 

progeny. Progeny information is a better estimate of a bull's breeding value than the 

individual's performance. These EBVs will range in accuracy from 75% to 99%, with the 

higher accuracy EBVs reflecting a greater number of progeny and/or the availability of 

daughters' progeny records. 

6.3.6 Profitable use of EBVs 

EBVs are a very powerful tool in selecting animals to improve profitability for both breeders 

and commercial buyers. For example, the progeny of bulls in the top 1% of the Angus 

breed for carcass weight generate 17.5 kg more carcass weight at 22 months of age than 

bulls in the bottom 1% (1999 NZ Angus Genetic Evaluation Report). This demonstrates an 

important aspect of EBVs. That is, the more highly ranked the animal is in the breed, the 

greater the genetic progress and the more profit the bull will generate. Therefore a buyer 

can afford to pay more for highly ranked bulls. Percentile bands show where a particular 

animal ranks within a breed for a specific trait. 

Different types of animals are needed to fit the various performance levels of existing herds 

and suit the range of market requirements in the beef industry. EBVs from BREEDPLAN 

can be used to select or buy bulls to improve different systems. For example, growth 

figures for five bulls are shown in Table 6.3. 

Table 6.3: EBVs Group BREEDPLAN (kg) for several growth traits for five bulls. 

Sire 

Birth 

Weight 

200-day 

milk 

200-day 

growth 

Yearling 

weight 

Final 

Weight 

1 -1 +5 +10 +30 +45 

2 +2 +2 +14 +25 +28 

3 +5 -8 +16 +40 +50 

4 +2 +10 +10 +25 +30 

5 +1 +2 +10 +28 +40 


97 

Selection of a sire will depend on what production system the farmer operates as 

demonstrated in the examples below. 

Buyer 1 sells weaners and does not retain any heifers, choosing to buy in replacement 

females. The breeder places most emphasis on EBV for weaning weight, while trying to 

avoid large birth weights. The most likely choice is Sire 2 (sire 3 is rejected because of +5 

for birthweight). 

Buyer 2 sells weaners but also breeds their own replacement heifers. The breeder thinks 

that increasing the level of milk production in the herd would be profitable. Sire 4 is the 

most likely choice because of its emphasis on milk and early growth rate. 

Buyer 3 wants to increase yearling and final weights, avoid calving difficulty and slightly 

increase milk production. The main product is steers to finished weights and the breeder 

retains replacement heifers. The most likely choice would be Sire 1. 

Buyer 4 breeds straight-bred animals in a harsh environment where cows with high EBVs 

for milk are known to be slower to rebreed. The breeder wants to maintain the current 

levels of birth weight and milk production while increasing growth rate in two year old cattle. 

The most likely choice would be Sire 5. 

6.4 Index Selection (BreedObject) 

BreedObject® (the Index System) is also administered by BREEDPLAN and has a number 

of advantages over EBVs. Any worthwhile genetic selection programme should target profit 

as its goal, however most EBVs are only indicators of potential to make profit and do not 

directly influence it. For example, you do not get paid directly for the milking ability of a beef 

cow (200 Milk EBV), however it does contribute to the survivability and growth of the calf. 

BreedObject uses a measure of profit per cow mated to genetically rank animals. The 

presence of so many EBVs makes the selection process very confusing because buyers 

often do not know which EBVs to target or how to financially prioritise them. Also, buyers 

cannot account for the impact of genetic correlations (relationships) existing between traits. 

BreedObject ranks the bulls using easily understood and meaningful criteria, i.e. dollars per 

cow mated, and presents just one genetic selection figure – EBV for profit as the index 

measure. 


6.4.1 Angus BreedObject 

98 

The Angus breed for example has three BreedObject indices: the Self-Replacing Index, the 

Ease of Calving Index and the AngusPure Index. 

1. The New Zealand Angus Self Replacing Index 

The Angus Self-Replacing Index ranks bulls on their progeny’s ability to generate profit 

(profit per cow mated) in a self-replacing herd situation in which some females are 

retained for breeding and surplus females, along with all males, are slaughtered. The 

main drivers of profit included in the Index (in order of economic importance) are: 

Direct and Maternal Calving Ease 

Growth 

Meat Yield 

Cow Survival 

Finishing Ability 

Fertility 

Cow Efficiency 

In short, selection on this Index is expected to favour production of a cow herd with 

excellent reproductive efficiency, rearing progeny with moderate-to-high growth rates 

and high yielding carcasses. 

2. The New Zealand Angus Ease-of-Calving Index 

The Angus Ease-of-Calving Index ranks bulls on their progeny’s ability to generate profit 

(profit per cow mated) when crossed with dairy cows and heifers to produce dairy beef 

progeny. While calving ease is by far the most important profit driver in the Index, 

growth and to a lesser extent meat yield also contribute. This Index is also a reasonable 

indicator of a bull’s suitability for use over beef heifers. 

3. The AngusPure Index 

The beef production system that this index targets is the same as for the self replacing 

index but has a greater emphasis on higher marbling sires with progeny sale at around 

16-17 months of age. 


6.4.2 Hereford BreedObject 

There are three breed-specific selection indexes for Hereford cattle: 

99 

1. Export/Maternal Index – This focuses on the production of a 555 kg steer by age 

20 months from a self replacing cow herd (that is, a herd producing females over a 

5 year period to continue the breeding policy). 

2. Hereford Prime/Maternal Index – This focuses on producing a 510 kg steer by age 

18 months. 

3. Dairy/Maternal Index – This aims to produce readily marketable crossbred steers 

at 475 kg by 16 months, but is also useful for people breeding Hereford x Friesian 

cross heifers for beef cows. 

In Table 6.4, the ‘target market’ represents the production system or market to which the 

Index Value and the Breed Average Index Value relate. 

Before selecting a bull using the BreedObject Index system, the buyer must determine 

which Index best represents the production system or target market that he/she is most 

likely to be using or supplying. Table 6.4 displays three such scenarios; the Hereford 

Export/Maternal, the Hereford Prime/Maternal, the and the Hereford Dairy/Maternal. Having 

decided which Index to use, the next step is to select the highest ranking bull available 

within this Index. As long as the animal is structurally and reproductively sound, the 

balance of EBVs that make up the Index should be acceptable. 

Table 6.4: Examples of BreedObject selection index values for an example bull vs. the 

breed average. 

Target market $ Index Value Breed Average 

A Export/Maternal ($) +$44 +$34 

B Hereford Prime/Maternal ($) +$54 +$40 

C Dairy/Maternal ($) +$34 +$20 

A bull buyer producing heavyweight carcasses for export would most likely target Bull A in 

Table 6:4 with an Index value of $44. Note that the Hereford breed average for this Index is 

$34. If Bull A and an average bull for this Index were each mated randomly to 160 cows 

during their lifetimes, Bull A would be expected to produce $800 ( ($44-34)/2 x 160 ) more 

profit during his lifetime than an average bull with an Index of $34. Therefore the buyer 


100 

could afford to pay $800 more for Bull A than an average bull and still be just as financially 

well off. Remember, the profit difference between the two bulls must be divided by 2 

because the bull only supplies half his offspring’s genes. 

6.5 Selecting breeding females 

The most rapid progress in genetic improvement of a beef herd is achieved through 

accurate and effective bull selection. On average, each sire passes his genes onto about 

50-150 calves during his working life, while each female passes on her genetic make-up to 

only 5-10 progeny in her lifetime. However, although commercial breeders should be 

concerned mostly with bull selection they still need to make decisions on which heifers to 

retain as replacements in their herd. 

Selection of breeding females can increase the level of desirable traits in the herd. Through 

female selection, producers can improve fertility, weight of calf weaned, the subsequent 

growth of weaned animals and the ultimate value of the sale animals through carcass 

quality etc. Improvements in fertility and survival will increase sale numbers. Selection for 

environmental adaptation, growth rate, temperament, structural soundness and carcass 

traits will affect the price achieved or the relative value of sold animals. Factors such as 

environmental adaptation, including resistance to diseases and parasites, and higher 

growth rates will affect the cost to produce each animal to sale weight. There are three 

opportunities to select females: pre - and post-mating and at first weaning. Pre-mating 

selection removes poor performers from the herd. Selection either allows culls to be 

replaced by more productive females, or allows the remaining productive animals access to 

more feed. 

Pre-mating selection 

The number of replacements required for a beef cow herd is determined by: 

current herd reproductive performance; 

herd policy for culling and selection 

- culling for age 

- culling for reproductive failure 

- culling for non, or poor performance in other production traits; 

maximum cow age; 

annual culling and mortality rates. 


101 

Higher reproductive rates allow increased culling for performance and/or a lower heifer 

retention rate. Some farmers mate excessive members of heifers and treat surplus animals 

as meat producing “once-bred-heifers”. 

At this stage only those heifers with obvious bad temperament, structural faults or low 

growth rates that will severely impede their survival or their ability to reproduce and grow 

should be culled. The remainder of the heifers should be mated for a sufficient period and 

the required number of pregnant replacements retained. 

Post-mating selection 

Post-mating selection is primarily concerned with identifying productive females. Selection 

here is on pregnancy test. 

Selection at first weaning 

There are a limited number of times during the year that cows can be evaluated for 

productivity (e.g. kg calves weaned / kg cows mated). The best times are at weaning and 

during pregnancy testing. Culling criteria might include: 

Fertility: Failure to become pregnant, particularly if not lactating, and failure to 

produce a live weaner are the most critical criteria. In some intensively managed 

herds with a short-period of calving, cows that produce lighter or lower quality calves 

may also be culled. 

Structural soundness: Culling for unacceptable temperament and structural faults 

such as malformed teats should be on-going during the life of the female. 

Mothering ability: Mothering ability is the female's ability to feed and look after her 

calf. Some females will abandon a calf after birth or become separated from the calf 

later on. The ability to protect the calf from predators is also a factor in mothering 

ability. Culling cows that fail to wean a calf removes poor mothers. 

Cow efficiency: This is based on calf weaning weight relative to cow weight. This 

requires calves to be identified with their dams, therefore, most farmers do not 

select for cow efficiency because of the practical difficulties of doing this. See 

Chapter 2 for more details. 


6.6 Evidence of genetic progress 

102 

Growth rate has been and remains the primary selection criterion for most beef cattle 

breeders because it is easy to measure and is related to efficiency of production. Research 

at several locations around the world has shown that selection for high (low) growth rate 

produces heavier (lighter) animals than random-bred controls. In one trial in USA, genetic 

progress continued for 65 years of selection in Hereford cattle, although responses are 

diminishing primarily due to decreasing generation interval. 

The best New Zealand example comes from an experiment established in 1971 on hill 

country at Waikite near Rotorua (Baker and others (1990) and Morris and others (1992)). 

This experiment had three closed herds (no outside genetics introduced) of Angus and 

Hereford selected for (1) adjusted 13 month weight, (2) 18 month weight and (3) random 

selection. Annual responses in liveweight in the selected herds were 0.48% to 0.96% 

greater than in the randomly selected control herds. This is an actual difference of up to 

1.06 to 2.12 kg/year over the 14 year period of calvings. 

One of the frequently asked questions is what were the associated or correlated responses 

in other traits while this single selection for growth rate was occurring? Six correlated 

responses were observed in the Waikete trial. 

1. Cow weight - selection for yearling or 18 month weight resulted in mature cows that 

were 7.5% and 8.2% heavier respectively than the randomly selected control herd. 

2. Calf birth weight – selection for growth rate increased birth weight 

3. Scrotal circumference - selection for yearling weight or 18 month weight increased 

scrotal circumference. 

4. The selected herds were taller as measured by height at withers. 

5. Intake was measured in a sample of bulls after 11 years of selection and the 

13 month and 18 month selected bulls had silage intakes that were 10.4% and 

11.7% greater than the control or randomly selected bulls. 

6. In a separate experiment, sires from the selected herds (after 6 years of selection) 

were mated to balanced samples of test cows. Weaning weights from the herds 

created by using sires from the yearling (13 month weight) and 18 month weight 

selected herds were superior by 8.6 kg (5.7%) and 2.2 kg (1.5%) than weaning 

weights from cows sired by randomly selected bulls. 


103 

Breeders that select solely for growth rate need to be aware of correlated responses in cow 

traits such as increased mature cow weight resulting in increased feed intakes, increased 

birth weight and calving difficulty. Selection for growth rate resulted in females reaching 

puberty earlier. Reproductive rate was similar between the lines. 

A subsequent trial (Morris and others 2006) recorded a difference of 70 days ± 6 days in 

age at puberty between ‘early’ vs. ‘late’ puberty selection lines (a difference of 17%). 

Genetic correlations between age at puberty in heifers and cow reproductive traits were 

favourable so that selecting heifers for earlier pubertal age would improve cow reproduction. 

In reality, selecting heifers for puberty is not practical. The correlated response in age at 

puberty for heifers and scrotal size in half brothers was high. Selecting on scrotal size 

would be a more practical way to decrease age at puberty. 

In summary, evidence suggests that selection for growth will result in rapid progress but 

gains in selection for reproductive traits, while positive will be less spectacular. 

Evidence of benefits from selection for carcass and meat traits have not been demonstrated 

in New Zealand. Examples are available from other countries to suggest the practice is 

worthwhile if producers are paid for the improvement. Presently farmers in New Zealand 

are mainly rewarded for carcass weight and as final weight is the main determinant of 

carcass weight, selection for growth remains the primary objective in most breeding 

programmes. 

6.7 Choice of breed 

Breeds differ in their performance attributes for maternal traits (important in breeding cows) 

and growth and carcass characteristics (important in finished cattle). The choice of breed 

for a particular farm will often involve compromises. Sires with different attributes from 

dams can be used to produce calves that exhibit traits from both breeds. An example is a 

large sire over a dairy cross beef cow, e.g. Simmental bull mated to a Hereford x Friesian 

cow. 

Breed comparison trials were undertaken by the Ministry of Agriculture and Fisheries (MAF) 

during the 1970’s. The performance of female crossbred progeny (except Angus which 

were pure-bred and used as baseline for rankings) in these trials is shown in Table 6.5. 

The crossbred cows were bred as yearling heifers to Angus and Beef Shorthorn sires. As 


104 

cows, they were subsequently bred to either Blonde d’Aquitaine, Charolais, Limousin, 

Maine Anjou, Murray Grey or Simmental sires. Table 6.5 demonstrates that productivity of 

the breeding cow up until weaning depends upon both high calving rates and high calf 

weaning weights. The reduced age at puberty of dairy cross animals led to higher calving 

rates as 2 year olds and improved productivity rankings. 

Table 6.5: Performance of crossbred (crossed with Angus or Hereford) cows. 

Source: Morris and others (1993). 

Sire of cow 

Puberty 

(days) 

% cows 

Pregnant 

% calves 

born alive 

% calves 

weaned 

Productivity 1 

(kg) 

Efficiency 2 

(kg) 

3 Angus 395 84 93 73 110 29 

Jersey 339 87 96 78 141 38 

4 Hereford 382 85 91 74 118 29 

Friesian 347 88 95 79 150 36 

Limousin 423 75 95 68 107 27 

Blonde 

Aquitaine 

417 78 94 68 110 26 

South Devon 398 80 96 73 130 31 

Maine Anjou 394 83 93 74 128 30 

Simmental 393 79 93 69 123 29 

Charolais 418 77 93 67 116 27 

Chianina 432 73 95 63 102 24 

1 

Productivity = weight of calf weaned/cow joined 

2 

Efficiency = weight of calf weaned per 100 kg of cow liveweight mated. 

3 

Angus x Angus 

4 

Hereford x Angus 

The breed rankings in Table 6.5 are similar to results from other breed comparison trials 

conducted elsewhere in the world. 

Earlier trials involving at least 12 sires per breed compared the weaning and carcass 

weights of crossbred progeny from Angus or Hereford dams. These results are shown in 

Table 6.6 and demonstrate the effect of breed of sire on the calf. That is, calves sired by 

breeds with larger mature size tended to have higher weaning weights and the highest 

carcass weights. Furthermore, these larger sized sire breeds tended to have leaner 

offspring when harvested at a similar age. 


105 

Table 6.6: Effects of breed of sire on carcass traits in animals at 31 months of age. 

Source: Baker and others (1990); Morris and others (1990. (Dams are either Angus or 

Hereford cows.) 

Breed of sire 

Weaning 

Weight 

(kg) 

Preslaughter 

weight (kg) 

Hot 

carcass 

weight (kg) 

Dressing 

% 

Fat 

depth 

(mm) 

Muscle 

longissimus 

area (cm 2 ) 

Maine Anjou 173 562 294 52.4 5.4 104 

Simmental 174 540 278 51.5 4.5 96 

Friesian 167 561 287 51.4 7.1 93 

Charolais 171 550 290 52.9 5.4 106 

South Devon 168 550 284 51.9 7.4 97 

Chianina 166 523 278 53.3 6.2 99 

Blonde 

Aquitaine 

167 544 289 53.2 5.4 103 

Limousin 160 515 273 53.3 5.4 103 

Hereford 1 

159 504 264 52.5 9.8 91 

Jersey 147 505 252 50.3 8.1 88 

Angus 2 

151 

1 

Hereford x Angus 

489 248 50.9 7.6 91 

2 Angus x Angus 

The animals from these breeds available in New Zealand in 2005 may differ in performance 

from those used in the original MAF trials. However, the important messages from Tables 

6.5 and 6.6 are that the breeds and their crosses can differ considerably in performance 

attributes and no one breed excels for both maternal and growth characteristics. 

The relative ranking of breeds and their crossbred progeny may change from one 

environment to the next (Table 6.7). The performance of some highly productive cow 

breeds can decline as feed conditions deteriorate. It is therefore important to ensure that 

potentially productive cows can be fed accordingly, otherwise production may fall 

dramatically. 


106 

Table 6.7: Efficiency of beef breeding cows (weight of calf weaned/100 kg cow 

liveweight mated in two environments. Source: Morris and others (1993). 

Waikato flat Rotorua Hill 

Hereford x Angus 29 29 

Friesian x Angus 36 35 

Simmental x Angus 33 27 

Limousin x Angus 28 25 

Breed differences have been evaluated more extensively in the Germ Plasm Evaluation 

(GPE) program at the U.S. Meat Animal Research Center (MARC) located at Clay Center, 

Nebraska. More than 26 different sire breeds have been evaluated in seven cycles of the 

GPE program (Table 6.8). Females produced by these matings were all retained to 

evaluate age and weight at puberty and reproduction and maternal performance through to 

7 or 8 years of age. Table 6.8 presents data for breed crosses grouped into several 

biological types based on relative differences in growth rate and mature size, lean-to-fat 

ratio, age at puberty, and milk production 


107 

Table 6.8: Breed crosses grouped into six biological types on the basis of four major 

criteria showing relative rankings. Source: Adapted from MARC Research Progress 

Reports. 

Although the information in Table 6.8 is useful, it should not be considered the final answer 

to deciding which breed to use. A producer needs to recognise that the information in the 

table reflects breed averages; individual animals and herds within the same breed can 

perform better or worse than the average ranking shown. 

6.8 Breeding systems 

There are two basic breeding systems. If the source of replacement females is heifers 

produced in the herd this is a self-replacing system. If heifers are not used as replacements 

this is a terminal system. 


108 

A self-replacing system produces its own replacement females but requires externally 

selected sires. Since replacement females are retained in this system, the cow herd has 

genetics from both herd sires and herd dams. Therefore, if herd sires have traits that are 

undesirable in cows, they will continue to be exhibited; they cannot be hidden in a 

self-replacing system. Both sires and dams in these systems should be similar in important 

traits, without any undesirable characteristics. 

In a terminal system, both replacement females and sires come from external sources. 

However, since heifers produced in terminals are not retained for breeding, there is more 

flexibility in choice of genetic types. Specialised maternal and sire types can be used in 

terminals, since undesirable traits are generally not exhibited. 

6.9 Crossbreeding 

Crossbreeding is an established breeding method used in sheep and beef cattle breeding to 

increase overall productivity through hybrid rigour. However, not all crossbreeding systems 

are able to maximise these potential gains, because some are too difficult to implement 

under commercial hill country conditions, especially in small herds. The challenge is to 

identify crossbreeding systems that are simple and easy to operate in commercial beef 

breeding cow herds. Crossbreeding does not replace the need for continued selection on 

performance; rather, it adds to these benefits. 

Crossbreeding by commercial beef cattle farmers may be practised for the following 

reasons: 

to introduce a new breed 

to take advantage of the superior qualities of two or more breeds 

to combine the qualities of the different breeds 

to take advantage of hybrid vigour 

to make maximum progress in the traits of low heritability 

The benefits resulting from crossbreeding are best achieved through increased fertility of 

crossbred cows and growth rate of calves. In Figure 6.4, it can be seen that if straightbred 

cows reared crossbred calves rather than straightbred calves, on average, there would be 

an extra 8.5% increase in weight of calf weaned per cow mated (e.g. for a 200 kg weaner 

this would equate to 17 kg of extra calf weaning weight). If crossbred dams were then used 

to rear the crossbred calves, a further 14.8% increase could be expected as a result of the 


109 

better maternal environment (due primarily to better fertility and milk production) provided by 

the crossbred dams. Using crossbred dams to rear crossbred calves, the expected extra 

calf weight weaned/cow would be 23.3% compared to straightbred cows rearing 

straightbred calves. 

Figure 6.4: A comparison of percentage increase in calf weight weaned/cow exposed to 

breeding, as a result of mating either straightbred cows to bulls of a different breed (centre), 

or mating first cross cows to bulls of a third breed (right). The results were obtained from an 

experiment involving all relevant crosses among Hereford, Angus and Shorthorn cattle. 

Source: Taylor and Field (1999). 

6.9.1 Alternative crossbreeding systems 

As stated earlier, the maximum benefits from crossbreeding are obtained when using a 

crossbred cow mated to a terminal sire. The following crossbreeding systems are suitable 

for New Zealand beef cattle producers: 

1. Purchasing crossbred heifer replacements 

By buying-in all heifers, all of the cows in the herd can be mated to a terminal sire. 

This results in maximum heterosis of about 23%. A common system used by 

farmers is the purchase of Beef x Dairy cross heifers (Hereford x Friesian or 

Angus x Friesian) as weaned calves. These are mated at 15 months to an easy 

calving sire breed (e.g. Angus, Hereford, Murray Grey, Shorthorn) and from then on 

to a larger terminal sire breed (e.g. Simmental, Charolais, Limousin or South 

Devon). The main disadvantage of this system is the need to organise a reliable 


110 

source of replacement heifers. However, if it can be managed, it is the simplest and 

most effective system. The risk of introducing new diseases onto the farm, by 

purchasing replacements from off-farm, has to be managed. 

2. Three breed specific cross 

This system uses three breeds which should all complement each other. For 

example the first two breeds (the breeding cow) can be chosen to achieve maternal 

heterosis and adaptation to an environment (e.g. Hereford x Angus) whilst the third 

or terminal sire breed such as Charolais or Simmental can produce the most 

acceptable sale animals using growth and carcass characteristics. 

For example, in a 300 cow herd: 

105 of the Angus heifers, 3 year and possibly 4 year old cows (35%) are bred 

to Angus bulls to generate replacement Angus heifers 

75 of the Angus 4, 5 and 6 year and older cows (25%) are bred to Hereford 

bulls to generate Hereford x Angus heifers 

120 of the Hereford x Angus heifers and cows, and aged Angus cows (40%) 

are bred to a terminal sire (Simmental) and all progeny are slaughtered. 

Heifers may go to an easy calving sire (Shorthorn, Saler). 

This system utilises pure-bred and crossbred heifers on the same farm. It is more 

complex, requiring a large herd with at least 3 mating and calving groups. 

3. Rotational crossing (sometimes referred to as criss-crossing) 

In this system two, three, or more breeds of bulls are utilised in a rotational mating 

system. In a two-breed rotation if Breed A cows are mated to Breed B bulls then all 

heifers born to this cross are always mated to Breed A bulls (Figure 6.5). Hereford and 

Angus breeds have traditionally been utilised in this method and can stabilise at around 

67% of maximum heterosis. 

A three breed rotational cross (Figure 6.6) has been used at Limestone Downs farm, 

Port Waikato for over 13 years utilising crossbred cows comprising the Angus, Hereford 

and Friesian breeds. Heifers born from the mating of one of these sires are mated to 

next bull breed in the rotation for the rest of their productive lives. A fourth breed can be 

introduced to a quarter of the herd (usually adult cows) as a terminal sire breed. Some 


111 

results from the Limestone Downs system are given in Table 6.9. These results 

demonstrate the lift in calf weaning weight achieved with no increase in cow liveweight. 

Figure 6.5: Two-breed rotational crossing 

Figure 6.6: Three breed rotational crossbreeding system 

Table 6.9: Cow and calf weaning weights. Source: Lowe (1994). 

Cow Breed Calf weaning weight (kg) Cow weaning Weight (kg) 

Angus/Hereford 220 445 

Friesian/A x H 250 410 

It is worth noting that Friesian cross cows produce high calf weaning weights, but in an 

intensively farmed system the feed required to restore cow liveweight lost during lactation 

has to be diverted from some other enterprise or, preferably from surplus feed that is not 

required by other stock classes. The opportunity cost of this diverted feed needs to be 

taken into account. 


6.9.2 Composite breeds 

112 

The use of composite breeds where 3 to 8 breeds have been interbred to form a new breed 

is a possibility. Research from USA indicates that composite or synthetic breeds may 

maintain as much heterosis as crossbreeds. Operators of large, extensively managed 

operations may also find composite breeding useful because it allows more flexibility at 

mating, (i.e. fewer mating mobs) than other cross breeding systems. 

Most composite breeds contain a breed ratio of 50% British breeds and 50% Continental 

breeds. A four breed composite retains about 75% of the hybrid vigour of a F1 (first cross). 

In New Zealand the use of composite breeds is in its infancy but some are available e.g. 

Shaver Beef Blend and Stabilizer Composites from the Rissington Cattle Company. 

Rissington source composite genetics from The Leachman Cattle Company in USA which 

gives the Rissington Stabilizer composite (a composite of 50% British (Angus and Hereford) 

and 50% European breeds (Simmental and Gelbvieh) access to huge gene pools in the 

USA (e.g. the Leachman group sells over 1500 bulls per year). 

6.9.3 Alternating breeds over time 

With small herds using only one or two bulls, the choice of crossbreeding systems is 

restricted. A normal rotational system cannot be used although buying in replacements 

heifers (system one) is an option. By purchasing a different breed of bull every two or three 

years, the two and three breed rotations may be closely approximated. 

6.9.4 Benefits of crossbreeding 

The relationship between the various mating systems, maximum heterosis retained and the 

increase in weight of calf weaned per cow exposed is shown in Table 6.10. 


Table 6.10: Maximum heterosis expected in progeny (%) for various mating systems. 

Mating system Heterosis retained Superiority over parent breeds 

Individual 

(%) 

113 

Maternal 

(%) 

Weight of calf 

Weaned Cow mated 

(%) (kg) 

Increased 

value at 

$2/kg LW 

Straightbred A x A 0 0 0 200 0 

2 breed cross (A x B) 100 0 8.5 217 34.00 

3 breed cross (A x B) x C* 100 100 23.3 246 92.00 

Rotational crosses 

2 breed 33 67 12.7 226 52.00 

3 breed 86 86 20.0 240 80.00 

4 breed 93 93 21.7 243 86.00 

Composite 

3 breed 67 67 15.6 230 60.00 

8 breed 87 87 20.4 241 84.00 

* For example (Hereford x Friesian) x Simmental 

The prices noted in Table 6.10 have not included a premium for the growth potential of 

crossbred cattle which in the past have resulted in premiums of $0.10-0.20/kg for 

Simmental and Charolais cross cattle. 

6.9.5 Disadvantages of crossbreeding 

Despite all the above there are several disadvantages of crossbreeding: 

Extra management: Crossbreeding systems within a single farm can be 

complicated because at the need to maintain crossbred and purebred cows in 

separate mating groups. 

More precise recording of breeds and breed groups is required. 

Mating policy mistakes such as mating a large terminal sire to heifers may result 

in calving difficulty problems. 


114 

To maximise the benefits from crossbreeding, producers need to: 

Identify the performance characteristics of beef breeding cows and their offspring 

that will best suit their farming system. 

Recognise that breeds differ in their performance attributes for maternal, growth 

and carcass traits 

Choose a breeding system which involves a compromise between breeding and 

growth characteristics 

Take into account their management skill levels and their ability to plan, 

implement and monitor a crossbreeding program. 

Adopt the most simple system within the constraints of crossbreeding and their 

objectives. 


Anon. 2002. Bull Selection. A beef council publication available from Meat & Wool 

New Zealand, PO Box 121, Wellington, New Zealand. 

Anon. 2000. Beef cattle recording and selection. Department of Primary Industries, 

Brisbane, Queensland ISSN 0727-6273. 

Baker, R.L.; Carter, A.H.; Morris, C.A.; Johnson, D.L. 1990. Evaluation of eleven cattle 

breeds for crossbred beef production: Performance of progeny up to 13 months of 

age. Animal Production 50: 63-70. 

Baker, R L.; Morris, C A.; Johnson, D L.; Hunter, J C.; Hickey, S M. 1991. Results of 

selection for yearling or 18-month weight in Angus and Hereford cattle. Livestock 

Production Science 29: 277-296. 

Charteris, P.L.; Garrick, D.J. 1996. Characterisation of beef cattle breeding industry 

structure. Proceedings of the New Zealand Society of Animal Production 56: 

386-389. 

Lowe, K.I. 1994. Managing the high performance beef cow herd - where to next? 

Proceedings of the New Zealand Society of Animal Production 54: 315-317. 

Morris, C.A.; Amyes, N. C.; Cullen, N. G.; Hickey, S. M. 2006. Carcass composition and 

growth in Angus cattle genetically selected for differences in pubertal traits. 

New Zealand Journal of Agricultural Research 49: 1-11. 

Morris, C.A.; Baker, R.L.; Carter, A.H.; Hickey, S.M. 1990. Evaluation of eleven cattle 

breeds for crossbred beef production: carcass data from males slaughtered at two 

ages. Animal Production 50: 79-92. 


115 

Morris, C.A.; Baker, R.L.; Hickey, S.M.; Johnson, D.L.; Cullen, N.G.; Wilson, J.A. 1993. 

Evidence of genotype by environment interaction for reproductive and maternal traits 

in beef cattle. Animal Production 56: 69-83. 

Morris, C.A.; Baker R.L.; Hunter J.C. 1992. Correlated responses to selection for yearling 

or 18-month weight in Angus and Hereford cattle. Livestock Production Science 30: 

33-52. 

Taylor, R.E.; Field, T.G. 1999. Beef production and management. Third Edition. Prentice 

Hall, New Jersey. 

Davis, G.P. 1993. Genetic Parameters for Tropical Beef Cattle for Northern Australia. 

Australian Journal of Agricultural Research 44: 170-198. 

Robinson, D.L.; Ferguson, D.M.; Skerritt, J.W. 1998. Genetic Parameters for Beef 

Tenderness, Marbling and Yield. Proc. 6 th World Congress Genet. Appl. Livestock 

Prod. 


Summary 

116 

Chapter 7: Beef cattle handling and yarding 

Beef cattle need to be moved into and through yards for various procedures. Factors 

affecting good cattle handling include the skill of the handler, the type of animal, its previous 

experiences, and the facilities and the environment. Cattle are social animals and work 

best in small groups. They remember bad experiences but can learn quickly to move 

through yards. With good people and good yards, little effort and no brutality should be 

needed to work cattle. 

The working distance is the distance at which cattle start to move away from humans or 

dogs. It can be used like an accelerator, moving into the working distance will increase the 

speed at which cattle move and moving out of it will slow them down. Cattle have two 

movement lines (balance points); one along their backbone and one in the shoulder-neck 

region. Moving to the left or right of the backbone line will encourage cattle to move in the 

opposite direction. Moving behind or before the shoulder-neck line will encourage a beast to 

move forward or backwards respectively. 

When cattle are yarded something unpleasant almost always happens to them. They learn 

that yards, races, crushes and head bails are to be avoided. 

A range of measures are described to encourage cattle to move efficiently in yards. 


Beef cattle include breeding bulls, beef cows, calves, weaners, store cattle and finishers. 

Dairy bulls may also be reared as beef animals. The number and class of cattle held on a 

property will determine the size and quality of the facilities required and the standard of 

handling skills needed. Managing beef cattle involves moving them into and through yards 

for various procedures. The degree of restraint required for a particular procedure will vary 

depending on stock class and the procedure being undertaken. 

Profitable Farming of Beef Cows Chapter 7: Beef cattle handling and yarding

7.2 Cattle handling: Moving cattle 

117 

The factors that make for good cattle handling (Figure 7.1) include the skill of the handler, 

the type of animal and its previous experiences, and the facilities and the environment. 

Good handling reduces stress and danger for humans and animals, saves time and effort 

and makes working with cattle more enjoyable. Rough handling makes cattle more skittish 

and difficult to handle in future. 

Figure 7.1: The elements of good and safe cattle handling 

The behaviour of beef cattle during mustering and yarding will be influenced by breed, class 

of stock, the frequency of yarding and the style of handling. Cattle that are mustered 

infrequently and are generally observed from a distance will be more skittish but may move 

through yards quickly. Cows with calves may be protective of their calves. Seriously 

aggressive or wild cows or heifers should be culled as their behaviour will affect the activity 

of other animals in the herd. All bulls deserve respect as a bull may become dangerous if 

overexcited. 

Calmness is important in handling cattle safely and effectively. Constant awareness of what 

is happening, and rapid and decisive responses are also necessary. The knowledge 

required for effective cattle management is usually learned early in life, and the experience 

of working with good cattle people is beneficial to all. 

Cattle do not see like humans and have poorer ability to perceive distance and speed of 

movement. A simple change in footing may appear threatening to a cattle beast and it may 

have to put its head down to inspect the ground. Cattle tend to move towards light and do 

not enter dark areas freely. They are social animals and work best in small groups. They 


118 

remember bad experiences but can learn quickly to move through yards. An electric 

prodder should be used sparingly, and only when the animal can actually move forward. It 

may be useful for moving a cattle beast into a crush or head bail. An alternative is to twist 

the tail. If the tail twist is relaxed immediately the animal moves forward it learns to move 

when its tail is touched or picked up even without twisting. Beef cows should be taught this 

as heifers, the key is to relax the twist once the animal starts forward. 

Cattle have two movement lines (balance points); one along their backbone and one in the 

shoulder-neck region. Moving to the left or right of the backbone line will encourage cattle 

to move in the opposite direction. Moving behind or before the shoulder-neck line will 

encourage a beast to move forward or backwards respectively. 

The working distance is the distance at which cattle start to move away from humans or 

dogs. It varies between individual animals and is influenced by previous handling. It can be 

used like an accelerator, moving into the working distance will increase the speed at which 

cattle move and moving out of it will slow them down. 

The level of arousal will influence the behaviour of cattle. Over-aroused cattle may break 

away, go through fences or attack dogs. Keeping cattle at the right level of arousal makes 

handling easy. Cattle dislike a lot of noise, and easily become over-aroused if too much 

noise is used to shift them or move them through yards. Some cattle dislike motorbikes and 

overreact to them. Dogs used for mustering should be kept under control, and tied up away 

from yards to reduce the level of excitement of cattle. After arriving in the yards, cattle 

should be given 20 minutes to settle down before being shifted into forcing pens or 

beginning drafting. The entrance to yards should be wide to allow cattle to move in without 

being too tightly crushed. Bulls especially dislike other bulls coming into their personal 

space: this lifts their arousal level and may cause fighting. 

7.3 Working in yards 

Cattle learn how to move through yards. Newly purchased stock should be moved through 

yards and given the opportunity to learn the way. This will facilitate easier movement by 

these cattle through the yards in future. Yard design facilitates movement. Little things, 

such as a change underfoot or a shadow across a gateway, can cause cattle to baulk 

(Figure 7.2). When cattle are yarded something unpleasant almost always happens to 

them. They learn that yards, races, crushes and head bails are to be avoided. Therefore, 


119 

everything that can be done to encourage movement into races and head bails should be 

done. 

Figure 7.2: The following is a list of reasons why cattle baulk. 

People in the way 

Noise – they hear shouting, clanging or bawling from the front of the race 

Activity - they see activity at the front of the race 

Smells that are unfamiliar or frightening 

Dead ends – such as a loading ramp directly in front of the head bail 

Unfamiliar yards 

Shadows across their pathway 

Change underfoot, such as a change of surface, drains 

Cattle in adjacent pens standing stationary or going in opposite direction 

Sunlight in their eyes 

Drafting cattle is a basic procedure and is usually carried out through a gateway. Slow 

deliberate movements, the restrained use of a piece of alkathene piping or a flag and 

definite encouragement when the animal chosen is headed through the gate is required. 

Eyeing the cattle to prevent movement and ceasing eye contact once the animal moves 

appropriately is important during drafting. 

The arousal level of cattle must be kept low and quiet animals should be drafted away from 

more excited stock. It is usual to draft cows from calves as the former have experienced 

drafting before. Drafting should be from small mobs and when mistakes occur the animal 

should be left in the incorrect mob until the drafting is complete. Harried cattle are difficult to 

draft through a gate as they tend to bunch and are reluctant to separate from the mob. It 

may be better to draft them through a race. 

7.4 Using forcing pens 

Forcing pens are designed to funnel cattle into a race. These should be narrow enough to 

allow cattle to be worked from outside the pen, preferably from a cat walk. It is best not to 

work inside the forcing pen if possible. Forcing pens should never be over filled as this 

prevents cattle from being directed to the entrance of the race. The material underfoot 


should be the same in the pen as in the race. Cattle may baulk at the junction of a dirt 

floored pen and a concrete race. 

7.5 Working in races 

120 

People should not get into races with large cattle, nor should they stick their arms or heads 

into races. If working in a race with small cattle, work should start at the front of the race 

and proceed backwards. The race should be packed tight to prevent stock movement and 

reduce space to kick. Working from a cat walk is preferable to working from the ground as 

being above the cattle offers some advantages. The cat walk and race wall height should 

be sufficient to prevent a person falling into the race. Workers should not bend too low over 

an animal to inject them or to place an ear tag, as cattle may lift their heads suddenly and 

hit the worker in the face. 

It is important to fill a race tightly if cattle are to be treated from a catwalk as this prevents 

cattle moving back and forward as they are treated. Filling is done best by walking back 

along the catwalk and encouraging cattle to move forward through the shoulder balance 

point. An automatic shutting gate at the tail of the race assists with packing the race tightly. 

Cattle move best into straight races if: 

The conditions underfoot do not change 

They cannot see or hear activity at the front of the race 

They can see ahead up to light coming through the head bail 

The sun is not in their eyes 

In a squeeze crush, cattle need to be restrained at the optimum pressure, not too tight and 

not too loose. Cattle remember being hurt by equipment and will baulk at entering them in 

future. 

Catwalks make life easier and safer Journeaux photo here 


7.6 Yard design 

121 

Most yards are square or rectangular in shape with a straight race leading off a forcing pen 

up to a crush and head bail. Newer yards may have circular or semi-circular designs to 

encourage animal flow. Yards should be on flat ground and be well drained. Cattle tend to 

move up a slope, so if the yards are on a slope, use this to facilitate movement into forcing 

pens and races. There should be no large stones or pieces of timber underfoot which may 

trip up people. Bolts should be cut off flush with nuts and not stick out. Boarding should be 

placed to act as a blinker to prevent cattle from seeing outside the yards. 

Boarded up yards, pens and races may encourage quicker movement of cattle, as they may 

head towards possible escape routes through gates and into races. In a straight race the 

leading animal should be able to see right through the head bail. A visual barrier such as a 

loading ramp will act to stop the lead animal two body lengths back and well away from the 

head bail. This is common in yards and it makes getting cattle into the head bail difficult. 

The entry gates into yards should be wide to facilitate entry. Drafting gates should be wide 

enough to allow drafting by two persons without too much difficulty. Corners should be 

boarded up to stop cattle piling up into a corner. Escape routes should be available and 

underfoot should be dry and firm without anything to trip people up. 

One wall of the forcing pen should run straight onto the race and the other should be at a 30 

degree angle. The tail of the race should be straight for 2 or 3 cattle body lengths to 

encourage cattle to enter. The race tail gate should have an automatic latch to make 

closing easy. 

The use of semicircular forcing pens and races may reduce time to move cattle by up to 

50%. Semicircular races and their forcing pens are usually boarded up. This calms cattle 

and prevents them seeing what is happening elsewhere. If the race is semicircular cattle 

enter it thinking they are returning to where they came from. The lead animal moves 

around the race because it cannot see anything else and is looking to escape. Followers 

tend to chase the preceding animal as they do not want to lose sight of it. Cattle in 

semicircular races also move around people who can hit the boarding or poke a stick 

through holes in the boarding to encourage movement. The shape means that cattle 

suddenly come into the crush or head bail without time or space to baulk. Loading ramps 

can come off the semicircular race and not act as a barrier. 


7.7 Conclusions 

122 

The key to working cattle effectively in yards is in the behaviour of people and cattle rather 

than in the design of the yards. Calm, but alert and active people will shift and treat stock 

safely and quickly without difficulty. Well handled and trained cattle respond to quiet 

handling. The occasional wild animal should be culled to prevent bad behaviour spreading. 

Some simple modification to yards may speed up cattle movement and reduce baulking. 

With good people and good yards, little effort and no brutality should be needed to work 

cattle. 

The key areas to encourage cattle to move efficiently in yards are: 

Board up the wall of the forcing pen at the entrance to the race 

Make sure head bail opens onto open space or paddock 

Board up the race 

Make footing similar through forcing pen and race – remove drains and grating 

Board up curved races 

Use small pens so as to work smaller groups of cattle 

Build yards to use a rise in ground to encourage cattle to move forward 

Do not position race so that sun shines down along it during usual working hours 

Board up corners of square yards 

Use rubber tubing to reduce clanging of steel gates 

Hang gates so that they open and close freely 

Use automatic closing gates on back of race and forcing pen 


Stafford, K. J. 1997. Cattle handling skills. ACC Wellington, New Zealand. 

Grandin, T. 2007. Livestock handling and transport. CABI, Wallingford, England. 


123 

Appendix 1: Condition scoring (CS) for beef cows 

Figure A1.1: Areas to observe when Body Condition Scoring (BCS, or just CS) beef 

cows. Note the focus on observing the rear half of the animal. 

Profitable Farming of Beef Cows Appendix 1: Condition scoring (CS) for beef cows

124 

Table A1.1A: Description of different body condition scores (BCS) on a 1 to 5 scale. 

(Refer to photos also: Figure A1.2.) 

Thin 

Condition 

Borderline 

Condition 

Good 

Condition 

Fat 

Condition 

BCS Description 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

4.5 

5.0 

0 Extremely emaciated, and on the point of death 

Very extremely emaciated, with no fat detectable over spine, hips, 

or ribs. Tailhead and ribs project prominently. Serious welfare 

issues. 

Emaciated, emaciation with no fat detectable over spine, hips, or 

ribs. Tailhead and ribs project prominently. Serious welfare issues 

Poor, still emaciated but tailhead and ribs are less prominent. 

Spine still sharp but there is some tissue over the spine. Welfare 

issues. 

Thin, ribs still identifiable but not as sharp to the touch. Some fat 

along the spine and over the tailhead. Efforts should be made to 

improve condition 

Borderline, individual ribs no longer obvious. The spine is still 

prominent but feels round rather than sharp. There is some fat 

cover over the ribs and hip bones. 

Moderate, good overall appearance. Fat cover over the ribs feels 

spongy and areas on either side of the tailhead have fat cover. 

Moderate plus, firm pressure must be applied to feel the spine. A 

high amount of fat is present over the ribs and around the tailhead. 

Good, cow appears fleshy and carries some fat. Spongy fat cover 

over the ribs and around the tailhead. Fat patches are becoming 

obvious. 

Fat, fleshy and over conditioned. Spine almost impossible to 

palpate. Large fat deposits over ribs, around tailhead, and below 

vulva. Patchy fat. 

Extremely fat. Tailhead and hips buried in fat. Bone structure no 

longer visible. Animal’s mobility possibly impaired, welfare issues. 


125 

Table A1.1B: Description of different condition scores (CS) on a 1 to 10 scale. (Refer to 

photos also: Figure A1.2) 

CS Description 

1 

Short ribs prominent and sharp, absolutely no fatty tissue over spine, 

hips or ribs, tail head and ribs project prominently, severe welfare 

issues 

2 No fat felt, welfare issues 

3 

4 

5 

6 

7 

8 

9 

10 

Short ribs are sharp to touch and easily distinguished, animal is very 

thin 

Some fat on the pins, the backbone is bumpy, i.e. you can see the 

individual backbone notches. 

Can identify short ribs individually, feel rounded, hips and pins are 

rounded, backbone is flat not bumpy 

Can only feel the short ribs with firm pressure. Fat cover is easily felt 

on tail. If cannot feel short ribs and the loin is rounded go above CS 

6, if not go below CS 6. 

Backbone can only be felt by pressing down firmly – back is flat 

across loin. 

Short ribs cannot be felt, even with firm pressure Light rounds of fat 

on tail, soft to touch 

Short ribs completely covered in fat, tail head buried in fatty tissue, 

obese 

Heavy and lumpy covering of fat over the hips, pins, backbone and 

ribs, very obese 

The five occasions when it may be beneficial to condition score beef cows are: 

Weaning time - this ensures young cows (heifers) are given priority if they are in 

poor condition 

30-45 days after weaning - to see how feeding is going and adjust accordingly 

60-90 days prior to calving - last opportunity to get things correct prior to calving 

Calving - separate the thin cows and priority feed these 

Mating - gives an indication of next year’s production levels 


126 

Target liveweights and CS for beef cows on three different types of land, at critical times of 

the year (weaning, mid winter, pre-calving and mating) are shown in Table A1.2. The three 

different cow sizes corresponding to different land could also represent different sized cows 

or breeds. 

Table A1.2: Target seasonal liveweights and CS for various land types. 

Weaning Mid Winter Pre calving Mating 

Hard hill country 430 380 400 410 

Easy hill country 470 420 440 450 

Good Conditions 550 500 520 530 

Condition Score 


3 - 3.5 2.5* 2.5* 2.5 - 3.0 

Condition score 


6+ 5* 5* 5.5 

* These condition score values are somewhat negotiable, provided the cow is fit and 

healthy, has good blood magnesium levels and can gain weight to reach the mating 

condition score targets shown. 


127 

Figure A1.2: Photos of Simmental cows showing various condition score values for both 

0 to 5 and 1 to 10 scales. 

CS 2.0 (4) CS 2.0 (4) 

CS 2.5 (5) CS 3.0 (6) 

CS 4.0 (8) CS 4.0 (8) 


128 

Appendix 2: Nutrient composition of commonly available feeds 

for cattle and sheep 

Feedstuff 

DM 

(%) 

Cr protein 

(g/kg DM) 

ME content 

(MJ/kg DM) 

Mineral content (g/kg DM) 

Ca P Mg Na 

GREEN FEEDS 

Grass/clover mixes 

Spring, leafy 14 240 11.8 6.0 4.5 1.5 1.5 

Summer, leafy 20 150 10.0 8.5 4.0 2.0 2.0 

dry & stalky 25 100 8.0 7.0 3.0 2.0 1.0 

Winter, autumn saved 17 200 10.0 7.0 4.0 1.8 1.5 

leafy 14 260 11.2 7.0 4.5 1.5 1.5 

Kikuyu grass, summer 22 140 8.5 6.0 3.9 1.8 0.6 

Lucerne, leafy 18 280 12.0 16.0 3.0 2.5 0.6 

10-20% flower 23 220 10.0 13.0 2.8 2.4 0.5 

Maize, 1.3 - 1.6m 22 90 10.3 4.0 2.5 1.5 0.2 

Oats, leafy 18 180 12.3 6.0 3.0 1.5 4.0 

Paspalum, leafy 18 180 10.5 7.5 4.0 2.5 0.6 

flowering 23 100 9.3 5.6 3.0 2.5 0.4 

Red clover, spring 17 280 11.5 11.0 3.5 3.0 0.8 

Sorghum, Sudax (1m) 20 180 10.0 4.7 2.3 2.0 0.2 

Tama ryegrass 12 240 12.0 4.0 4.0 1.5 2.5 

White clover 15 280 12.2 12.0 4.0 3.0 3.0 

SILAGES 

Pasture, high quality 23 200 10.0 7.0 4.3 1.7 1.7 

Pasture, poor quality 28 150 8.0 5.5 2.8 1.4 1.6 

Lucerne 20 200 9.5 10.0 2.6 2.0 0.5 

Maize, early dent 30 80 10.3 3.0 2.0 1.2 0.1 

HAYS (pasture) 

good quality 85 170 9.7 8.0 4.0 2.0 2.0 

medium 85 110 8.5 6.0 3.5 1.9 1.7 

poor 85 70 7.3 4.0 3.0 1.8 1.5 

Profitable Farming of Beef Cows Appendix 2: Nutrient composition of commonly available feeds for cattle and sheep

Feedstuff 

STRAWS 

DM 

(%) 

129 

Cr protein 

(g/kg DM) 

ME content 

(MJ/kg DM) 

Mineral content (g/kg DM) 

Ca P Mg Na 

Barley 85 40 6.5 3.0 0.8 1.7 1.1 

Maize stover 85 50 7.5 6.0 1.0 4.5 0.7 

Pea 85 80 7.0 16.0 1.2 - - 

Ryegrass 85 60 7.5 4.0 3.0 1.5 1.5 

CROPS/BYPRODUCTS 

Carrots 12 9.9 13.2 0.4 0.4 0.2 1.0 

Choumoellier 15 145 11.5 15.0 2.4 2.7 3.3 

Fodder beet 18 100 11.5 1.2 1.7 - - 

Mangolds (roots) 10 100 11.5 1.5 1.8 2.0 6.0 

Potatoes 24 90 12.0 0.3 2.5 1.0 1.0 

Pumkin 8.4 16 12.9 0.3 0.5 0.1 0.0 

Rape 17 160 12.0 15.0 4.0 0.7 0.5 

Swedes, bulbs 10 120 12.4 1.3 2.0 2.0 1.0 

tops 15 150 12.8 25.0 2.7 4.0 2.0 

Turnips, bulbs 9 150 12.4 6.0 3.0 2.0 2.0 

tops 13 180 12.8 35.0 3.4 4.0 3.0 

Barley 86 110 13.0 0.6 4.4 1.8 0.3 

Bran (wheat) 86 160 9.8 1.0 12.0 6.0 0.4 

Linseed cake 87 300 12.0 4.4 8.0 6.0 0.7 

Lucerne meal 87 200 11.0 16.0 3.0 3.0 1.5 

Maize 86 80 13.6 0.03 4.2 2.0 0.03 

Oats 86 130 11.5 1.1 3.9 1.4 0.1 

Palm kernel extract (PKE) 90 16 11.0 0.3 0.7 0.3 0.0 

Peas 87 240 13.0 1.4 4.3 1.7 0.1 

Skim milk powder 94 350 13.0 12.5 10.0 1.2 6.0 

Soya beans 90 500 12.9 2.7 5.5 2.6 0.1 

Wheat 86 130 12.6 0.6 4.0 1.6 0.1 

MISCELLANEOUS 

Brewers grain 24 230 10.0 3.0 6.0 1.0 2.0 

Molasses 75 40 12.0 12.0 1.0 4.3 1.5 

Urea 99 2875 - - - - - 

Profitable Farming of Beef Cows Appendix 2: Nutrient composition of commonly available feeds for cattle and sheep

Meat & Wool New Zealand 

0800 696 328 

www.meatandwoolnz.com

Profitable Farming of Beef Cows - Beef + Lamb New Zealand

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