Estimation of genetic and phenotypic parameters in a closed ...

ESTIMATION OF GENET]C AND PHENOTYPIC PARÁMETERS 

IN A CLOSED POPI]LATION OF SIÎINE 

by 

Fang Tsong Lin 

A Thesis 

SubûÉtted to 

The University of Manitoba 

in Partial Fulfillment of the Requirements 

for the Degree of 

MASTER OF SCIENCE 

19 B0

ESTII'iATION OF GENETIC AND PHINOTYPIC PARAMETTRS 

TN A CLOSED POPULATION OF SW]NE 

D \/ 

ut 

FANG TSONG LIN 

A the sis sLrbnlittecl to the Faculty of GradLrate stLrdies ol 

t¡e Urriversity ol ìrlanitoba in partial fLrlfillnlent of tlie reqttirettle'nts 

of the degree of- 

IlASTIR OF SC I ENCI 

o l9B0 

Pernrissioir has bcen grantecl to thc LliliìAIìY oF TIIE UNIVEIì- 

SITY Otr Ì\'IANITOBA to lcnd or sell copics ol'this the sis' to 

the n-ATIOI.\¡\L LIBIìAIìY Oi- CANADA to Inicr.filrÌ this 

tliesis ancl to lc-nd or scll copics olthc'liil]r. and UNIVERSITY 

N,llCROFiLltlS to pLrblish an abstract of this thesis' 

The aLrthor reserves other pLrblication rigltts. arld lteithe r tlie 

thCSis lior t'rtcnsivc ùXtriìCtS lì'r.)lll it ¡l.l¿tt,Lrc llrilttt'cl or otht.rrvisc 

rellrocìrrcecl rvjtiioLlt tlte autltol''s writt.,'ll ¡lertttissiort.

ACKNOI^rLEDGÐ{ENTS 

The author wishes to express his gratitude to Dr. R.J. Parker 

for hís invaluable advice and guidance during the period of graduate 

Study and the preparation of this thesis. 

I am also grateful to the staff members of the Livestock Division 

of AgrÍculture Canada and the personnel of Canada Packers Límited, 

iÎinnipeg, Manitoba for providing assistance and facílities for carcass 

measurements.

11 

ASSTRACT 

Phenotypic and genetic parameters of some reproductive traits in 

swine were estimated from 1 ,264 Lrtters of first 

parÍty }lanagra gilts 

farrowed between L967 anô, 1977. Means and standard deviations for the 

traits of total number of pigs born, number born alive, number at 

weaning, average birth weÍght and average weaning weight were: 9.681 

2.22, 9.L7!2.L3, 7.68!2.L6, 1.3410.18 kg and 10.66!I.52 kg, respectively. 

SignÍficant dÍfferences were observed among three different farrorn'ing 

groups and among years in all reproductive traits. 

HeritabilíÈy 

estimates r,rere as follows: total number of pigs born, 0.0710.12; 

number of pigs born alive, 0.0210.12; number of pigs weaned, 0.0110.12; 

average birth weight, 0.36t0.11; and average weaning weight, 0.3710.11. 

PhenotypÍc correlations among the three different litter 

size traits 

were highly positive and the correlation between average birth weíght 

and average weaning weight was moderately posÍtive. Phenotypic correlations 

between litter si-ze' traits and average pig r.igfrt traits were 

moderately negative except for the correlaËion of nr:mber weaned r¿ith 

average bírth weight. Genetic correlations between total number born 

and average pig weight at birth and at weaning were 0"3010.46 and 0.92! 

0.09, respectively. Genetic correlations betv¡een average weaning 

weight and nr:mber of pigs weaned and average birth weight r,¡ere 0.5211.05 

and 0 .77x0.20, respectively. 

Phenotypic and genetÍc parameters for carcass aeasurements and age 

to market weight were estimated from data on 1r455 Managra pigs consisting 

of 425 barrows and 1,030 gilts over a seven year period (1971- 

1977). Means and standard devÍations for 10 traits \^rere as follows:

iÍi 

carcass length,77.22!2.47 cm¡' maximum shoulder fat thíckness, 4.1710.50 

cmi mininsrn mid-back fat thickriess, 2.01t0.37 cur; loin fat thickness, 

3.2L!0.42 cm; total fat thickness, 9.40tL.04 cm;1oin eye area,30.171 

2 

3.70 cm-; grade index, 101.84t2.80; 7" lnam weight, 26.6911.62; lnam 

surface area, L25.25!L5.34 "*2; 

and age Lo market weight, 188.40115.06 

days. T'he differences between barrorvs and gilts.\^rere significant for 

all c.arcass trait.s and age to market rveight. Heritabilities 

estimated 

from sire and. dam components Treïe: carcass length, 0.62!0.08; maxímum 

shoulder fat, 0.39t0.07; rninimr:m mid-back fat, 0.3310.07; loin fat, 

0.24!0.07; total fat thickness,0.4510.07; loin eye area,0.5310.07; 

grade index, 0.4910.07; % ham weight, 0.24!0.07; harn surface aÍea, 0.41t 

0.07; % predícted yíe1d, 0.56t0.08; and age to narket weight, 0.59t0.08. 

Phenotypic and genetÍc correlation coefficÍents r¡ere calculated from 

analysis of covariance. Several genetic correlation coefficients r¿ere 

outside the theoretical range and the standard errors for most of the 

genetic correlatÍon coefficients were hÌgh. Phenotypic and genetic 

correlatíons among eleven traits were in the same direction buÈ genetic 

correlations tended to be higher.

1v 

TABLE OF CONTENTS 

Page 

ACKNOiÎLEDGEIßNTS 

LIST OF TABLES 

LIST OF A?PENDICES 

INTRODUCTION 

LITERATURE REVIEW 

}-ÍATERIALS AND METHODS 

A. Sources of Data 

I. Reproductíve traiËs 

II. Carcass measurements 

and age to m¡rket weight 

í 

vi 

vaaa 

I 

2 

L4 

I4 

L4 

T7 

B. Statistical Analysis 22 

I. Reproductive traits 

1. Heritabilíty estimates 

2. Phenotypic and genetic 

correlations 

22 

22 

24 

II. Carcass measurements and age to market weight 

1. Heritability estimates 

2. Phenotypic and genetic correlations 

RESULTS AND D]SCUSSION 

A. Reproductive traits ...;. 

I. Means and standard devialions 

II. Heritability estimates 

III. Phenotypic correlations 

IV. Genetic correlations 

26 

¿1 

29 

33 

33 

33 

36 

JÕ 

40

TABLE OF CONTENTS 

Page 

B. Carcass measurements and age to market weight 

I. Means and standard deviations 

II. lleritability estimates -.. -. 

III. Phenotypic correlations 

fV. Genetic correlations 

SU}ßIARY AND CONCLUSION 

LITERATI]RE CITED 

APPENDIX 

40 

40 

4¿ 

47 

/,o 

53 

56 

59

va 

L]ST OF TABLES 

Table 

I Sunrmary of heritability estirnates of reproductive 

traits 

Page 

4 

| $smmery of heritability estimates of carcass measuremenÈs 

and age to market weight traits 

3 Managra breed development pattern and the current 

farrowing groups 15 

I 

4 Number of litters contributíng to the study per 

year per group 

5 Nr:mber of observations contributed to Lhe study 

per year per group 

6 Regression coefficients used to adjust carcass 

Deasurements for carcass weíght 

L6 

Z0 

ZL 

7 Analysis of variance for litter size 23 

B Analysís of covariance 24 

9 Analysis of variance 27 

10 Analysis of covaríance . 29 

11 Means and standard deviations of reproductíve traiÈs 

for each farrowing group for 10 years 34 

12 Means and standard deviations of reproducËive traítsfor 

eaeh year 35 

13 Escimated heritabilitíes and their standard errors for 

each of five reproductive traits from the sire 

cornponent of variance 

L4 

Phenotypic and genetic correlations among reproductive 

traits 39 

37 

15 Means and standard deviations of carcass measurements 

and age to market weight for each sex . 

4L 

16 Means and standard deviations of carcass measurenents 

and age to markeÈ weight traits for each farrowíng 

group 43

va1 

LIST OF TABLES 

Table 

Page 

L7 Means and standard deviations of carcass Illeasurements 

and age to market weight traíts for each year 44 

18 Heritability estim¡tes for carcass measurements and 

age to market weight traits 46 

19 Phenotypic correlations among nine carcass measurements 

and age to market weight traits 48 

20 Genetic correlations ainorlg carcess Eeasurements 

and age to m¡rket weighË 50

vaal, 

Appendix 

I 

II 

III 

LIST OF APPENDIX TABLES 

Analysis of variance of reproductive traits . .. 60 

Analysís of covariance of reproductive traits ... 67 

Page 

Analysis of varíance of carcass rneasurements 

and age to rnarket weight 63 

IV 

v 

VI 

Analysis of covariance of carcass measurements 

and age to m¡¡l¡s¡ weight 64 

Table of differentials for carcass grade index 75 

Adjustment table for age to urarkeË weight 76

INTRODUCTION 

The heritabilíty 

of traits of economic importance is a fundamental 

source of information in the theory and practice of swine breeding 

programs. 

Phenotypic and genetic correlations among the traits are t\ro 

essential factors for constructing selection indexes vhen several 

traits are involved in the same program at the same time. 

In this study five reproductive traits, 

ten carcass measurements 

and age to market weight were considered ín the determÍnation of 

heritability estimates and in the computation of genetic and phenotypic 

correlatiorrs among traits in Managra pigs. The five reproductive 

traits rüere total number of pigs born, nurnber of pigs born a1ive, 

number of pÍgs weaned, average pig birth weight and average pig weaning 

weíght. The ten carcass Ðeasurements included: carcass length, 

maxímum shoulder fat thíckness, minimum mid-back fat thíckness, maximum 

loin fat thickness, total fat thickness, loin eye area, grade index, 

peïcent ham weight, ham surface area and percent predicted yield of 

trínrmed cuts.

LITERATURE REVIEI^] 

A. 

Reproductive Traits 

I. Heritability EstÍmates 

It has been well recognLzed that characters closely related to 

reproductive fitness have low heritability 

estimates. Some of the heritability 

estimates reported by differenË workers are listed in Table 1. 

Heritability estimates from the literature range from -0.03 to 0.11, 

-0.01 to 0.28, 0.04 to 0.29, -0.04 ro 0.27 ar'ð.0.02 ro 0.46 for roral 

number of pigs born, number of pigs born alive, number of pigs weaned, 

average birth weight and average weaning weight, respectívely. 

An 

exception to the above range has been reported by young et al. (1978) 

from an analysis of data rlom 2,095 gilts. These workers reported high 

heritabílities of 0.72!0.22 and 0.66!0.23, for total number of pigs born 

and ni¡nber of pigs born alive, respectively. young et al. (197S) cited 

that Po¡ofrey et al. (L975) utilized six seasons of data instead of eight 

from the sane population and reported heritabilitíes 

of 0.0910.08 and 

0 .0910.09 f or these trrTo traíts . 

Revelle and Robison (1973) examined data from 1,078 two-generation 

and 710'three-generation pedigrees to find the causes of 1ow heritabilities 

of reproductive traits. The gilts were dívided into three 

groups as high (78"/"), nr-iddle (647") and 1ow (r9i() based on rhe firsË 

generation litter size. The daughterrs litter size of the 1ow group exceeded 

the high and the niddle groups. The results suggested a negative 

environmental correlation between the litter 

size of dam and daughter. 

Heritabilíty estinates for litter size at birth were 0.13t0.06 from the 

regression of daughter on dam and 0.2810.26 from the regression of

granddaughter on granddam. The heritability 

estimated from granddaughtergranddam 

regres.sion \¡las two times as large as the one estimated from 

daughter-dam regression. This result also indicated the presence of 

negative m¡ternal effec.ts on litter size, The authors suggested that the 

physiological maturation of the gilts from large litters 

was delayed 

by stress and competition. The explanation by the auËhors for the low 

heritabÍlity estiuntes of litter size were as follor¡s: 

1) srnall addÍtive genetic variance 

2) excessive environmental varíabilÍty 

3) negative correlations between direct genetic and maternal 

effects or negative genetíc correlations between component.s 

of the traits. 

Research on the Managra breed developed at the University of 

Manitoba \,ùere reported by stockhausen and Boylan (L966), Roy et al. (1968) 

and Krotch (f975). Stockhauseri and Boylan (1966) reported an estimate 

of 0.1910.16 for the heritability of litter size. Krorch (]-915) investigated 

333 Managra litters consisting of. 775 group A which farrowed 

in June-July, 1968-L973 and 158 group B litters farrowed in January- 

February, 1969 to r974. The herítability estimates of reproductÍve 

traits for each of the t\,/o groups vrere: -0.0310.02 and 0.05t0.03 for the 

total number of pigs born, -0.0110.02 and 0.03!0.03 for rhe number of 

pigs born alive, 0.0410.04 and 0.0910.02 for the nirmber of pÍgs at 3 weeks 

of age, 0.0410.15 and 0.11t0.15 for indivÍdual birrh weighr, and -0.16+ 

0.14 and 0.25!0.17 for individual 3 week weíght. Roy er al. (1968) 

reported that the heritability of pig birth weÍghr was 0.1010.15.

Table 1. Surnmary of herltabil-1ty estlÍìates of reproductive tralts 

Traltg 

.2 h 

MeEhod of estLmaElon 

No. of observatlons 

Refe¡ence 

Total rio. born 

0 . 094{ .04 

0.11 

Dam-daughter regresslon 

Pooled 

3,78L 

ist 

Urban eL a1. (1966) 

Fahmy and Bernard (1972) 

-0,03]{.02 

-0.05J{.03 

0.72+4.22 

Half-s1b correlaLlon 

Half-sfb correlaElon 

175 

158 

2,095 

Krotch (1975) 

Young et a1. (1978) 

No. born al-1ve 

0.03r{.07 


1,959 

Boyl.an et al. (1961) 

0.20-rc.15 

0.59{{. 29 

Dam-daugh ter regresslon 

Half-stb correlatlon 

304 

304 

Stockhausen and Boylan (1966) 

0.08+0.04 

0.07r{).02 

0.09 

0.13r{.06 

0.2814.26 

-0 .01r{.02 

0.03r{.03 


Dam-daughEer regresslon 

Pooled 

Dam-daughter regressJ-on 

Granddam-granddaughter re gress lon 

Half-sib correl-aE1on 

3,78L 

3B, o0o 

75r 

750 

539 

L75 

158 

Urban et al. (1966) 

Strang and Ktng (1970) 


Revelle and Robtson (1973) 

Krotch (1975) 

0 .7 2+4 .22 

Half-sib correlaÈ1on 

2,095 

Young et al. (1978) 

No. pigs weaned 

0.13r{ .05 

0.09-rc.03 

0. 15 

Dam-daughLer regresslon 


Pooled 

t 701 

38,000 

75r 

Urban et a1, (1966) 

Strang ancl Klng (1970) 

Fahmy antl Bernard (1972) 

0.04]{ .04 

0 .09r{.02 

0.29+4.25 

Half-slb correlatlon 

Half-slb correlatlon 

t75 

158 

2,O95 

Krotch (1975) 

Young et a1. (1978) 

. , Contlnrrecl

Table 1 (Contlnued) 

Tralcs 

a 

n 

Method of estlr¡ation 

No. of observatl-ons 

Reference 

Plg blrth LrelghL 

0.0il{.35 

0.2714.06 

0.17 

0.0410.04 

-0 . 04{{ .04 

0.001{.03 

0.16J{.16 

0.10+0. 15 

Half-s1b correlaElon 

Regresslon of offsprlng on mid-parent 

Pooled from above Er,¡o esÈfwrtlons 

Regresslon of offsprlng on slre 

Regresslon of offsprlng on dam 

Regreeslon of offsprlng on n1d-parent 

Half-efb correlaElon 

Half-sib correlatfon 

6,846 

3,760 

2,095 

r,246 

f'ahny and Bernard (1970) 

Edr¿ard 

Young 

Roy et 

and Omtvedt (1971) 

et al. (1978) 

a1. (1968) 

Plg weaned welght 

o.r4+4.26 

0.08r{.04 

0.1r 

0.08-m.04 

0.02{{) .04 

0. o5i{.03 

0.46{{.19 

0.18+0.15 

Half-s1b correlaclon 

Regreselon of offsprlng on mld-parenE 

Pooled from above Ëwo esÈlmaE.1ons 

Regresslon of offspring on sire 

Regressfon of offsprlng on dam 

Regresslon of offspring on mid-parenE 

Regresslon of offsprlng on dam 

Half-sfb correlatlon 

6,846 

2,956 

38,000 

2,O95 


Edward and Omtvedt (1971) 

SErang and Klng (1970) 

Young et a1, (1978)

Heritability estipates of si¡ine reproductive traits are generally 

1ow and ínconsistent. The explanation for the inconsistency may be due 

to Ëhe sampling eïror, the statístical method for estimation and the 

population studíed. 

II. 

Correlations among reproductíve traits 

Strang and King (L970) reported favourable positive phenotypic and 

genetic correlations betr¿een litter size and litter weÍght, with the 

exception of a negative correlation betr¿een litter sLze and the average 

pig weight at weaning. 

Edwardsand Omtvedt (197f) reported high positive phenotypic correlations 

among litter síze traits. Fahmy and Bernard (L972) found that 

litter size (total and alive) at birth and at r¡eaning r,ùere posítively 

phenotypically correlated with litter weight but were negatively correlated 

with individual pig weight at birth and aË weaning. The authors 

explained when the litter size increases, litter weight also increases 

while mean índivídual weÍght decreases due to the competition for the 

nutrient supply from the dau. They also reported that a highly positÍve 

phenotypíc correlation coefficients existed among three litter size 

traits and the individual birth weight was moderately positively correlated 

with individual weaning weight. 

Baik et al. (L974) estimated phenotypic and genetic correlatíons 

among traiLs of litter size and litter weight from data of. 6L4 Landrace 

litters over a three year period. The phenotypic correlation between 

the number of pigs born alive and the total litter weighË aË birth was 

0.812. The total number of pigs born was highly positively correlated

7 

r^/ith the number of pigs born alive and the litter weíght at birth. The 

genetic correlation betr¿een number of pigs born alive and 1ítter weight 

at birth was also hígh1y positive. 

Young eË al. (1978) anaryzeð. data from 2,095 girts and reporred 

phenotypic correlations between litter size and total litter weight at 

birth and at 42 days to be high and positive. 

In genetic correlations, 

pig birth weight was positively correlated with total number born (O .37), 

number born alive (0.35) and nuuber rueaned (0,04). 

The genetic correlations 

between pig weaning weight and lítter 

size at birth (total 

number born and number born alive) were negligible, while a moderately 

negative correlation Ítas found between pig weaning weight and number 

weaned. 

B. Carcass measurernents and age to ma¡]¡s¡ weight 

I. HerÍtabílity estimates 

The suntmary of heritability 

estímates of carcass measurements and. 

age to markeË weight reported frorn different researchers is presented in 

Table 2. rt is clear that the majority of swine carcass traits are 

moderately or highly heritable. HerítabilÍty of carcass length reported 

in the lÍterature ranged froro 0.46 to 0.87 and averaged 0.63. Backfat 

thickness including indivídual shoulder, rnÍd-back and loin fat thickness 

measurement, and the mean frorn ,two or three fat thickness measurements, 

ranged from a 1ow of 0.25 to a high of 0.74 and averaged 0.50. Loin eye 

area ranged from 0.35 to 0.70 and averaged at 0.50. Dressing percentage 

was moderately heritable and ranged from 0.26 to 0.40 with an average of 

0.32. HeritabÍlity of age to market weight (approx. 90 kg) \^¡as reported

Table 2. Summary of herltabllity 

estlmates of carcass measurements and age to rnarket weight traits 

Tralts 

h2 

Mechod of estimatlon 


Refe¡ence 

Carcass length 0.52 

0.78r{.10 

0.87 

0 .50+0 . 16 

0.464n.04 

0.64 

Pooled from paternal, maternalhalf-slb 

and fu11-slb correlaLLon 

Paternal half-slb correlatlon 

il il tr il 

ttililtt 

tr tr It tt 

Pooled frofl paternal- half-sib 

correlatlon and parent-offspring regressfon 

53r 

1,936 

2,296 

7,275 

44,969 

2,031 

Enfleld and llhatley (1.961) 

Smlth et a1. (1962) 

SmlLh and Ross (1965) 

Roy et al. (1968) 

Flock (1970) 

Fahmy and Bernard (f970) 

Backfat thlckness 

. Mean 

Shoulder 

Mid-back 

Loln 

Mean 

Shoulder 

Rtb 

Lofn 

Mean 

Mean 

Mean 

0.63 

0,62r{.10 

o . 73-rc.10 

0.71+0.10 

0.74 

0.26r{.11 

0.43+O.13 

0.zsfl.L2 

0.35r{.12 

0.69-rc.17 

0.s3 

Pooled from paternal, maternal halfslb 

and fu11-s1b correlatlon 

Paternal half-slb correlatlon 

tr[[ 

llItil 

ll il tt 

il[il 

lrltil 

ll il il 

llrfil 

531 

7,936 

2,296 

1 ,191 

585 

650 

Enf íel.d and h¡hatley (1961.) 

Smlrh et al. (1962) 

Smlth and Ross (1965) 

Roy et al. (1968) 

Jensen et al. (1967) 

Arganosa et al. (1969) 

. . Contlnuetl

Table 2 (Contlnued) 

TraÍtg 

h2 

Method of estlMtlon 

No. of observaËlons 

Reference 

Mean 

Mean 

Mean 

Mean 

Mean 

0 . 46J{ .05 

0.67 

0.25 

0.30+0.07 

0.35r{.12 

Paternal half-elb correlatlon 

Pooled frorn paternal half-s1b correlaÈ1on 

and parenË-offeprfng regreselon 

PaEernal half-e1b correlatLon 

tt il tt I 

Irtilil 

44,969 

2,03L 

4,639 

5,952 

L,L94 

Ilock (1970) 

Fahmy and Bernard (1970 

glere and Ihonson (1972) 

Swlger ec al. (1979) 

Roy eE al. (1968) 

Loln eye area 

0.44 

0 . 35r{ .09 

0.t+9 

0.56+4.22 

0.47 

0 . 45rr0 .04 

0.48 

0.70 

0.56r{).06 

Pooled from paternal, maternal half-elb 

and full-elb correlatlon 

Paternal half-efb correlaEion 

trilItU 

trÙil[ 

tr il [ il 

ilililil 

Pooled from paternal half-s1b correlatl-on 

and parent-offsprlng regresslon 

Paternal half-e1b correlatlon 

ll I tt I 

531 

1,936 

2,296 

528 

650 

44,969 

2,O31 

4,639 

5,952 

Enffeld and Whatley (1961) 

Smleh et a1. (1962) 

Smfth and Roee (1965) 

Roy et al. (1968) 

Arganoea et al. (1969) 

Flock (1970) 

Fabmy and Bernard (1970) 

Slers and Thomson (1972) 

Swiger et a1. (1979) 

. Contfnued

l.abLe 2 (Contlnued) 

Tralts 

.2 h 

Method of estimatlon 


Reference 

Dreselng out % 

0.40r-0.09 

o.26 

0.30-Ð.07 

Paternal- half-slb correlatl-on 

rr rr ll 

ll 

, 

il[Itl 

1,936 

2,296 

5,952 

smlth et a1. (1962) 

Smlth and Ross (1965) 

Svfger et al. (1979) 

Age to markeE welght 

0.40{{).07 

0.31J{.12 

illlllll 

Regresslon of rnld-parent and offsprlng 

5,952 

r,244 

Swlger ec a1. (1979) 

Edwards and Omtvedt (1971) 

F 

O

11 

as 0.31 and 0.40 by Edwardsand Omtvedt (I97L) and Srviger et al. (L979), 

respectivery. Research on the }{anagra conducted by Roy et al. (1968) 

reported herítabilíty estimates of 0.501-0.16, 0.35+0 .L2 and 0.5610 .22 for 

carcass length, carcass backfat and loin eye area, respectively. 

II. 

Correlations among traits 

Snith et al. (L962) estimated heritabÍlities 

and correlatíons among 

35 carcass measurements and scores from record,s of L936 British Llhite 

bacon pigs. The authors found that phenotypic and genetíc correlations 

behave sinilarly. The genetic correlatíons are of the same sign as 

phenotypic correlations in most cases, whí1e the absolute values of 

genetic correlations rÀ7ere higher than phenotypic correlations. 

There 

were high correlations among traits from one particular characteristic 

of the pÍg such as shoulder fat thickness and mid-back fat thickness. 

The dressing-ouË percentage shor,¡ed positive correlations with backfat 

thickness and eye muscle area. 

Strith and Ross (1965) estimated heritabilitíes and correlations 

among 26 performance and carcass traits from data involving 21296 British 

Landrace pigs. The genetic parameter estimates r^7ere quite similar to the 

f igures reported by Sinith et al . (L962) on Large ltlhíte pigs. 

Jensen et al. (L967) found that average backfat thickness rùas not 

correlated phenoÈypically or genetically i^rith loin eye area, rvhile the 

percent lean cuts was highly positively correlated r¿ith average backfat 

thíckness and was moderately negatively correlated with loin eye area. 

Arganosa et al. (1969) estimated the genetic and phenotypic correlaËions 

among 13 carcass traits from 650 pigs and showed that selection

T2 

for less backfat thickness would increase percent lean cuts with an 

insignificant effect on loin eye area. Selection for larger loin eye 

area wíl1 increase lean cut yield. 

Flock (1970) studied genetic correlations among traits on 44,969 

German Landrace pigs and reported that carcass length was moderately 

negatively correlated with backfat thickness and had a low negative 

correlation with loin eye area. The correlation betv¡een backfat thíckness 

and loin eye area was moderately negative. 

Siers and Thomsor. (L972) estinated genetic eorrelations among carcass 

traits from records of 3,439 purebred pigs. The result indicated 

that selecting for less backfat thickness will increase loin eye and ham 

and loin percenL and selecting for larger loin eye area will increase ham 

and loin percent effectively. 

Enfield and Ltrhatley (1961) reported that phenotypic correlations 

anong carcass length, backfat thiekness and loin eye area were sm:l1 in 

absolute value with the largest correlation coefficient of -.36 being 

betvreen backfat thic.kness and carcass length and -.27 between backfat 

thickness and loin eye area. The genetic correlaËions among these three 

traits were al1 negative and insÍgnificant. 

Fahmy and Bernard (1970) reported favorable relationships between 

carcass length, backfat thíckness and loin eye area. 

Swíger et al. (l-979) found that lean cut percent had a high negative 

genetic correlation with backfat thickness (-.gO) and a high posÍtive 

correlation with loin eye area (.83). Backfat thickness was moderately 

negatively correlated r¿ith loin eye area both phenotypically and 

genetically (-;34). The phenotypic correlation between lean cufupercent

13 

and backfat thickness r^7as negative (-.33) and the relationship between 

lean cutspercent IÎíth loin eye area was positive (.39). 

Age to 90.7 kg 

live weight v¡as posirively correlated wíth lean cut percent and loin eye 

area both genetically and phenotypically. 

A negative correlation 

(not sÍgnificant) was found between backfat thickness and age to 90 -7 

kg live weight. 

Roy et al . (1968) reported that loin eye aTea \,/as negatively correlated 

with backfat thickness both phenotypically and genetically 

(rO -.16, tG = -.27). Carcass length was positively correlated i,¡íth 

loin eye (r = O.O2, Tn = 0.42) and r¿as negatívely correlated wíth back- 

-P-(' 

faË thickness (tn -.11, ra =-.19).

L4 

MATERIALS AND ìGTHODS 

A. 

Sources of Data 


The data for 1ítter sLze were obtaíned from the records of the 

uníversity of Manitoba swine breeding project over the períod of years 

1967 to L977 at the Glenlea Research Station. First parity gilts of the 

Managra breed rîere included in this study. Managra r¡ere developed 

from a gene pool consisting of about 457á Swedish Landrace , 2O7. IÎessex 

Saddleback, 15% I,Ielsh ar'ð 707. Minnesota //l-Berkshire-Yorkshire-Tarff^rorth. 

Table 3 illustrates 

the pattern of development of the Managra and the 

current farrowing groups (Parker, f977). 

Parents of each generation consisted of 20 to 30 boars and 90 to 

120 gilts. Selection of parents based on backfat thickness as measured 

by adjusted live ultrasonic probe, adjr,rsted age to 90 kg live weight and 

physical soundness. There \¡ras no line crossing among the groups and inbreedíng 

was rulnimized each generation. LitËers from which fewer than 

3 pigs \47ere weaned were not included in the study. The number of liËters 

which contributed to this study from the diffeïent groups in the different 

years are lísted ín Table 4. Total number of pigs born, total 

number of pigs born alive, total number of pÍgs weaned, average bÍrth 

weight and average weaning weight were the five reproductive traits 

examined. Average birth weight and average weaning r^reight were adjusted 

for number born alive and number weaned, respectlvely. 

The adjustments 

were used only rvhen calculating phenotypic means. The equation for 

adjustmenË (Huntsberger, L977) was:

Table 3. Managra breed development patt.ern and the current farrowing groups 

Line 1 

Swedish Landrac 

2aro.rp B f arrows each year in Jan.-Febu 

I{essex 

I'Ie1sh 

45% Sw. Land. 

Mínn. 

20% I{essex 

Berkshire 

157" Welsh 

Line 3 

Yorkshi r 

20% M.BuYnTn 

Tamrn¡ort 

L957 

19s 9 

L967 

Gene Poollctorrp 

A farrows each year in May-June. 

Manaqra 

Managra 

group 

3crorrp C farrows each year ín Sept..-octo 

Generation interval ís one year in each group. 

F 

(Jr

L6 

Table 4. 

Number of litters 

year per grouP 

contributing to the study per 

Year 

Group A 

Group B 

Group C 

r968 

27 

35 

9 

l-969 

34 

37 

26 

L97 0 

40 

39 

32 

L97L 

46 

35 

35 

L97 2 

47 

37 

49 

r973 

35 

58 

39 

197 4 

32 

60 

27 

L97 5 

39 

4L 

31 

L97 6 

40 

53 

9L 

L977 

47 

76 

67 

Total 387 47L 406

L7 

Adjusted Y, = Y. - b (Xt-X") 

where Y- = average birth weight or average weaning weight 

t_ 

X. = total number born alive or total number weaned 

t 

i. = reao of total nurnber born alive = 9.148 

or mean of total number weaned = 7.656 

b = regressíon coeffi_cient 

O.OZLI for average birth weight v¡ith number born alive 

- 0.O462 for average weaning weight with nurnber ¡¡eaned 

Iï. Carcass measurements and age to market weight 

The data used for analysis of carcass measuïements and age to 

merket weight were also collected from the same swine breeding project. 

A total of 1,455 Managra consisting of 425 barrows and 1,030 gilts which 

farrowed during the period 1,97l- xo 1977 were included in thís study. The 

number of pigs contríbuting to the study are listed in Table 5. 

The gilts that ranked at the bottom half of the whole population 

in Record of Performance (ROP) index and all the barror\rs \¡/ere marketed 

when they reached abouË 90 kg live weight. All pigs were killed at the 

1 

same abbatoir*. 

The carcasses I^/ere retained for 24 hours before carcass 

measurements were taken. Carcass traits measured and the procedures 

used for measurement \,rere as follows: 

1) Carcass iÎeight (one side) 

The carcass rías accurately split int.o halves and the head 

and jowls removed. The leaf lard, kidney and tail were 

also excluded from the carcass weight. 

1 Canada Packers Limited, I{innipeg, Manítoba.

1B 

2) Carcass Length 

Carcass length r,ras Ðeasured as the distance between the 

Íore-edge of the first 

rib and the fore-edge of the aitch 

bone section on the cold horizontal carcass. 

3) Maxímum Shoulder Fat Ttríckness 

Measured in nrm at the point of maximum thickness over 

the shoulder. 

4) Ilinimurn Mid-back Fat Thickness 

Measured i¡ rrrm at the point of minímum thickness over Lhe 

back. 

5) Maximuro Loin Fat Thickness 

Measured in nrm at the point of maxjrnum thickness over 

the lumbar region. 

6) Total Fat Thickness 

Total fat thíckness measurements from shoulder, nid-back 

and loin aree-, i.e. sum of measurement.s 3, 4 and 5. 

7) Loin Eye Area 

The logissimus muscle was sectioned beÈween the 7Ëh 

and BËh vertebrae and its area measured using a 

planÍmeter. 

B) Grade Index 

Carcass grade index Lras according to the Table of Differentials 

from Canadian Hog Carcass Grading/Settlement System provided 

by the canadian Pork council. 

The Table of Differentials 

is shown in Appendix V.

19 

9) 'PercenË Ham I{eight 

The proportion of ham in total iøeight of the side. 

The ham is detached at a point 5 cm ahead of rhe foreedge 

of the aitch bone section and at right angles to the 

1ength.line. 

10) Harn Surface A.rea 

Lean area over the ham measured in .*2 .rrd traced by 

a planiueter. 

f1) Percent Predícted Yield of Trirrmed Cuts 

The formula used for this calculation is: 

y = 51.68 - (I.273x, - 0.161x, - 0.485x, - 0.B27xO) 

wherei y = predicted yield (Z) 

xl = total backfat thickness in rr¡m 

x, = loin area ín sq. cm 

*3=%hamweight 

x, : ham surface area ín sq. cm 

4' 

All factors are corrected for sex and carcass weight. 

L2) Aee to MarkeË trrleight 

Nurnber of days to market weight was adjusted to a 90 kg 

liveweight basÍs followi-ng the Canadian ROP home test 

program procedures. The adjusÈrnenË factors are shovm in 

Appendix VI. 

A-ll of the above measurements except grade index, percent predicted 

yield and age to market weight were adjusted for carcass weíSht

20 

Table 5. 

Number of observations contríbuted 

Per year Per group 

to the study 

Year 

Group A 

Group B 

Group C 

L97T 

56 

L57 

B5 

L97 2 

92 

4L 

AL 

L973 

6L 

B6 

103 

797 4 

34 

138 

4B 

r97 5 

46 

B5 

34 

r97 6 

46 

69 

B7 

197 7 

54 

LO 

a) 

ToËal 389 625 447

2I 

Table 6, 

Regression coefficients used to 

measurements for carcass weight 

adjust carcass 

Trai t 

MaI e 

Femal e 

Carcass length (cm) 

Max. shoulder fat thickness (cn) 

Min. back fat. thickness (cn) 

Maxo loin fat thickness (cn) 

Total fat thickness (crn) 

Loin eye area ("*2) 

Ham surface area (.r2) 

0"031823 

0 " 

0063 40 

0" 004982 

0 007 " 

565 

0,01 9046 

0.013218 

o.o1 4248 

0.031564 

0 " 

008 655 

0.005036 

0. 008507 

0 

"021936 

0.020266 

0.110079

22 

on both sexes. 

Adjus ted 

where v. -1 

The formula for this adjustment (Huntsberger, 1977) was: 

Yi = Y. - b (x. - x"¡ 

= carcass measureo,ent on ith ."..r"" 

l_ 

ã.. 

= carcass weight of iËh carcass 

: mean carcass weight 

68.1 kg mean carcass weight for barrows 

68.7 kg mean carcass weight for gí1ts 

The regression coefficients (b) for adjustment are listed in Table 6. 

Carcass rDeasurements of gilts were adjusted to a barrow equivalent. 

The correction factors used for sex adjustlDent were as follows: 

carcass 

length -1.138 cn; shoulder fat thickness *O.244 cm; backfat thickness 

*0.170 crn; loin fat thickness +{.229 cm;'total faË thickness *o.668; 

loin eye area -3. 155 cra2; percent ham weight -0" 632'/"; and ham surface 

t 

area -2.961 cu", respectively 

B. 

Statistical 

Analysis 


Heritabílity estim:tes, phenotypic correlations and genetic 

correlations for reproductive traits r,¡ere estimated from analysis of 

variance and covariance in a nested classification with an unequal 

number of lítters 

per sire within years and farrowing groups. The 

procedures for analysis of variance and covariance in this study fo1- 

lowed the procedures described by Becker (L967). 

l. Heritability estirnates - Heritability estimates were calculated 

from the sire component of variance. The form of anal-ysis of

a') 

variance is given in Table 7. 

Table 7. Analysis of variance for litter 

size 

Source of variation 

Among years 

d"f. 

Y-l 

Sum of 

souares 

(SS) 

tt" 

Mean 

square 

(MS) 

*t, 

Expec ted 

mean 

souare 

Among groups/year 

G-Y 

SS^tr 

MS^ 

\J 

Among sires/group/year 

Litters r¿ithin sires 

S-G 

n.-S 

'S, 

ssw 

"ts 

MS_. 

l^/ 

"'r*""3 

2 

oüI 

where Y = mrmber of years 

G = number of farrowing groups 

S = number of sires 

inY vears 

n. = total number of litters 

Estimation of variance cornponents: 

ofr = us" 

o!:ts,-rr" 

where K = 

* 

^2 Àn. 

n.- l- 

n. 

n. 

l_ 

number of litters 

from the Íth sire 

Heritability 

follows: 

h3 = 

4"3 

22 

os * oIn, 

estimated from the síre component 

(Falconer,1960) as

24 

Standard error 

(Becker, L967): 

of heritability 

was estim¡ted as follows 

s. E. (n3) = 

where S 

abilÍty 

t= 

2 

o^ 

22 

os*ow 

2 (n. -1) (1-r) 2 (r*(x-r) .) 

2 

x2(r,.-s)(S-1) 

, 

E. (h:) is the standard error of the esiimate of heritt 

is the intra-class correlation 

S and K are as previously defined. 

2. Phenotypic and genetic correlations among the traits were calculated 

from analysis of variance and covariance (Falconer, 1960). The 

form of analysis of covariance is given in Table B. 

Table 8. Analysis of covariance 


d.f. 

Mean cross 

products (MCP) 

Expected mean 

cross pröducts 

Among years 

Y-1 

MCPY 

A-ong groups/years 

G-Y 

MCP^ 

\J 

Among s ires/groups/years 

S_G 

MCPS 

cov" * K cov, 

Among litters within sires n.-S 

MCPI{ 

covw 

a. Phenotypic correlation between 

estimated as follows: 

traíts x and 

(r , .)was p(>n'

25 

where: 

"ott(*y) 

2 

ã: 

"r(x) 

= total covaríance component between traits x and y 

total variance component for trait x 

222 

i'e' oY(*) + oc(*) * ot(*) * 

2 

on 

(*) 

2 

a-. . = total variance cornponent for trait y 

r(y) 

r'e' .2222 

oY(y) * oc(y) * os(y) + on(y) 

The standard error of the phenotypic correlation coeffícient 

(S.E.r ) v¡as estim¡ted as follows: 

p 

S"E.r 

where: n. is the total number of lítters 

b. GeneLic correlation betr¡een traits x and y (Tg(*y)) was 

estimated as follows: 

tc(*y) 

= tots(*y) 

22 

os 

(*) os (y) 

where: 

.ors(*y) = sire componerit of covariance between traits 

xandy 

) 

oõ(*) = sire component of 

variance for the traít x 

2 

oõ(r) = sire component of 

variance for the traít y

lf) 

Standard error of the genetíc correlation (S.n.ra) was calculated 

according to the method described by Robertson (1959) and is 

as follows: 

S.E.r^ 

LJ 

- 

r- (rr,-, ) 2 s.E.-2, . s.E 2 

- '"'h (x) " '"_!{Ð 

T h-h 

xy 

r'¡here : 

S.E.r^(J 

t'= 

-c(>çv) 

= standard error of genetic correlation 


coefficient 

genetic correlation coefficient between traits 

S.E.-?--. = standard error of heritability 

h (x) 

of traÍt x 

S.E."-2r--. = standard error of heritabílity 

h (Y) 

of trait y 

h2 

= heritability estimate of trait x 

2 

h-- 

v 

heritability 

estimate of trait y 

II. Carcass measurements and age 

to market weight 

The analysis of variance and covariance described by Becker 

(L967) was also used for estimation of genetic parameters in carcass 

measurements and age to market weíght. 

wÍthin years and farrowing groups in a 

The analysis was carried out 

nested classifÍcation with un- 

equal numbers of progeny per sire and per dam. The procedures for 

calculating heritabilities, phenotypic and genetic correlations were 

as follows:

¿/ 

l. Heritability estimates - The form of analysis of variance is 

shov¡n in Table 9. 

Table 9. Analysis of variance 


Sum of Mean Expected 

squares square mean 

d.f. (SS) _lMS) square 

Arnong years Y-l SSy 

il:ï::i:::;li:îit,,."." 3-å 33: 

Anong dams/sires/group/ D-S SSO 

years 

Progeny withín darns n..-D SSW 

*s" 

MS G)), 

*S, 

MSo 

MSt 

o"+rroi+rroi 

22 

'IÎ*K1oD 

2 

oI^l 

r,¡here: 

Y : m¡mber of years 

G = number of groups in Y years 

S = nirmber of sires 

.D = number of dams 

n.. = total number of progeny 

EstimaËíon of variance components : 

2 

ol^l 

= MSI^, 

2 

oD 

= MSO - MS" 

\ 

of : *s, - 

(MSw * *, of,> 

\

2B 

vrhere: 

Kt= 

ñ_\ 

L2 .n 

_1ii 

, ri. 

l_ l- 

D_S 

,,2rx2 

- fI .. n_- 

-ii 

ii 

¿ L n. n.. 

K^=l 

't 

s-1 

vt 

inl 

ì{ = fl.. - l_ l_. 

"3 n.. 

s-1 

n- : number of progeny from the ith sire 

l_' 

n-^. = number of progeny from the jth Uæ mâËed to the 

rJ 

.rh 

]. Sare 

n.. = total number of progeny 

Heritability 

estirnates \,,/ere obtained from sire, dam and síre * dam 

components (Falconer, 1960) as follows: 

?2 

n1= o 4 

z-. os 

2 . z 

os*oD*oln, 

4= 

2 

4on 

"3*"3*"?u

29 

Standard errors (S.E.) 

following: 

of heritability 

estimates were obtained from the 

s . E. (n3) 

4 var 

2 

o 

S 

*oD 

ro?> ò 

* 

"lu 

2 

ú 

S 

s.E. (n?r*ol ) 

.r"r ¡ofr¡ 

2) 

-oD*ow 

l)2?? 

= 2 ,l var (or- * var (ofr) + Z cov {o! of) 

os*oD*oIÎ 

where.r"r {of) arra.ra= (ofr) are rhe esrimares of the variance of 

the síre and dam components ïespectively (Becker, Lg67). 

2. Phenotypic and genetic correlaLions. The analysis of covariance 

is given in Table 10. 

Table 10. Analysis of covariance 


d.f. 

Mean cross 

product (MCP) 

Expected mean 

cross produets 

Among years 

Y-1 

MCPY 

Among groups/years 

G-Y 

MCP^G 

Among sires/ groups /years 

S-G 

MCPS 

cov"*K, cov'*K, cov, 

Among dams /sires /groups /yeaïs 

D_S 

MCPD 

cov"*K, cov' 

Anong progeny withîn dams 

n..-D 

MCPw 

covw

30 

Covariance components r,¡ere estimated as follows: 

cov" : MCP" 

covD = MCPD - MCPW 

Kt 

cov^=McPs-MCPD 

uv 

I\^ 

J 

Phenotypic correlation between 

estinated as follows: 

traits x and y (rn.*"¡) r"" 

tp (*y) 

totr(*y) 

or(*) or(y) 

where: 

totr(*y) 

total covariance component betrween traíts x and 

i' e' cov"(*y)+totc(*y)tuots (*y)tuotr(*y)+ 

2 

ot(*) = 

cov__. 

Ir/(xy) 

total variance component for trait 

22222 

i' e' ov 

(*)*ã (*)*r- (*)tuí (*)tui(*) 

? 

oif") = total variance cornponenË for trait y 

i'e' o"c"l*ãry)+o;(v)+oJ (v)tuñcvl 

where: 

totY (*y) 

"otc(*y) 

covariance component of year between traits 


covarlance coaponent of group between traits 

xandy

31 

tots (*v) 

toto(*y) = 

totw(*y) = 

covarr-ance conpoIlent 


covariance cornponent 

covariance component 


of síre between traits 

of dam between traits x and 

of progeny between traits 

2 

ov(*) 

2 

or(*) 

= variance component of year on trait x 

: varíance component of group on irait x 

2 

os 

(*) 

2 

on(r) 

: variance component of 

= variance component of 

sire on traít x 

dam on trait x 

2 

ow(*) 

2 

o"(r) 

2 

or(r) 

2 

or (y) 

2 

oo 

(y) 

= variance c.omporrent of progeny on trait x 

= variance component of year on trait y 

= variance component of group on trait y 

= variance component of sire on trait y 

: variance component of dam on trait y 

2 

o"(y) 

= variance component of progeny on trait y 

The standard error of the phenotypic correlation coefficient. between 

trait.sxandy 

(S. 

E.r ) !ì7as 

p' 

estimated as follo¡¿s: 

S.E.r p 

where: n.. Ís 

It-, 2 

lP 

,l n..-2 

the total number of progeny

1A 

)L 

b. Genetic correlatÍon between 

estimated as: 

traits x and V(ra1*r¡) was 

'c (xv) 

cov^/ 

b (xy) 

s (x) os (y) 

The standard error 

estimated by the method 

of the genetic correlation coefficient was 

outlined by Becker (L967).

-f1 

RESULTS AND DTSCUSSION 

A. 

Reproductive Traits 

I. Means and standard deviations 

Phenotypic means and standard deviations for five reproductive 

traits in different farrowing groups and different years are presented 

in Tables 11 and 12. 

Two-way classification 

of analysis of variance was applied to the 

data. Differences among farrowing groups and among years r¿ere found 

to be significant for all traíts. 

Student-Newman-Keulrs (SllK) 

nultiple range test (Snedecor, L976) was also used to conpare the means 

of three different farrowing groups and different years (Table 1l and 

L2). Mean differences between groups A and B for f ive traits \^7ere 

-1.18, -L.2L, -1.08, -0.L2 anð -0.28 for total number of pigs born, total 

nr:mber of pigs born alive, number of pigs ¡.veaned, average birth weight 

and average weaning weight, respectívely. Íhese differences were all 

staËistically significant (P

34 

Table 11. Means and standard deviatíons of reproductive traits for 

each farrow-ing group for 10 years 

Traít 

n 

Group B 

47r 

Group C 

406 

Total no. of pigs born 

B " 

8012 .0ga 

g .g8!2.24b 

ro.r7!2.40b 

No. of pigs born alive 

B.27t2.OLa 

g .48t2.L6b 

g.o6tz.zob 

No. of pigs weaned 

6.9312.084 

B.OLlz.20b 

7 .ggtz.3Lb 

Ave. birth weight (kg) 

L.28!O.L6a 

1.4010. r8c 

1 .33t0 .19b 

Ave. weaning weight (kg) 

10 .5811 . 604 

a0.86!1.72b 

10.5111. 414 

"b"Diff.rent 

(P

Table i-2. Means and standard devlations of reproductlve trafts for each year 

Trair 1968 

n71 

Toraf no. born 

Total no. born 

altve 

9.82t2.35b" 

9 .28t1.13"b" 

L969 

97 

9.80r2.t3b" 

r970 

111 

9 . 3812 .014b 

g .20t2.13"b" B. g611.99ab 

7977 L972 

i16 133 

9.g3t2.28b" g.2g!2.3oab 

9.10t2.21-ub" 8.8112.154b 

Year 

L973 1974 r97s 

rn ----1Tt- lti 

L97 6 

184 

9.B5tz.39bt 8.97t2.44a 10.4tr2.30b" g.77tz.2sb" 

g.26!2.zzaÈc g.s2!z-33a 9.81t2.35c 

]-977 

190 

g .7 5t2 . h4b' 

g.36t2.27b" g.37t2.3Lb" 

Total no. v¡eaned 6.99!2.lí¿l 

7.BBtz.zrb" 7.r5!z.o7ab 

7.77t2.Lzh" 

7.44!z.ogabc 7.6r!2.30"b" 7.52!z.3lab" B.o8t2.3oc 

7.85t2.37b" 7.g8!2.32c 

Average birch 

welght (kg) L.zglo.Llab 1.38t0.19c 1,35r0.19c 

1.37t0.18c 

1.32t0.18b" 1.32to.t8b" 1.3610.21c 

L.z7!o.Lla 

1.3410.17c 1.3610.18c 

Average weanLng 

weight (kg) 

11.0912.1lc 

11.llt1.6lc 

10.54t1.76"b" 10.6It1.66bc 10.7811.66c 10.9911.28c l-0.63t1.92b" 10.1Bt1.4tab 10.11tl.26" 10.9211.34c 

tb"Dlff.."rrt 

superscrlpE l-ndlcaÈee slgniflcantly 

different between years (p

36 

envíronment in the early stage of embryo development. This stage falls 

in the months of January and February for group A. Krotch (Lg7s) 

studied the effect of ínbreeding of the dam, of the sire and of the 

litter on reproductive perforrnances on Managra gïoup A litters (fron 

Jr:ae-July, L96B to June-July 1973) and group B litters 

(from January- 

February 1969 to January-February L974). He reporred thaÈ the inbreeding 

leve1 increased from 7.r3% in 1968 to r4.gor" in 1973, from 5.9"/" ín 

1968 ro 73.89"Á in 1973 and from 11 .66% ín 1968 to r3.2zz in 1973 for 

group A sire, dem and litters, respectively. The rate of inbreeding 

in group B r¿as less than in group A, changing from 4.L3% ín 1969 to 

7-52% in 1974 for sire and from 4.057" Ln L969 to 7.6L"1 ín L974 for dam, 

and even declined from 11.37" ín 1969 to 9.692 Ln L974 for litters. 

No 

artifieial selection r,{as applied on all five reproductive traíts. Table 

12 indicates diffeïences among yeaïs but no specific trend was observed 

in any of the traits. 

II. Heritability 

Heritability 

estimates 

estimates and their standard errors for five reproductive 

traits are given ín Table 13. These estinates were derived 

from sire components of the analysis of variance. Heritability estirnates 

for three litter size traits are low with high standard errors and are 

not significantly different from zero (p

a1 

Table 13. Estímated heritabilities 

of fÍve reproductive traits 

variance 

and 

their standard errors for each 

from the sire component of 

TraÍt 

.2 hs 

s. E. rnf I 

Total no. of pigs born 

0.07 

a -L2 

Total no. of pigs born alive 

0.02 

0.72 

Total no 

of pigs weaned 

0. 01 

o.L2 

Average bírth weight 

0. 36 

0 .11 

Average weaning weight 

0 .37 

0.11

?o )a 

reproductive traits. 

The high environmental variance and the very lor,r 

additive genetic variance indicates a low response to selection for 

litter 

III. 

sLze traits in swine. 

Phenotypic correlations 

Phenotypic correlations among five reproductive traits are 

presented in Table 14. The correlatíon coefficients among three litter 

síze traits rüere positive and high and generally agreed with Teports 

from other workers. The high positive correlatíons among the litter 

size traits indicate that the dams with larger litter 

would also have larger litter 

síze at weaning. 

síze at birth 

The correlatíon coeffícíent between average birth weighË and 

average weaning weight was 0 " 35 which r¡as lor¿er than the report f rom 

Young et al. (1978) at 0.56 but was close to the value reported from 

Fahrny and Bernard (L972) at 0.42. The relationship betvreen lirter 

sLze (total number born, number born alive ald number weaned) and 

average pig weight (aË birth and aÈ weaning) was negative. This is in 

agreement with the reports fron f'ahmy and Bernaxd (L972) and Young et al. 

(f978). Pigs from smaller litters 

tend to have heavy individual body 

weights at birth and at weaning. Fahny and Bernard (L972) suggesred 

that the negative relationship between litter size and individual píg 

weight is probably due to differences among litters of varying síze 

in competition for maternal nutrients.

Table 14. PhenotypÍca and geneticb correl-atÍons among reproductíve traíts 

TraLt 

Total no. 

born 

No. 

born a1íve 

No. rn¡eaned. 

Average 

birth weight 

Average 

weaning weight 

Total no. born 

0.9210.01 

0.6310 .02 

-0.3410.03 

-0.17t0.03 

No. born alive 

2.30 

0. 7110.02 

-0. 3210.03 

-0.1610.03 

No. weaned 

-2.08 

-6.20 

-0.0610.03 

-0.1210.03 

Average birth weight 

0 . 3010. 46 

L.47 

4,82 

0.3510.03 

Average weaníng weight 

0.9210.09 

L,9L 

0 .52t1 .05 0 .L7 lo .2I 

tPh.rroËypic correlatíons above the díagonal. 

bcenetic correlations below the díagonal. 

(,J 

\o

40 


The genetic correlations among fíve reproductive traits calculated 

from sire conponents of covarianee are given ín Table 14. The 

correlation coeffícienEs of total number born with nuuber born ali-ve 

and number weaned; of number born alive i+ith number weaned, average bírth 

weight and average wealing weight, of number weaned with average birth 

weight are greater than unity. 

A favorable positíve genetic correlation betr¿een total number born 

and average pig weight at birth and at weaníng were found.. The result 

is in agreement with the reports from young et al. (1978). The contradictory 

result betr,¡een genetic and phenotypic correlation on these 

traits could be due to high negative enivronmental covariance components 

(Appendix rr). 

The high negative environmental covariance 

components overcome genetic covarÍance components and result in 

negative total covariance conponents. The competition for maternal 

nutrients could be the reason for thís unfavorable relationship. 

B, Carcass Measurements and Age to Market lÎeight 

I. lleans and standard deviations 

The weighted phenotypic means and standard deviations of carcass 

measurements and age to market weight are shornm ín Table 15 

separately for each sex. The differences between barror¡s and gilts in 

the means of each of ten traits were -1 .02 cm, .27 cmr.19 cm, .26 cm, 

.74 cm, -2.gg .2, -2.L2, -.63"/", -2.03 cn2, and. -13.07 days for 

carcass length, shoulder fat thickness, míd-back fat thickness, 

loin fat thickness, total fat thickness, loin eye area, grade índex,

4L 

Table 15 - Means and standard deviations of carcass measurements and age 

to markeË weight for each sex (adjusted for carcass weight, 

barro¡¿s : 425, gilts : I,030) 

Traits 

Carcass length (cn) 

Shoulder fat 

thickness (cn) 

Mid-back 

thickness (cm) 

Loin fat 

ËhÍckness (cn) 

Total fat 

thickness (cra) 

Difference 

Sex MeantS.D. (barrows-gí1ts) 

M 

F 

M 

F 

M 

F 

M 

F 

M 

F 

76.7\x2.55 

77 .7 3t2.29 

4.3010.51 

4 .0310.50 

2.LLlo.37 

7.92!0.37 

3 .34t0.43 

3 .08t0 .41 

9 .77 !1_ .04 

9.0311.06 

-l .02't* 

o.27xx 

0 " 

19** 

0.26x,\ 

o .7 4xx 

Loin eye ) 

area (cn-) 

Grade index 

"/" Ham weight 

Ham surface" 

area (cm') 

M 28.67!3.54 

F 31 .6613. 87 

M 100. 7812. 90 

F L02.90t2.70 

M 26.38!1.70 

F 27.0L!L.53 

M 

F 

I24.24!L4.77 

L26.27!15.9L 

-2.ggxx 

ôa^¿J 

-0.63** 

-2.03x 

Age to market weíght M 179"15t14.80 

(days) F I92.22!L4.64 -lJ. Q/:c:t 

^"P< . 05 ; ;lJrp< . Qf .

4l 

% lnam weight, ham surface area, age to market weight, respectively. 

Al-1 differences rr'ere statisticalry 

signíficant (p

43 

Table 16. Means and standard deviations of carcass measurements and 

age to market weight traits for each farrowing group 

(adjusted for sex and carcass weíght) 

Trait 

n 

389 

Farrowing group 

625 

44L 

Carcass length (cn) 

77 .24!2.r|b 

7 6 .28!2 .3La 

7 6.53!2.L64 

Shoulder fat 

thickness (cu) 

4.42t0.46b 

4.22!0.484 

4.27!0.464 

Mid-back 

thickness (crq) 

2 .18t0. 3Bc 

2.0810.36b 

2. O3t0 . 364 


thickness (cto) 

3 .33rO.3Bb 

3 .33t0.38b 

3 .28t0 .38a 

Total fat 

thickness (cn) 

9 .9310 " 

91b 

g .6gxo.gla 

g.6oto.g|a 

Loin eye ? 

area (.rn-) 

28 .3813.614 

28.44!3.684 

28 . B3t3 .614 


gg .67 !2 .Bza 

LOO .4L!2.74b 

LO} .2L!2.77b 

% t,am weight 

26 .72!L -6gc 

26 .09t1.5g4 

zø.4stt.4zb 

Hau surface 

area ("r2) 

LzL.O7!r5.224 

725 .45!L4.g6c 

L23.O7tLz.g6b 

Predic ted 

yield (7") 

7o .45!z.3Ba 

7L.L2t2.47c 

70.80t2.20b 

Age to market weight 

(days) 

185 .00114 . B9a 

188 .50t16 . 00b 

191 .14t15 . BBc 

"b"Diff.tent superscripts indicaËe significantly different at p

Table 17. Means and standard devlatlons of carcasg measuì:enents and 

age to market welght Eralts for each year (adJusted for sex and carcass welght) 

Trait 

n 

Carcasg 

length (cn) 

Shoul-der fat 

thickness (crn) 

Mld-back fat 

thlckneee (cn) 

Loln faE 

thlckness (cm) 

Total fat 

lhlckness (cm) 

1471 

298 

7 6 .7 6!2 .46b 

4 .37 lO .48c 

2.0gr0 .3Bc 

3 .4510 . 3Bc 

9 .91jO .99cd 

1q:77 

2t7 

7 6 .7 6!2.06b 

4 .27!O.46ab 

1 .9110 .304 

3 .2810.38b 

g .47!o.B6a 

lq.7i 

250 

7 6.86!2.2rb 

hó 

4 .34!O.46"" 

1.9610.30b 

3 .2510 .3Bb 

9 .58t0. 94ab 

. L974 

220 

7 6 .33!2 .36b 

4.22!0.484 

2.0610.33c 

3 ,33t0.38b 

9.63t0.894b 

I9l 5 

L65 

76.68t1.88b 

4.1710.514 

2.2g!O .3oe 

3.28t0.33b 

9 .73t0. B9l'" 

1976 

202 

7 6 .7 3t2 ,24b 

4.32t0.43b" 

2.36!0 .33f 

3.3310. 36b 

10.0310.97d 

.L97 7 

103 

7 5 .62!2 .3ga 

4.27!0.464 

2. 21t0.30d 

3.1810.364 

9.63t0.97ab 

Loln eye ) 

area (cm-) 

Grade lndex 

Z ham weight 

Ham surface 

a.ea (cm2) 

Pred fc ted 

yleld (Z) 

Age to market 

wefght (days) 

27,48!2.g74 

gg .7 5!3 .r3a 

26.26!L.64b 

125111 .93c 

7o.i,oxz.ogb" 

L84.72!16.LBa 

29,73!3.55c 

100 .3912 .53ab 

25 .94!L.584 

L3L .7 7 !I2 .7 Ie 

7L.8g!2.21d 

Lgo .23tr6.7 4b" 

29 . 0913 .81b" 

100.19!2 . B3ab 

25 .84!L.474 

L25 .g7 !L3 .Ogc 

70.76!2.31,c 

189.78115 . zBb" 

28 .38t3. 68b 

gg .93!2,694 

25 .g2!r.484 

:..2g .32!:16.O6d 

7I .62!2.44d 

189 .49116 .34bc 

27 .35!3.7 4a 

-100.6912.50b 

26.87t1.38c 

109 . 78t10.004 

69 . 6011.894 

184.99112.824 

z9 .03t3. 61b" 

gg .g2t2.704 

26 .9011 .1 3c 

114.17112.13b 

70.1512.37b 

792.82tr6.34c 

29.3513:48c 

100.8312.70b 

27 .g1¿!l .(t6d 

123.13r11.09c 

71 .85!2.55d 

186 .8 2t11 . 7 74b 

abcdef-. -- Dltterent superscrlpt lndicaEes slgnlflcantly 

dlfferent at p

45 

Most of the heritabilities 

derived from the dam components Ìùere 

higher than those from the sire components. The hígher heritabílity 

estimaËes from dem components are possibly due to maternal effects. 

The heritability estim¡¡s for carcass length was hÍgh at 0.62 

2 

(hi*o) and fel1 within 

The herÍtabÍlities 

the range reported from other researchers. 

for three individual fat thickness measuremenËs 

and total back fat thickness were íntermediate and in good agreement 

with values reported by Flock (1970), siers et al. (L912) and 

Roy et a1. (1968) but were considerably lower than the reports from 

SnÍth et al. (L962), Jensen er al. (L967), Anganosa er al. (f969), 

Enfield and Whatley (1961) and Fahmy er at. (f970). 

The heritability 

of ioin eye \"ras .53 and was ín close agreement 

r¿ith the estimates reported by Flock (1970), Jensen et al. (L967), 

Arganosa et al. (1969), smith and Ross (1965), Enfield and LÏhatley 

(1961), Fahmy et al. (1970) and Roy er al. (1968) bur was higher rhan 

the estimete of 0.35 by srníth et al. (1962) and r^ras lower than the 

estimate reported by Siers eË al. (L972). 

The percent ham weight of c.arcass side weight rnras moderately 

heritable and the value estim¡lsd from the presenË study was in agreement 

wíth other reports. 

The herj-tability 

of ham surface area, percent predicted yield and 

age to market weight were 0.41, 0.56 and 0.59, respectively. 

The 

estimatiorsfor these Ëraits were slightly higher than the values reported 

in the literature. 

In conclusion, Ëhe traits of carcass shoulder fat Èhickness, midback 

fat thickness, loin fat thickness and the percenË ham weight were

Table 18. Heritabil-ity estlnates for carcass measurements and age to market weight traits 

Trait 

h3 = 

') 

4o7 5 

-2--- 2 --z or*oO*o" 

.2 h=D 

4"3 

os*oD*olni 

222 

h? = 2k3*ofrl 

^'s+D -T--T- -Z 

oi+oi+ofr 

Carcass length 

Shoulder fat 

thickness 

Mid-back fat 

thickness 


thickness 

Total fat 

thíckness 

Loin eye 

area 


7" ham weight 

Ham surface 

area 

Percent predlcted 

yield 

Age to rnarket 

weíght 

0.8610.15 

0 .3010 .l_2 

0 .1010 . tt 

0 . 30t0.11 

0 .41r0.l_3 

0. t5r0 .13 

0.20!0.L2 

0 . 33!0 .11 

0.3810.12 

0 . 3310 .15 

0 .3910 .13 

0.3910.12 

0.4710.15 

0.57r0.16 

0 .1810 .14 

0 .50r0 .14 

0.9210.16 

0 . 7Br0 .16 

0 .1510. 14 

0 .4310 . 14 

0.7910 .18 

0.7910.15 

0. 62r0 .08 

0. 3910 .07 

0 .33t0 . 07 

0.24x0.07 

0 .4510 .07 

0.5310 .07 

0.4910.07 

0.24!O .07 

0 .4110 .07 

0.5610.08 

0 .5910.08

47 

moderately heritable while carcass length, total fat thickness, loin 

eye area, grade index, ham surface area, percent predicted yield and 

adjusted age to market weight were highly heritable. 

III. 


Phenotypic correlatíons among the eleven traiLs are 

summarized in Table 19. 

Carcass length \,Jas negatively correlated wíth shoulder fal thickness' 

mid-back fât thickness, loin fat thickness, loin and ham surface 

area' and age to market weight, but was positively correlated with carcass 

grade. The correlations betr¿een carcass length and percent ham 

weight and predicted yield were negligible. 

These findings indicate 

that longer pigs should have l-ower back fat, smaller loin eye and ham 

surface, faster growth rate and higher carcass grade index. This 

finding was in good agreement wíth most reports from previous research. 

The relationships among the back fat thickness measurenents were al-l 

positive and the values ranged from 0.32 to 0.53. similar results 

have also been reporred by Smirh et al. (Lg6Z). 

Loin eye area !/as negatively correlated with all three back fat 

thickness measurements, but was positively correlated wÍth grade, percent 

ham weight and ham surface area and highly positively related to 

percent predicted yield. 

The association between loin eye area and 

age to market weight was positive but low in magnitude. The phenotypic 

correlation coeffÍcients between loin eye area and back fat 

thickness, percent predicted yield and age to market weight reported. 

from the present study were fairly 

similar to the reports from Smith 

et al. (1962), smith and Ross (1965), Jensen er ar. (1967), Arganosa

Table 19. 

PhenoLyplc correlatÍons among nlne carcass measurements and age to narket welghL tralts 

Tralt 


Shoulder faE 

Mid-back far 

Loln fat 

Total fac 

Loln eye area 

Grade 

Z Han welghr 

Ham surface 

area 

% Predicted 

yle1d 

Shoulder 

fat 

-0.1110.03 

Back faC Loln fat 

-0.1610.03 -0.1610.03 

o.32!0 .02 0 .5310 .02 

0.3910.02 

Loln eye 

Total fat area 

-0,18t0 .03 -0.1310.03 

0. 79i0.02 -0.1810.03 

0 .6810.02 -0. 1310.03 

0.8110 .02 -0. 20J0.03 

_0.22r0.03 

Carcas s 

lndex 

0.1510 .03 

-0 .7 6!0 .02 

-0 .35r0.02 

-0 .7 4!0 .o2 

-0.8110.02 

0 . 1910 .03 

"/. Ham 

welgh t 

-0 . 0510 .03 

-0.1310 .03 

0 .0110 . 03 

-0.1910.03 

-0 . 1310 .03 

0. 1 2t0 .03 

0.1510.03 

Ham surface 

ar ea 

-0.1410.03 

-0 .1510.03 

-0.3610 .02 

-0,1210.03 

-0.2610.03 

0.3010.03 

0.1410 .03 

-0. 2310 .03 

Z Predicted 

yield 

-0.0610 .03 

-0.5310.02 

-0.5310.02 

-0.5310.02 

-0 .6910. 02 

0.5110.02 

0.52!0.O2 

0 .0810.03 

0.75r0.02 

Age 

-0.14r0.03 

-0.1010 .0 3 

-0.22t0.03 

-0.1110.03 

-0.19r0 .03 

0.0910.03 

0.03r0.03 

0.01r0.03 

0 .1510 .03 

0.21:0.03 

.Þ. 

co

,o 

AJ 

et 41. (L969), Roy er al. (1968), Enfield and \,,rharley (1961), Fahmy 

and Bernard (f970) and Swiger er al. (1979). 

As expected, the correlations between grade index and back fat 

thickness measurements v/eïe highly negative which agreed r¡ith the basic 

principle of the Canadian market hog index system. The relationships 

between grade index and percent ham rveight, ham surface area and percent 

predicted yield r¡/ere positive. 

The carcasses with lower shoulder 

or loin fat thickness r¿ill have higheï percent ham weight. Ham surface 

area !)as negatively correlated i^rith three back fat thickness measurements 

and percent ham weighr, but was highly posÍtively correlated 

with percent predícted yield. 

The negative association between age to market weight and the 

three back fat measureinents indicated that faster groi+ing pigs were 

somer,¡hat fatter. 

This finding corresponds to the result described 

earlier where faster growing pigs in group A had higher back fat 

measltLements and ¡^rere lower in carcass grade index in conseqrlence. The 

positive correlatíons betv¡een age to market rveight and h:m surface area 

and percent predicted yield implied that pígs requiring the longer time 

to reach market weight would have larger hem surface area and higher 

percent predicted yíeld in carcasses. 


Genetic correlations among the 

components of variance and covaríance, 

traits, calculated from síre 

are presented in Table 20. 

The genetic correlaËions among 

eleven traiLs behaved si_ur_ilarly

Table 20. Genetic correlatlons among carc¿rss measurement.s and age to rnarket welght 

Tral-t 

Shoulder 

faE 

Back fat. 

Loln faË 

Total fat. 

Loin eye 

area 

Grade 

lndex 

Z Ham 

wefgh E 

Ham surface 

area 

Z Predlcted 

y1eld 

Àge 


Shoulder fat 

Mfd-back fat 

Loln fat 

Tolal fat 

Loin eye area 

Grade lndex 

Z Ham welght 

Han surface 

area 

Z Predlcred 

yleld 

-0.17r0 .18 

-0.0110.32 -0.24!0.L7 

]. 40r0.67 0.5610.18 

L.42!0.58 

-0.1410.16 -7.07!o.46 

0.8810.06 0.1810.47 

1 .5010. 53 -0.0110. 65 

0 .9210.06 0 .5110.55 

0.2L!0 .42 

O.22!O.22 

-1 . 0410 .13 

-1 .5510 .71 

-1 .3010.21 

-1. 2510.18 

-1 .0210. 91 

0 ,0210 .1 7 

-0.3610.24 

-0.7610.4 9 

-0.20!o.24 

-0. 3510 .21 

-0.19r0.42 

0.6210. 30 

-0. 6010 .16 

-0.49!O.24 

-0.6110.48 

-0.1410. 24 

-0.4610.20 

0.64t0.32 

o.L2!0 .32 

0 .1610. 23 

-0.43t0. 19 

-0.86t0.14 

-1.3010.53 

-0 .5510.18 

-0.8510 .10 

0.2810.36 

0. 78t0.20 

0.3010. 24 

0.8310.10 

-0 . 27r0 .16 

-0.6110.28 

-0. 9610 . 5B 

-0.18r0.19 

-0.57!0,22 

0.1210.38 

0.79t0.4? 

0.1310.24 

0.3310.23 

0.5510.25 

L¡I 

O

51 

to phenotypic correlations in most cases although the genetic correlations 

were higher. Several values outsíde the theoretical range (rG , 1 o, 

tG ' - 1) were found, i.e. mid-back fat with shoulder fat, loin fat 

and total fat, carcass length with loin eye area, grade índex with three 

back faË thickness measurenents and total fat thickness and loin eye 

area' mid-back fat with percent predÍcted yíeld. 

coefficients are high in standard error. 

Most genetic 

The back fat thÍckness measurements at three different points were 

highly positively correlated with each orher. A si_milar finding has 

been reported by smith et a1. (L962). selection for 1or¿er back faË 

thickness at one location will reduce thickness at other areas and 

average back fat. 

Carcass length had moderately negative correlations with shoulder 

fat, loÍn faÈ, total fat and age to markeË weight. The correlations 

betr¿een carcass length and ham surface area and percent predicted yield 

were highly negarive. snith er a1. (Lg62), smith and Ross (1965), 

Jensen et al. (1967), Flock (L970), siers and Thomson (L972), Enfield 

and IÎhatley (1961) and Roy eÈ a1. (196g) also showed that negarive 

correlatÍons existed between carcass length and carcass back fat and 

percent lean cuts. Loin eye area was positively correlated Ì,¡ith loin 

fat which suggested that selection for lower back fat at loin would 

reduce loin eye area simultaneously. This result is not in agreement 

wÍth reports from previ-ous research. 

Percent han weight \474s negatively correlated with a1l three back 

fat thickness measurements and 1oÍn eye area and the values ranged from 

medium to hÍgh, but it was positively correlated with ham surface area,

52 

percent predicted yield, grade and age to r¡arket weíght, the coefficients 

ranged from low to hígh. 

The relationships between ham sur_ 

face and shoulder fat, mid-back fat and total back fat thickness measure* 

mentswere highly negative' whíle the relationshÍp betr¿een ham surface 

area and percent predicted yield was highly positive which suggested 

that selection for larger hau surface area would. increase percent predicred 

yield. 

The high negatíve correlations between percent predicted yield and 

back fat thíckness measurernents indicat.ed that selection for lower 

back fat thiekness would signifícantly increase the percent predicted 

yÍeld. selection for larger roin eye area, percent ham weight, ham 

surface area or grade index should lead to an increase in peïcent predicted 

yÍeld. 

The correlations betr¿een age to markeÈ weÍght and backfat thíckness 

measurements rùere highly negative except for loin fat which Índicated 

that sel-ection for fasL growth rate would Íncrease back fat thickness 

and decrease carcass grade index in consequence. The relationships 

between age Lo market weight and grade index, ham surface area and percent 

predícted yield were positive and high. 

These findings suggested 

that selectíon for lower back fat or hÍgher grade index or srnaller ham 

surface area or higher percent predicted yield would tend to increase 

age to market weight unless the traits \¡/ere combined in a selectÍon 

i-ndex.

53 

SI]MMARY AND CONCLUSION 

Data from L,268 first 

parity gilts and from r,455 rnarket pigs of 

the Managra breed were analyzed to estimate phenotypic and. genetic 

parameLers for five reproductive trairs, 

ten carcass measurements and 

age at 90 kg live weight. 

Heritability 

estimates v¡ere calculated from Ëhe sire coûponent 

of variance. Three litter 

size traits including total number of pigs 

born, nurnber of pigs born alive and number of pigs weaned had lor¿ heritabilities 

i¿hich indicate that litt1e response would be expected from 

selection. 

Average birth weÍght and weaning weíght had moderate heritabilities 

which reveals that about 40"Á of the differences in these traits 

r'¡ere attributable to geneLic causes and r¡ould be expected to be transruitted 

to offspring from parents. Phenotypic correlations among three 

litter 

size traits were hÍgh1y positíve and generally agreed with the 

results from previous research. Average birth weight was moderately 

correlated phenotypically with average weaning weÍght. phenotypic correlations 

between litter 

sÍze tralts and average pig weight at birth and 

weaning were moderately negative except the correlation between 

nr:mber weaned and average pig birth weight. Genetic correlations between 

total number born and average birth weight and average r+eaning weight 

were 0.3010.46 and O.92t0.A9, respectively. 

Genetíc correlations between 

average pig weaning weÍght and nr-rmber of pÍgs weaned and average birth 

weight were 0.52!L.05 and O.L7XO.2L, respectively. 

Heri'tability 

estimates for carcass neasurements and age at 90 kg 

live weÍght T/¡ere anaLyzed by hierarchÍcal .analysis 

of varíance. Three 

carcass back fat thícknesses (maximum shoulder fat, minimum mid-back

54 

fat and loin fat), total back fat thíckness, grade index, T" ]'am weight 

and ham surface area \¡/ere moderaËely heritable. The heritabilities of 

carcass length, loin eye area, "/" preð.icted yield and age at 90 kg live 

weight were high and ranged from 0.53-0.62. Moderate and high response 

would be expected from selection of those traits. 

phenotypic and 

genetic correlations vrere calculated from analysis of covariance. 

Phenotypic correlations of carcass length with three back fat thicknesses, 

loj-n eye area, ham surface area and age at 90 kg live weÍght 

r{ere negatÍve but smaIl. The phenotypic correlations among three back 

faÈ thicknesses were positÍve and intermediate. Loin eye area \¡/as 

negatively correlated i¡Íth three back fat thicknesses but was positively 

correlated with grade index, T" ]r,am weight, ham surface area and % predicted 

yield- 

Grade index was highly negatively correlated r¿ith three 

back fat thicknesses and was positively correlated r¿ith Z :ham weíght, 

ham surface area and % predicted yierd. 

Ham surface area 'sas 

negatively 

correlated ¡¿ith back fat thÍcknesses and "/" :ham weÍghË but was 

positively correlated with Z predicted yíeld. 


of age at 90 kg live weight r¿ith three back fat thicknesses Trere 

negative but sroall. The relationship of age at 90 kg rive r^¡eight \^/ith 

ham surface area and "/" predicted yÍe1d was positive. 

Genetic correlatíons 

among carcass measurement and age at ng ut live weighÈ 

generally behaved siurilarly to the phenotypíc correlations but v¡ere 

higher in rnagnÍtude. Most of the genetic correlations had hÍgh standard 

errors. 

In conclusion, most carcass traÍts \,Jere 

each other whÍch indicates that selection for 

favorabl-y correlated with 

one carcass trait would

55 

also improve Ëhe others where several carcass traits \,rere considered 

simultaneously in a breeding program. The relationshipsbeiween growth 

rate i.e. age at 90 kg líve weight and carcass traits r¿ere unfavorable.

56 

LITERATJRE CITED 

Arganosa, V.G., I.T. Orntvedt and L.E. Walters. 

genetypic parameters of some carcass traits 

An. Sci. 28:I6B-L14. 

L969. Phenorypic and 

in swine. J. of 

Baik, D.H., Y.K. Park, B.K, Ohh and S.iÎ. Han. Ig74. Heritabilities 

repeatabllÍties, and geneiic correlations among litter size, 

1Ítter weight, and gestaLion length Ín swine. Korean J. of An. 

Sci. L6(2):L52-I57 . 

Becker, W.A. L967. Manual of procedures in 

(2nd ed.), I^lashfngton State University 

University, pullman, I,Iashington. 

quantitative geneties 

Press, InJashington State 

Bereskin, 8., c.E. shelby and L.N. Hazel. Lg7L. carcass traits of 

purebred Duroc and yorkshires and their crosses. J. of An. 

Sci. 32:4L3-4L9. 

Boylan, w.J., trrr.E. Remper and R.E. comstock. Lg6r. Heritability 

litter size in swine. J. of An. ScÍ. 20:566_568. 

of 

Enfield, F.D. and J-4. Idhatley, Jr. 1961. Heritability of carcass 

length' carcass backfat thíckness and loin lean area in swíne. 

J. of An. Sei. 20:63I-634. 

Edwards, R.L. and r.T. ûntvedt. Lg7L. Genetic anarysÍs of a sr¿ine 

populatÍon. rr. Estimates of population paraÐeters. J. of An. 

Sci. 32:185-190. 

Fahmy, M.H. and C.S. Bernard. Ig7O. 

score on the genetic improvement 

Can. J. of An. Sci. 50:585-592. 

Effect of selectíon for carcass 

of its components in swine. 

Fahny, M.H. and C.S. Bernard. Lg7O. 

pre- and post-weaning weights and 

An. Sci. 50:593-599. 

Genetic and phenotypic study of 

gains in sr¿ine. Can. J. of 

Fahmy, M.H. and c.s. Bernard. Lg7z. rnterrelations between some 

reproductive traïts in swine. can. J. of An. sci. 52239-45. 

Fahny, M"H. and c.s. Bernard. Lg72. Reproductive performance 

gilts 

of 

from lines selected for feed utilízatíon and carcass score. 

Can. J. An. Sci. 52:267_27L. 

Falconer, D.s. 1960. rntroduetion to quantitative genetics. Eighth 

Printing, Ronald press, New.york.

57 

Flock, D.K. 1970. Genetic parameters of German Landrace pigs estimated 

fron different relationships. J. of An, Sci. 30 :839-843. 

Huntsberger, D.V. and p. Billingsley. 

inference (4ttr ed.), pp. 2j4_277. 

Lg77 " Elements of 

s tat is tical 

Jensen, P., H.B. craig and O.tr^r. Robison. 1967. phenotypic and genetÍc 

associations among carcass traits of swíne. J. of An, scí. 

26:I252-L260 . 

Krotch, K.M. 1975 - The effects of sire and of inbreeding of the dam and 

of the litter on pre\^Teaning traits in a closed breed of si¿ine. 

M.Sc. Thesis, University of. l"fanitoba. 

Parker, R-J. 197L. Development of the Managra - A new breed of swine. 

Dept. of Animal science, university of r"r¿nitoba (unpublished 

paper) . 

Revelle, T.J. and o.IÎ. Robison. L973. An ex,olanation for the 1ow 

heritability of litter síze in swine. J. of An. Sci.37:668-615. 

Robertson, A. L959. The sampling variance of the genetic correlation 

coefficient. Biometrics. L5:469-485. 

Roy, G.L., iÎ .J. Boylan and M,E. Sea1e. 1968. Estirnates of genetic 

correlat.ions among certain carcass and performance traits in 

swine. Can. J. of An. Sci. 48:1-6. 

siers, D.G. and G.M. Thomson. Lglz. Heritabilities and genetic correlations 

of carcass and growth traits in swine. J. An. scÍ. 

35 : 311-316. 

s'ith, c., J.I^l .8. King and N. Gilbert. L962. Genetic parameters of 

British Large lÎhite bacon pigs. An. prod. 4zLZB-L43. 

s*ith, c. and G.J.s. Ross. 1965. Genetíc parameters of British 

Landrace bacon pigs. An. prod.7:29I-30L. 

snedecor, G.w. and i,J.G. cochran. Lg76. statistical Merhods. 

sixth Edition. The roi¿a state uníversity press, Ames, rowa. 

stockhausen, c.w.F. and LrI.J. Boylan. L966. Heritability and genetic 

correlation estimates in a ne\¡r breed of swine. can. J. of An. 

Sci. 46:21L-2I6.' 

strang, G-s. and J.I,I.B. King. Lg7o. LiLter productivity in Large 

hlhite pigs. An. Prod. L2(Z) 2235-243.

58 

swiger, L.A. ' 

G.A. rsrer and iÎ .R. Harvey. rg7g. postweaning genetic 

parâmeters and indexes for swine. J. An. sci. 48:1096-1100. 

Urban, Lï.E., Jr., C.E. Shelby, A.B. Chapman, J.A. irì.hatley, Jr. and 

V'A' Garwood. L966. Genetíc and environmental r"på"t" of litter 

size in swine" J. of Arr. Sci. 25:1148_1153. 

Young, L.D., R.A. pumfrey, p.J. Cunningham and D.R. Zímmerman. L978. 

HerÍtabilities and genetic and phenotypic correlations for preprinciple 

components. 

breeding traits, reproductive traits and 

J. of Än. Sci. 46:937-949.

APPENDIX 

s9

Appendix r. Analysis of variance of reproductive traits 

Mean squares 

Source of 

varíation 

Year 

Group/yr. 

Sire/group/yr. 

LitËer/si re / gr o:up / yr, 

D. F. 

9 

20 

4LB 

B1_6 

Total no. 

born 

l_7 . 83 

29 .47 

5 .08 

4.84 

No. born 

alive 

No. 

weaned 

15 .67 13.58 

30 .23 26.24 

4.58 4 .69 

4.53 4.68 

Ave. 

birth wt. 

0 .18 

0 .18 

0"04 

0 .03 

Ave. 

wn. wt" 

l-6.53 

10 .71 

2"75 

2.L4 

2 

ú 

S 

0.084 

0 .018 0 .006 

0.003 

0.22 

2 

6 "w 

4.84 

4.53 

4.68 

0 .03 

2.r4 

Or 

O

Appendix rr. Anal-ysis of covarÍance of reproducti_ve traits 

Mean cross products 


covariance 

Year 

GrouB/yr. 

D.F. 

9 

20 

Total no. 

born and 

no. born 

alÍve 

15.97 

29.L5 

Total- no. 


no. weaned 

I .70 

23.84 

Total no. 


ave. bírth 

wt. 

-L.L2 

0.74 

Total no. 


ave .h7n.I,It. 

-3 .48 

-3.43 

No. born 

alive and 

no. weaned 

9 .13 

25.23 

Sire/group/yr . 

Litter/sire/ 

group/yr 

Cov, 

418 

816 

4.47 

4.22 

0 .09 

2.85 

2.98 

-0.05 

-0. l-5 

-0 .16 

0.005 

-0.34 

-0. 6B 

0.I2 

3.09 

3.27 

-0 .07 

Cov" 

4.22 

2.98 

-0.16 

-0.68 

3.27 

o\ 

F

Appendix II (Contínued) 



covariance 

Year 

Group/yr. 

Sire/grouplyr. 

Litter/síre/ 

gtoupf y'r. 

Cov, 

D.F. 

9 

20 

418 

816 

No. born 

alÍve and 

ave.bírth 

vüt. 

-r.04 

0. 70 

-0. 13 

-0.16 

0. 01 

No. born 

alive and 

ave " T.{Tr. 

I^rt . 

-4.L6 

-4.53 

-0.27 

-0.61 

0.L2 

No. weaned 

and ave. 

birth rn¡t. 

-0.03 

0. 84 

-0 .002 

-0.06 

0.02 

No. weaned 

and ave. 

wn. wt. 

-4.60 

_t 70 

L.l ) 

-0.34 

-0. 39 

0 .02 

Ave. birth 

wt. and 

aVe "vm.r,¡t. 

0.39 

0.68 

0 .10 

0.09 

0 .005 

Cov, 

-0. 16 

-0 .61 

-0.06 

-0. 39 

0 .09 

o\ 

N)

Appendlx rrr' 

Ànalysfs of varlance of carcass neasurements and age to harket wefght 


varLaÈion 

Year 

Group/year 

Slre/group/yr. 

Da¡/efre/group/ 

D. F. 

6 

13 

269 

yr. 368 

Progeny/dan/ 

elre/group/ 

yr. 798 

2 

os 

) 

oD 

Carcaeg 

length 

3.901 

5.055 

L.497 

o.676 

0.523 

0.t62 

0.074 

Shoulder 

faE 

0.157 

0.277 

0 .046 

0.033 

0.o25 

0 .002 

0.004 

Mfd-back 

faE 

Loln 

fat 

0.887 0.254 

0.153 0.095 

0.020 0.028 

0.018 0.020 

0.013 0.o18 

0.0004 0.0016 

0.0022 0.0010 

Total 

fat 

Mean gquares 

Loln eye 

area 

L.263 4.283 

0.932 2.105 

0.203 0.418 

0.132 0.344 

0.099 0.209 

0.013 0.011 

0 .016 0.066 

Grade 

lndex 

PercenÈ 

hau wt. 

28.6]-2 85.599 

42.438 30.891 

I0.822 2.649 

8.571 1.840 

5.594 t.694 

0.360 0.159 

t.443 0.071 

Ham eurface 

area 

295.333 

60.943 

5.192 

3.481 

2.7L8 

0.323 

0.370 

Percerrt 

pred.yfeld Ape 

146.259 1869.03 

55.901 2134.2r 

7.442 380.84 

5.246 255.15 

3.355 162.02 

0.385 22.56L 

0.91 7 45 .L40 

ot.¡ 

0.523 

0.025 

0.0130 0.0183 

0.099 0.209 

5.594 1.694 

2.7L8 

3.355 162.020 

o\ 

(¡J

Appendlx IV. Analysls of covarlance of carcass neasurements and age to market welght 



covarlance 

Yeãr 

Group/yr. 

SIre/ group/yr. 

D. F. 

Darn/ slre / group / 

yr. 368 

6 

13 

269 

ProEeny / dan/ 

eLre/ Eroupf 

yr. 798 



shoulder fat 

0.379 

0.580 

-0.048 

-0 "029 

-0.017 



m1d-back fat 

-0.454 

0.44'J. 

-0.030 

-0 .0 28 

-0.019 



1o1n fat 

0.381 

0.118 

-0 .03s 

-0 . 017 

-0.024 



total fat 

0.333 

T.T26 

-0.109 

-0.076 

-0 .060 

Carcass lengLh 


loln eye area 

-0.475 

-1. 386 

-0.223 

-0 .006 

-0 .011 

Cov^ò 

Cov- l) 

Cov,, 

-0 .00 3 

-0 .006 

-0.017 

-0 .0001 

-0.0046 

-0.0l-89 

-0.0040 

0.0030 

-0.0237 

-0.0062 

-0.0076 

-0 .0602 

-0.Ot |tt 

0.0021 

-0.0107 

. Con t lnued 

o¡\ 

¡-

Appendlx IV (Conrinued) 



covarlance 

D. F. 

Carcass l-ength 


grade lndex 



% ham ¡¿t. 


and ham 

surface area 

Carcass l.ength 


% pred. yleld 



agg__ 

Year 

6 

-3.744 

-rt.027 

-1.948 

-tr.202 

B. 180 

Group/yr. 

L3 

-6 .090 

4.265 

-I2.725 

-11.866 

-82.937 


269 

0.797 

-0 .085 

-0.759 

-0 .389 

-4.895 

Daml eLrel group/yr. 

368 

0.507 

-0.080 

-0.071 

0.133 

-1.993 

Progeny/darn ls'Ixel 

group I yr . 

798 

0.313 

-0.036 

0.002 

0,r29 

0.2L6 

Covr' 

0.053 

0 .000 3 

-0.1382 

-0.1069 

-o.522 

Covo 

0.094 

-0.0213 

-0.0354 

0.0019 

-1.071 

Cov, 

0.313 

-0.03s9 

0.0021 

o.1292 

o.2t6 

cr\ 

Ln

Appendlx IV (Contlnued) 

Mean cross rrroducts 


covariance 

Year 

Group/yr. 


Dam/ eíre / group /yr . 

Progeny/dam / sLre/ 

group/yr. 

Cov, 

D. F. 

6 

13 

269 

368 

798 

Shoui.der fat 


mld-back fat 

-0.080 

0.077 

0 .016 

0.009 

0.006 

0.0013 

Shoulder fat 


loin fat 

0.113 

0 .097 

0.021 

0 .015 

0 .010 

0.0011 

Shoulder fac 


toEal faE 

0.182 

0.430 

0 ,082 

0 .0s5 

0.039 

0.0049 

Shoulder fat 

and loin 

eye area 

-0.030 

0.028 

-0.032 

-0.032 

-0.009 

0 .0009 

Shoulder fat 


grade index 

-1. 386 

-3.182 

-0,560 

-0. 395 

-0.290 

-0.0301 

CovO 

0 .0016 

0.0024 

0.0077 

-0.0114 

-0.050 7 

Cov" 

0.0056 

0.0102 

0.0393 

-0.0088 

-0.2903 

o. 

cl\

Appendlx IV (Conrlnued) 

Mean cross Droducts 


covarlance 

Year 

Group/yr. 


Dam/ sfte/ group /yr . 

Progeny/dan I strel 

gxoup /yr . 

Cov, 

D. F. 

6 

13 

269 

368 

798 

Shoulder fat 


Z ham wt. 

-0.953 

0.489 

-0.088 

-0.049 

-0 .019 

-0.0069 

Shoulder fat 


gurface area 

7 .443 

-o.644 

-0.128 

-0 .060 

-0.049 

-0.0135 

Shoulder fat 

and Z 

pred, vle1d 

-1 .041 

-t.3r2 

-0. 388 

-0.247 

-0.160 

-o.0257 

Shoulder fat 


åge 

-0.416 

-9.79r 

-0.631 

0.024 

-0.180 

-0. 1403 

Mld-back far 


lofn fat 

0.005 

0.044 

0.014 

0.009 

0.006 

0.0011 

CovO 

Cov* 

-0.0146 

-0.0190 

-0.0053 

-0.0492 

-o.0423 

-0 .1600 

0.0991 

-0.1801 

0.0013 

0 .0060 

Con t lnu ed 

cl' 

!


Mean ctoss products 


covarlance 

Year 

Group/yr. 

SLre/ Erorplyr . 

Dam/ eLre/ group /yr. 

. Progeny/dar¡.l she/ 

group/yr. 

Cov, 

Cov' 

D.F. 

6 

13 

269 

368 

798 

Mld-back fac 


total faË 

0.77 4 

0.273 

0 .050 

0.032 

0.024 

0.0033 

0 .0039 

trfld-back fat 

and loln 

eve area 

-0.658 

-0.260 

-0.009 

-0.008 

-0.002 

-0 . 0000 3 

-0.0027 

Mld-back far 


prade lndex 

0.299 

-0.7 44 

-0.251 

-0.153 

-0.093 

-0.018 

-o.029 

I'fld-back far 


Z ha¡o r¿È, 

6. 785 

0.319 

-0.065 

-0.034 

-0.022 

-0.0058 

-0.005 7 

Mld-back fat 


surface area 

-I4.387 

-I.9I7 

-0.065 

-0.031 

-0 .025 

-0.0067 

-0 .0032 

Cov" 

o.0243 

-0.0022 

-0.093 

-0.0224 

-0 .0248 

o\ 

co




covariance 

Year 

Group /yr. 

Sire/group/yr. 

Daml elrel group/yr. 

Progeny/darn /al:el 

group/yr. 

Cov, 

D. P. 

6 

13 

269 

368 

798 

Mld-back fat 


% pred.yLeLð, 

-7.109 

-2.386 

-0.22L 

-0.138 

-0.096 

-0 .016 

Mld-back fat 


age 

-0. 705 

-9.653 

-0.683 

-0.274 

-0.41-1 

-0 .088 

Loln fat 


total fat 

0.359 

0. 239 

0 .065 

0.043 

0.034 

0.0042 




-0.67L 

-0.079 

-0.019 

-0.026 

-0,005 

0.0021 

Loln fat 


Erade. lndex 

-2.259 

-t .339 

-0 .452 

-0.291 

-0.239 

-0.0309 

CovO 

-0.020 

0.066 

0.0042 

-0 .0100 

-0.0254 

Cov, 

-0.096 

-0 .411 

0.0343 

-0.0054 

-0.2385 

. Cont{nrrecl 

o\

Appendlx IV (Conrtnued) 

Mean crosg producÈs 


covarlânce 

Year 

Group/yr. 

Slre/g¡sup/y¡. 

Dam/ el¡e/group/yr. 

Progeny/dam / eLre/ 

group/yr. 

Cov, 

D.F. 

6 

13 

269 

368 

798 

Loin far 


Z han wt. 

-T.292 

-0.120 

-0 .07 4 

-0.054 

-0.020 

-0 .003 



surface area 

o.776 

0.165 

-0.07 4 

-0.055 

-0 .031 

-0.003 

Loln fat 

and 7" 

pred, y1e1d 

-2.L04 

-0.719 

-0.278 

-0.201 

-0.130 

-0.013 

Loln fat 


aPe 

-8.803 

-3.551 

-0. 250 

-0.103 

-0.201 

-0 .033 

ToEal fat 

and 1o1n 

eve area 

-7.228 

-0.345 

-0.062 

-0.066 

-0 .016 

0.003 

CovO 

Cov" 

-0.016 

-0 .020 

-0 .012 

-0 .031 

-0.034 

-0.130 

0.048 

-0.201 

-0.024 

-0.016 

Contlnued 

\.1 

O

Âppendix IV (Continued) 

Mea4 cross products 


covarfance 

Year 

Group/yr. 

SLre/ grç¡p/y¡. 

Dam/sfte/ Eroup /yr . 

Progeny/dam/s 1re / 

group /yr . 

Cov, 

CovO 

Cov" 

D. F. 

6 

13 

269 

368 

798 

Total fat 


grade lndex 

-3. 341 

-5.505 

-L.282 

-0.825 

-0.618 

-0 .0 86 

-0 .100 

-0.618 

ToEal fat 

and, 7" 

ham ¡+t. 

Toral fat 

and har¡ 

surface area 

4 .116 _11 .409 

0, 868 _2,505 

-0.227 _o .298 

-0.137 _0.t42 

-0.058 _0 .098 

-0.016 -0 .030 

-0.038 _o .022 

-0.058 _0.098 

Total fat 

and 7. 

pred. yleld 

-9.586 

-4.496 

-0 .9l.B 

-0.589 

-0. 387 

-0 .060 

-0.098 

-0.387 

Total fat 


aEe 

-7 .064 

-)1 101 

-I .75tl 

-0.455 

-0 .81 7 

-0.276 

0.175 

-0.817

Appendlx fV (Concinued) 



covarlance 

D.F, 



grade lndex 

Loln eye area 


% ham q't. 


and han 

su¡face area 

Loln eye area 

anð "l 

pred. yield 

Loln eye area 


age 

Year 

6 

3.043 

-1.815 

14.011 

76.307 

7L.6tL 

Group/yr. 

13 

-0 .L7 4 

1.339 

4.3L2 

5 .592 

7t'raA 

SLre/ gtoup/yr. 

269 

0.337 

0.167 

0. 575 

0.957 

O.B89 

Dam/ sLre/ group /yr . 

368 

0.576 

0.184 

0 .360 

o.796 

0.497 

Progeny/dam / s1-re/ 

group/yr. 

798 

0.134 

0.045 

0.150 

0.331 

-0.117 

Covr' 

-0.063 

-0.008 

0.037 

0.018 

0 .060 

Cov' 

0.2r4 

0.067 

0.102 

0.225 

0.298 

Cov" 

0.l_34 

0.045 

0.150 

0. 331 

-0.117 

. Contlnuecl 

! l.J

Appendix IV (Conctnued) 

Mean crosà products 


covarlance 

Year 

Group/yr. 

SLre/ group/yr. 

Dan/ elre/ group/yr , 

Progeny/dan /el¡e/ 

group /yr. 

Cov, 

D. F. 

6 

13 

269 

368 

198 

Grade lndex 

and Z ham 

wefght 

21.545 

-8.509 

r.654 

0.830 

0.249 

0.149 

Grade lndex 

and ham surface 

area 

Grade lndex 

and Z pred. 

yleld 

-22.901 8.823 

6.578 14.720 

r.647 5,633 

1.336 3.951 

0.595 2.384 

0.039 0.29L 

Grade lndex 

and'age 

-I8.292 

86.524 

6.24L 

-4 .001 

0.610 

2.239 

Z Ham welght 


surface area 

-L02.382 

-22.326 

o.284 

0.039 

-0.376 

0.037 

CovO 

0.281 

0.359 0.760 

-2.234 

0. 201 

Cov-- 

0.249 

0.s95 2.384 

0.6r 0 

-0.376 

. ContLnued 

! 

tt

Àppendlx IV (Contlnued) 



covarlance 

D.F. 

% Ham welght 

and % 

pred. yleld 

% Ham welght 


age 

Ham surface 

area and Z 

pred. yleld 

Ham surface 

area and 

age 

7. Pred. yleld 


age 

Year 

Group/yr. 

SLre/gtoup/yr. 

Dam/ s|re/ group/yr, 

Progeny/darn /sl:e/ 

group/yr. 

6 

13 

269 

368 

798 

-28.477 

-L6.435 

T.347 

0.873 

0. 250 

-7L664 

-25.617 

r.922 

0.643 

0 .443 

171.524 

50.019 

4.72L 

3.L30 

2.L72 

84.980 

247 .27_1 

7.053 

2 .600 

1.839 

168 .7 2r 

257 .900 

Lr.292 

3. 366 

3.555 

coys 

0 .075 

0.254 

o.293 

0.884 

r.622 

Cov' 

0,302 

0.097 

0 .464 

0. 367 

-0.092 

Cov* 

0.250 

0 .443 

2.77 2 

1.839 

3.555 

!

75 

Appendix V. Table of differentials 

for carcass grade índex 

Carcass weight (lb) 

Backfat in. 90 

L24 

l-25 

l-29 

130 

r39 

L40 150 

r49 159 

160 L70 

769 180 

181 

195 

796 Ridgand 

ling 

over 

- -1.9 

2.0-2.I 

2.2-2.3 

2.4-2.5 

B7 

B7 

B7 

87 

105 

103 

L02 

100 

109 110 

LO7 109 

105 707 

103 10s 

LL2 IL2 

110 LLz 

109 110 

r07 109 

LL2 

LL2 

110 

109 

9L 

9I 

91 

9T 

85 

85 

85 

B5 

67 

67 

67 

67 

2.6-2 "7 

B7 

9B 

L02 103 

r05 L07 

L07 

9L 

85 

67 

)Q_10 

3.0-3.1 

87 

B7 

97 

95 

100 L02 

98 100 

103 105 

LOz 103 

105 

103 

9T 

91 

Q( 

UJ 

B5 

67 

67 

3.2-3 .3 

B7 

92 

97 98 

100 r02 

ro2 

91 

85 

67 

3 .4-3. s 

3 .6-3.7 

87 

B7 

B8 

B8 

95 97 

92 95 

98 100 

97 98 

100 

9B 

9I 

9T 

B5 

85 

67 

67 

3. B-3.9 

4.0-4.L 

4.2-4.3 

87 

B7 

B7 

BB 

B8 

8B 

BB 92 

BB 88 

88 BB 

9s 97 

92 95 

BB 92 

97 

95 

92 

9L 

B7 

B7 

B5 

B2 

B2 

67 

67 

67 

4.4- + 

87 

B8 

88 88 

BB BB 

BB 

B7 

B2 

67

76 

Appendix VI. Adjustment table for age to market weíght 

Body wÈ. 

(ke) 

75 

76 

77 

78 

79 

80 

B1 

B2 

B3 

B4 

B5 

86 

B7 

8B 

89 

90 

91 

92 

93 

94 

95 

96 

97 

9B 

99 

100 

101 

702 

103 

104 

105 

155 

Ls4 

153 

L52 

151 

150 

L4B 

r47 

746 

L46 

L4s 

L44 

143 

L42 

141 

140 

139 

138 

l-37 

L37 

136 

135 

134 

134 

133 

r32 

131 

131 

r30 

130 

l-29 

159 l_67 

L56 L59 

r55 L57 

L54 156 

153 155 

r52 l.54 

151 153 

150 r52 

148 151 

148 150 

147 L49 

746 748 

L45 147 

L44 L46 

L43 145 

r42 744 

L4I L43 

r40 L42 

139 r4L 

139 ]-4L 

138 140 

137 139 

136 138 

136 138 

135 L37 

134 136 

133 135 

133 135 

132 L34 

r32 133 

131 732 

163 165 

L6L 163 

160 L62 

158 161 

L57 L59 

156 rs8 

155 L57 

754 156 

153 155 

L52 L54 

r51 153 

150 752 

L49 151 

148 1s0 

L47 L49 

L46 148 

r4s L47 

L44 l-46 

L43 L45 

r43 r4s 

L42 r44 

L41 L43 

140 142 

139 L4L 

138 L40 

138 L40 

L37 139 

L37 139 

136 138 

135 r37 

L34 L36 

usted 

L67 t69 

165 l-67 

L64 ]66 

L63 165 

L62 L64 

160 163 

159 L62 

r5B 160 

\57 L59 

156 158 

155 L57 

L54 156 

153 155 

r52 r54 

151 153 

150 152 

L49 151 

148 150 

1,47 L49 

L46 I4B 

L46 r47 

r45 L46 

144 l-46 

L43 A45 

L42 744 

142 L44 

L4L 143 

140 L42 

L40 l4r 

139 ]'4]- 

138 140 

L7I L74 

L69 L77 

168 I70 

167 L69 

L66 168 

L65 L67 

L64 166 

163 l-65 

I6L L64 

160 L62 

159 r6L 

158 160 

L57 159 

156 158 

155 L57 

r54 L56 

153 1s5 

L52 L54 

151 153 

150 L52 

1"49 151 

r4B 150 

148 150 

747 L49 

146 748 

146 L4B 

r45 L47 

144 L46 

L43 L4s 

L42 L44 

L4L L43 

L76 r78 

L75 I77 

L72 L76 

L7L L73 

L70 I72 

L69 L7L 

168 L70 

L67 169 

L66 168 

165 l-67 

163 L66 

L62 L64 

161 163 

160 L62 

159 L6r 

r5B 160 

L57 159 

156 158 

155 L57 

r54 156 

153 155 

L52 754 

r52 L54 

151 r53 

r50 L52 

L49 151 

L49 1s0 

148 150 

L47 L49 

L46 148 

L4s r47 

Continued.

77 

Appendix VI. 

(Continued) 

Body wt. 

(kg) 

75 

76 

77 

78 

79 

BO 

BI 

82 

OJ 

B4 

B5 

B6 

B7 

B8 

B9 

90 

91 

92 

93 

94 

9s 

96 

97 

98 

99 

100 

101 

LO2 

103 

104 

105 

180 rB2 IB4 186 188 

t79 181 183 185 787 

I7B 1BO 182 T84 186 

L77 L79 1Bl 183 rB5 

r75 L77 779 181 183 

773 t76 r78 180 tB2 

L72 r74 L77 L79 181 

L7l- r73 L75 L78 180 

L70 L72 r74 L76 L79 

169 L7L L73 175 I77 

168 L70 772 L74 176 

166 168 I70 I72 L74 

165 T67 L69 l-7L L73 

L64 L66 168 L70 L72 

L63 165 L67 L69 L77 

162 L64 166 168 r70 

161 L63 165 l.67 ],69 

160 L62 764 L66 168 

159 161 163 L65 t67 

1s8 160 162 l.64 ]-66 

r57 159 161 163 ]'65 

156 ls8 160 L62 L64 

156 158 159 161 163 

155 L57 r59 160 L62 

r54 156 rs8 159 161 

153 155 L57 159 160 

t52 r54 156 158 160 

151 153 155 r57 159 

150 L52 154 156 158 

150 151 153 155 l-57 

749 1s1 1s2 Ls4 756 

Adjusted age in days 

190 l-92 r94 

189 191 L93 

188 190 L92 

L87 189 L9T 

185 IB7 189 

184 186 lBB 

183 185 LB7 

L82 rB4 186 

181 183 185 

r79 181 183 

L78 lBO IB2 

L76 L7B TBI 

L75 r77 T79 

T74 L76 L7B 

L73 r75 L77 

!72 1_74 176 

L7L L73 T75 

r70 r72 L74 

L69 T7L L73 

168 L70 172 

1"67 l69 L70 

166 168 L70 

165 t67 L69 

L64 166 168 

163 165 ]'67 

762 L64 L66 

L6L 163 165 

16r 162 L64 

160 161 163 

159 161 l-62 

158 160 162 

L96 198 200 

195 l'97 199 

L94 796 198 

193 195 Lg7 

LgL 193 195 

190 L92 L94 

189 191 193 

188 190 L92 

LB7 rB9 191 

185 rB7 r89 

LBî 186 188 

183 rB5 L87 

rB2 184 186 

180 I82 184 

r79 181 183 

L78 1BO LB2 

r77 L79 181 

L76 178 180 

175 L77 L79 

L74 L76 r78 

L72 L74 L76 

L7L T73 L75 

77L L72 L74 

L70 L72 173 

L69 t7L r72 

168 170 L72 

L67 L69 L7T 

166 168 L70 

16s 167 L69 

164 L66 168 

163 165 767 

ContÍnued.

7B 

Appendix VI. 

(Conrinued) 

Body wt. 

(ke) 

75 

76 

77 

78 

79 

BO 

81 

B2 

83 

' .84 

85 

86 

B7 

B8 

B9 

90 

91 

92 

93 

94 

9s 

96 

97 

9B 

99 

r00 

101 

L02 

103 

104 

105 

202 204 

20L 203 

200 202 

L99 207 

L97 199 

L96 198 

195 L97 

L94 L96 

193 195 

191 193 

190 L92 

189 191 

1BB 190 

186 188 

185 r87 

L84 186 

183 185 

782 184 

181 183 

180 t_Bz 

I78 180 

777 L79 

176 r7B 

L75 l-77 

I74 l-76 

t73 r75 

L73 L74 

L72 L74 

L7T L73 

L70 L72 

t69 L7L 

206 

205 

204 

203 

207 

200 

l99 

19B 

L97 

195 

L94 

193 

L92 

190 

189 

lBB 

l-87 

186 

184 

184 

182 

181 

180 

l-79 

178 

t77 

L76 

L75 

175 

l-74 

l-73 

Adiusted a 

208 2lL0 

207 209 

206 208 

205 207 

203 205 

202 204 

20L 203 

20a 202 

r99 20L 

L97 A99 

796 198 

195 r97 

794 L96 

L92 L94 

191 193 

190 792 

189 191 

1BB 190 

186 1BB 

185 787 

184 186 

183 185 

182 rB4 

181 rB3 

180 l-82 

L79 181 

L78 180 

177 L79 

L76 L7B 

776 177 

L75 L76 

272 

277 

2LO 

209 

207 

206 

205 

204 

203 

20L 

200 

L99 

198 

L96 

195 

L94 

193 

L92 

190 

189 

1BB 

L8l 

IB6 

185 

184 

183 

r82 

1BI 

tB0 

1,79 

t77 

in da 

2L4 

21"3 

272 

2LL 

209 

208 

207 

206 

205 

203 

202 

20l- 

200 

198 

L97 

L96 

r95 

L94 

192 

191 

190 

189 

LB7 

L87 

186 

185 

184 

183 

I82 

lBl 

l-79 

2L6 2IB 

2L5 2L7 

2L4 2L6 

2L3 215 

zLL 2L3 

2L0 272 

209 2rr 

208 270 

207 209 

205 207 

204 206 

203 205 

202 204 

200 202 

L99 20I 

r98 200 

L97 L99 

L96 198 

L94 L96 

193 195 

L92 r94 

191 193 

189 191 

188 190 

1BB 189 

L87 189 

186 TBB 

185 rB7 

184 186 

183 185 

181 183 

220 222 

2L9 22L 

2r8 220 

2L7 2L9 

2L5 277 

2t4 216 

2L3 2L5 

2r2 2L4 

zLT 2L3 

209 21L 

208 2L0 

207 209 

206 208 

204 206 

203 205 

202 204 

20L 203 

200 202 

198 200 

r97 L99 

L96 198 

195 L97 

193 195 

L92 r94 

191 193 

190 L92 

189 LgL 

189 190 

1BB 190 

LB7 189 

r85 l-87 

Continued.

79 

Appendix 

VI. 

(Continued) 

Body wt. 

(ke) 

75 

76 

77 

7B 

79 

BO 

B1 

B2 

OJ 

B4 

B5 

B6 

B7 

BB 

B9 

90 

9L 

92 

93 

94 

95 

96 

97 

9B 

99 

100 

101 

L02 

103 

104 

105 

Adjusted age in days 

224 226 228 230 232 234 236 238 

223 225 227 229 23r 233 235 237 

222 224 226 228 230 232 234 236 

22I 223 225 227 229 237 233 235 

2L9 22L 223 225 227 229 23I 233 

2LB 220 222 224 226 228 230 .232 

277 2Ig 22L 223 225 227 22g 23L 

2L6 zLB 220 222 224 226 228 230 

2L5 2L7 279 22L 223 225 227 229 

2l-3 2L5 2L7 2L9 22L 223 225 227 

2L2 2I4 2L6 2IB 220 222 224 226 

27L 2L3 2L5 2L7 2L9 22L 223 225 

2L0 2L2 274 2L6 zLB 220 222 224 

208 zLO 2L2 2L4 2L6 zLB 220 222 

207 209 zIL 2L3 2L5 2L7 2L9 22I 

206 208 2I0 2L2 214 2l:6 2LB 220 

205 207 209 2LI 2L3 2l-5 2L7 2Lg 

204 206 208 2]I0 2L2 2L4 2L6 zLB 

202 204 206 208 2IO 2L2 2L4 216 

20L 203 205 207 209 zLL 2L3 2L5 

200 202 204 206 208 2I0 2L2 2I4 

L99 20I 203 205 207 209 2LL 2L3 

I97 L99 20L 203 205 207 209 2LL 

196 r9B 200 202 204 206 208 2LO 

195 197 199 20\ 203 205 207 2og 

L94 L96 198 200 202 204 206 208 

193 195 r97 r99 20L 203 205 207 

191 193 195 r97 L99 zOL 203 205 

191 L92 L94 L96 198 2OO 202 204 

191 191 193 195 r97 r99 20:- 203 

rB9 191 L92 r94 L96 r9B 200 202

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