Great Lakes Dairy Sheep Symposium - the Department of Animal ...

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In dairy cows high concentrations of MU and BU have been associated with reductions in reproductive efficiency (Ferguson and Chalupa, 1989). Similar findings have been reported in ewes by Bishonga et al. (1994), who found markedly negative effects on sheep embryos cultivated in vitro when MU was equal to or higher than 43 mg/dl of urea, and by Molle et al. (2001), who reported decreased fertility when BU was above 45 mg/dl. High concentrations of MU have been also associated with increased incidence of other disturbances (Table 11). Milk sampling to measure milk urea Since MU concentration shows a considerable variability among animals fed the same diet, it should always be measured in pooled samples of milk taken from at least 8 to 10 sheep in the same stage of lactation. First lactation ewes, due to their higher protein turnover and higher consumption of amino acids as energetic fuels to sustain growth, have 5-10 mg/dl higher MU concentration compared to mature ewes (Cannas, 2004). The differences in MU concentrations obtained at different moments of milking are small and non-significant in practical terms. Thus, if individual milk samples need to be collected for MU analyses, the first milk produced by the ewes can be used. Milk urea can be measured in the laboratory by various very accurate analytical methods. It is important to pay attention to the units of measurements used. In some countries milk urea is expressed as "milk urea nitrogen". Since nitrogen makes up 46.65% of the urea molecule, when the analyses are reported as "milk urea nitrogen" the values are about one half than when they are expressed as "milk urea", as it is done in this publication. Milk urea can be accurately measured on farm using accurate portable analyzers available in the market. Tests based on strips for cow milk may bring to very erroneous estimates when applied to sheep milk (Cannas, 2004). Reference values of milk urea in sheep Based on the previous discussion on milk urea and optimal dietary protein concentration, it is likely that MU higher than 40-50 mg/dl is associated with excess dietary protein and lower reproductive efficiency, while values lower than 25 mg/dl are associated with insufficient dietary protein and low milk production. These values are higher than those suggested for dairy cattle. Indeed, when the CP concentration of the diet was the same, MU concentrations were 5-15 mg/dl higher for dairy ewes than for dairy cows, probably because the level of intake in sheep is generally higher than in cattle (Cannas, 2004). At the same time, based on reproductive studies mentioned above, dairy sheep seem to be more resistant to negative effects of N excesses than dairy cattle. When the sward is young and its CP concentrations are high, MU concentrations higher than 60 mg/dl are often found in sheep. These levels are certainly associated with a large excess of protein intake, poor health status and reproductive efficiency, and increases in energy 106
equirements. The relationship found between MU and dietary CP concentration (Equation [8]) may be used to estimate the protein concentration in the diet by measuring milk urea (Table 10). This could be particularly useful for grazing animals, for which some knowledge on dietary CP concentration would greatly help the choice of type and amount of feed supplements required to complete and balance the diets. Table 10 - Relationship between MU or BU and dietary CP concentrations in sheep (based on equation [8]. When dietary CP concentration is unknown, MU or BU may be used for its estimation. The numbers in italics represent the range for lactating ewes fed well-balanced diets. CP (% DM) 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 16.0 Milk or blood urea (mg/dl) 15.4 17.6 19.8 22.0 24.2 26.4 28.6 30.8 33.0 CP (% DM) 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 Milk or blood urea (mg/dl) 35.2 37.4 39.6 41.8 44.0 46.2 48.4 50.6 52.8 Usage of MU for dietary formulation MU can be used to help diet (pasture + concentrates + hay + silages) balancing in many ways: a) to predict average diet CP concentration when pasture intake and quality is unknown (Table 10); b) to define the type of supplements or feeding strategies best suited to reduce MU when it is in excess, or to increase MU when it is too low (Table 11); and c) to indirectly monitor animal’s energy balance or health status. For instance, if the diet has a moderate protein concentration and MU is high, it is likely that some stress or excessive energy deficit is inducing a high use of amino acids as gluconeogenic precursors and thus high MU concentration. Table 11 – Classification of milk urea thresholds, causes and effects in lactating ewes. Milk urea concentration Causes Effects >45-50 mg/dl < 20-25 mg/dl • Too high dietary CP concentration • Correct dietary CP concentration but too much degradable CP • Shortage of rumen fermented carbohydrates • Too low CP dietary concentration • Too low CP degradability with correct dietary CP concentration 107 • Waste of CP • Waste of energy for urea production • Reduced fertility • Diarrhoea, mastitis, mammary oedemas • Low rumen bacteria number and activity • Low digestibility and rumen vitamin production • Low intake and milk yield • Low fertility • Oedema (intermandibular space) • Poor quality of the fleece; low fleece production
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Proceedings of the 11 th Annual GRE
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Table of Contents Program of Events
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Program of Events Thursday, Novembe
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Speakers at the symposium site in B
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Gold: Sponsors Babcock Institute fo
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“YOU WANT TO MILK WHAT?” IMPORT
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already have their milking faciliti
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efficient or just selling milk (or
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production doubles. However, there
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Total production (pounds) Percentag
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Milk production (pounds) Average mi
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Percentage of ewes in each system 1
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5. Ice Cream and Butter: • raw mi
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3. Fresh Cheeses made from pasteuri
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The Vermont Cheese Council (www.vtc
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1 x Brine Tank (10’ long x 3 ft.
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LAMB REARING STRATEGIES: FARMER PAN
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BONNIEVIEW FARM’S LAMB REARING ST
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REARING LAMBS AT 3-CORNER FIELD FAR
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PROFITABILITY OF SMALL RUMINANT FAR
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Table I. General Farm Description L
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Table 4. Business Balance Sheet Ass
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Table 5. Income Statement Income Av
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Lifestyle is a definite reason for
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Grossman et al., 1999). Animals wit
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Physiological Factors Affecting Lac
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Recently, it has been hypothesized
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(co)variate in the genetic model us
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show that milk production increases
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Figure 6 - Lactation curves of ewes
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milk yield (g/d) 3000 2500 2000 150
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a genetic potential to produce more
Page 65 and 66: when compared with the control grou
Page 67 and 68: probability (%) 70 60 50 40 30 20 1
Page 69 and 70: considered “healthy” if every S
Page 71 and 72: Finally, udder health has to be con
Page 73 and 74: De Maria Ghionna C., Dell’Aquila.
Page 75 and 76: Manalu, W., Sumaryadi, M.Y., Sudjat
Page 77 and 78: Rupp R., Boichard D., Barbat A., As
Page 79 and 80: Introduction MILK FAT SYNTHESIS AND
Page 81 and 82: The variety of fatty acids allows t
Page 83 and 84: Germany); we have shown previously
Page 85 and 86: Manipulating Milk Fatty Acid Compos
Page 87 and 88: increase in rumen output of vacceni
Page 89 and 90: Luna et al., 2005; Nudda et al., 20
Page 91 and 92: Cabiddu, A., M. Decandia, M. Addis,
Page 93 and 94: MANAGING YOUR OWN RETAIL SHOP: MARK
Page 95 and 96: The Reality our feta demonstrates t
Page 97 and 98: Meat and meat dishes: 1. Legs: whol
Page 99 and 100: 5. We have daily visits from chefs
Page 101 and 102: HOW TO GRAZE DAIRY SHEEP AND SUPPLE
Page 103 and 104: significantly increase milk product
Page 105 and 106: All parameters are significantly di
Page 107 and 108: Table 6 - Dry matter intake and mil
Page 109 and 110: animals can reduce intake, as they
Page 111 and 112: Milk fat and protein concentrations
Page 113 and 114: fat concentration can be used as a
Page 115: (1998), working with adult Sarda ew
Page 119 and 120: that there have not been enough stu
Page 121 and 122: Grazing methods Grazing methods are
Page 123 and 124: How should the number of paddocks b
Page 125 and 126: Table 16 - Description of four past
Page 127 and 128: a) concentrates supplied during mil
Page 129 and 130: References Arnold G.W., and Dudzins
Page 131 and 132: supplemented with corn grain. Optio
Page 133 and 134: succeeding add on pastures smaller
Page 135 and 136: diverse forage have much to do with
Page 137 and 138: dairy farming. In fact, Vermont agr
Page 139 and 140: thermized (holding at a temperature
Page 141 and 142: speaking, the risks associated with
Page 143 and 144: FARMER PANEL ON LABOR HOW TO ATTRAC
Page 145 and 146: • Animal Health Products • Spec
Page 147 and 148: Cultivating Healthy Communities UVM
Page 149 and 150: 139
Page 151 and 152: Hudson Valley Camemberts Pure Sheep
Page 153 and 154: Premier Dairy Service, LLC Argyle,
Page 155 and 156: www.vermontagriculture.com 145
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