Banos G, Coffey M P, Wall E, Brotherstone S
Department of Animal Production, School of Veterinary Medicine, Box 393, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.
J Dairy Sci. 2006 Jun;89(6):2222-32. doi: 10.3168/jds.S0022-0302(06)72293-7.
Weekly body condition score (BCS) and live weight records were used to calculate energy content (EC) and cumulative effective energy balance (CEEB) for 508 Holstein-Friesian cows in their first lactation. Cows were raised on an experimental farm and had calved between 1991 and 2000. Energy content was an estimate of the actual energy level of a cow at any given stage of lactation, whereas CEEB was associated with the total body energy content as defined by accumulated weekly energy balance changes since the onset of lactation. Genetic evaluations were computed for the 3 body energy traits (BCS, EC, and CEEB) for each week of first lactation. Random regression models were used to assess the association between first-lactation weekly genetic evaluations for body energy and monthly test-day log-transformed SCC, clinical mastitis, and other udder problems in the first 3 lactations. There was a significant effect of at least one body energy trait at any stage of first lactation past wk 3 on SCC in the first 3 lactations. Maximum genetic correlation estimates were -0.18 (+/-0.04) between wk-16 BCS and SCC in the first 2 lactations, -0.18 (+/-0.04) between wk-11 EC and SCC in the first 2 lactations, and -0.17 (+/-0.07) between wk-6 CEEB and SCC in the first 2 lactations. The effect of body energy traits on clinical mastitis was, in general, nonsignificant; nevertheless, moderate genetic correlations were estimated, ranging from -0.05 (+/-0.07) to -0.25 (+/-0.15). The effect of body energy traits on udder problems other than mastitis was negligible in all cases. Results suggest that, amongst the traits studied here, BCS, EC, and CEEB in the first 3 to 4 mo of lactation 1 had the greatest genetic association with SCC and mastitis in first, second, and, to a lesser extent, third lactations.
利用每周的体况评分（BCS）和活重记录，计算了508头处于第一个泌乳期的荷斯坦 - 弗里生奶牛的能量含量（EC）和累积有效能量平衡（CEEB）。这些奶牛饲养在一个实验农场，于1991年至2000年间产犊。能量含量是对奶牛在泌乳任何给定阶段实际能量水平的估计，而CEEB与自泌乳开始以来每周累积能量平衡变化所定义的总体能量含量相关。计算了第一个泌乳期每周的3个体能量性状（BCS、EC和CEEB）的遗传评估值。使用随机回归模型评估第一个泌乳期每周体能量的遗传评估值与前3个泌乳期每月测定日对数转换后的体细胞计数（SCC）、临床乳腺炎及其他乳房问题之间的关联。在泌乳第3周后的第一个泌乳期的任何阶段，至少有一个体能量性状对前3个泌乳期的SCC有显著影响。在头两个泌乳期，第16周的BCS与SCC之间的最大遗传相关估计值为 -0.18（±0.04），第11周的EC与SCC之间为 -0.18（±0.04），第6周的CEEB与SCC之间为 -0.17（±0.07）。一般来说，体能量性状对临床乳腺炎的影响不显著；然而，估计的中等遗传相关范围为 -0.05（±0.07）至 -0.25（±0.15）。在所有情况下，体能量性状对除乳腺炎外的乳房问题的影响可忽略不计。结果表明，在此处研究的性状中，泌乳第1期前3至4个月的BCS、EC和CEEB与第一、第二泌乳期以及在较小程度上与第三泌乳期的SCC和乳腺炎具有最大的遗传关联。
