Norby B, Bartlett P C, Byrem T M, Erskine R J
Department of Large Animal Clinical Sciences, Michigan State University, East Lansing 48824.
Department of Large Animal Clinical Sciences, Michigan State University, East Lansing 48824.
J Dairy Sci. 2016 Mar;99(3):2043-2052. doi: 10.3168/jds.2015-10089. Epub 2015 Dec 24.
The objective of this study was to determine the association between individual cow-level milk production and bovine leukemia virus (BLV) infection as measured by milk BLV-ELISA. Dairy Herd Improvement technicians collected milk samples from 10 cows from each of first, second, third, and 4+ parity cows in 105 Holstein herds with ≥ 120 milking cows. Milk samples were tested for the presence of anti-BLV antibodies by ELISA. Additional data regarding the cows and the herds were collected by farm survey and Dairy Herd Improvement records. A set of mixed-effect models using all cows and only 2+ parity cows were used to investigate the association between BLV ELISA-corrected optical density and 305-d mature equivalents of individual cows. The BLV milk positivity was associated with decreased 305-d mature-equivalent yields, especially among the older cows. Additionally, increasing milk ELISA-corrected optical density was associated with increasing loss of milk production at the cow level. In summary, our results provide evidence that BLV infection is associated with decreased milk production in Michigan dairy cows.
本研究的目的是确定个体奶牛水平的产奶量与通过牛奶BLV-ELISA检测的牛白血病病毒（BLV）感染之间的关联。奶牛群改良技术员从105个拥有≥120头泌乳奶牛的荷斯坦奶牛群中，分别采集了头胎、二胎、三胎和4胎以上奶牛各10头的牛奶样本。通过ELISA检测牛奶样本中抗BLV抗体的存在情况。通过农场调查和奶牛群改良记录收集了有关奶牛和牛群的其他数据。使用所有奶牛以及仅使用2胎以上奶牛的一组混合效应模型，来研究BLV ELISA校正光密度与个体奶牛305天成熟当量之间的关联。BLV牛奶阳性与305天成熟当量产量降低有关，尤其是在年龄较大的奶牛中。此外，牛奶ELISA校正光密度增加与奶牛个体产奶量损失增加有关。总之，我们的结果提供了证据，表明BLV感染与密歇根州奶牛的产奶量下降有关。
