Pollari F L, DiGiacomo R F, Evermann J F
Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle 98195.
Am J Vet Res. 1993 Sep;54(9):1400-3.
Bovine leukemia virus (BLV) infection and culling of cows in a commercial dairy herd were evaluated to determine whether a relation existed between the 2 factors. Cattle from the study population, a Holstein dairy herd consisting of approximately 400 milking cows, were tested for antibodies to BLV, using the agar gel immunodiffusion test, semiannually for 2 years, annually for 2 years, and when cattle were culled. Complete records of BLV test results were available for 849 (79%) of the 1,078 cattle that had at least 1 test during the study period. Using the Cox hazard model, the cull hazard rates (culls/cow-months) were greater for BLV seropositive cows than for seronegative cows > 36 months old. Hence, among older dairy cows, BLV-infected cows were culled prematurely, compared with uninfected cows.
对商业奶牛群中牛白血病病毒（BLV）感染情况及奶牛淘汰情况进行了评估，以确定这两个因素之间是否存在关联。研究群体为一个约有400头泌乳奶牛的荷斯坦奶牛群，使用琼脂凝胶免疫扩散试验，每半年检测一次牛群中牛白血病病毒抗体，持续2年，之后每年检测一次，持续2年，且在奶牛被淘汰时也进行检测。在研究期间至少接受过一次检测的1078头牛中，849头（79%）有完整的牛白血病病毒检测结果记录。使用Cox风险模型，36个月以上的BLV血清阳性奶牛的淘汰风险率（淘汰数/牛月数）高于血清阴性奶牛。因此，在年龄较大的奶牛中，与未感染的奶牛相比，感染BLV的奶牛被过早淘汰。
