Detilleux J C, Freeman A E, Miller L D
Department of Animal Science, Iowa State University, School of Veterinary Medicine, Ames 50011.
Am J Vet Res. 1991 Sep;52(9):1551-5.
One hundred and fifty lactating Holstein cows from 2 genetic lines selected for high and average milk production were used in the study. Sera from 6 annual herd tests were analyzed by agar-gel immunodiffusion test for antibodies to bovine leukemia virus. Odds of being seropositive were analyzed by use of stepwise and backward logistic regression procedures. Analysis within birth year revealed that estimated in odds increased by 0.19/year of age among cows of the high genetic line and by 0.43 among cows of the average genetic line. This was accompanied by a more important cohort effect among high producers than among average producers.
本研究使用了150头来自两个因高产奶量和平均产奶量而选择的遗传品系的泌乳荷斯坦奶牛。通过琼脂凝胶免疫扩散试验分析了6次年度牛群检测的血清中牛白血病病毒抗体。使用逐步和向后逻辑回归程序分析血清阳性的几率。按出生年份进行的分析显示，高遗传品系奶牛的估计几率每年增加0.19，平均遗传品系奶牛的估计几率每年增加0.43。与平均生产者相比，高产者中存在更重要的队列效应。
