Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
J Dairy Sci. 2011 Nov;94(11):5487-93. doi: 10.3168/jds.2011-4395.
The effect of lameness on the fertility of dairy cattle is well recognized. But, the effect of lameness on the fertility of seasonally breeding cattle in pasture-based systems is less well characterized. This prospective cohort study of 463 cows on 1 farm in the lower North Island of New Zealand was designed to assess the effect of clinical lameness, as identified by farm staff, on the hazard of conception after the planned start-of-mating date. A Cox proportional hazards model with time-varying covariates was used. After controlling for the effect of parity, breed, body weight at calving, and calving-to-planned start of mating interval, the daily hazard of conception for cows identified as lame was 0.78 (95% confidence interval: 0.68-0.86) compared with non-lame cows. Lame cows took 12 d longer to get pregnant compared with their non-lame counterparts.
跛行对奶牛繁殖力的影响已得到充分认识。但是，在基于牧场的系统中，季节性繁殖牛的跛行对繁殖力的影响还不太明确。这项前瞻性队列研究共纳入了新西兰北岛下部一个农场的 463 头奶牛，旨在评估由农场工作人员确定的临床跛行对计划配种日期后受孕的风险的影响。使用了具有时变协变量的 Cox 比例风险模型。在控制了胎次、品种、产犊时体重和产犊至计划配种间隔后，与非跛行牛相比，跛行牛的受孕日风险每天降低 0.78（95%置信区间：0.68-0.86）。与非跛行牛相比，跛行牛怀孕所需的时间长了 12 天。
