Stewart R J, Campbell J R, Janzen E D, McKinnon J
Department of Herd Medicine and Theriogenology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon.
Can Vet J. 1998 Oct;39(10):638-41.
A prospective observational study of a breeding season in a Saskatchewan community pasture was carried out to determine the cause or causes of a chronic infertility problem. There were 774 cows, from 27 herds, divided into 4 breeding groups (A,B,C,D) on the pasture. Cows entering the pasture in May were weighed, had their body condition scored and height measured. All bulls received breeding soundness examinations and a preputial wash, which was cultured for Tritrichomonas foetus and Campylobacter foetus subsp. venerealis. In July, cows were also weighed and had their body condition scored and again when they left the pasture. In addition, cows were pregnancy checked when they left the pasture. Bulls were tested again for Tritrichomonas foetus at the end of the grazing season. Two breeding groups had T. foetus-positive bulls and an average pregnancy of 84%, which was significantly lower than that of the two T. foetus negative groups (93.5%) (P = 0.0001). A cow was 2.97 times less likely to be pregnant if she had been exposed to T. foetus-positive bulls. Cows with average daily gains above the mean for the pasture were 2.12 times more likely to be pregnant. Body condition score upon entering and leaving the pasture, height, age, and breeding group were significant predictors of average daily gain.
在萨斯喀彻温省一个社区牧场进行了一项关于繁殖季节的前瞻性观察研究，以确定慢性不育问题的一个或多个原因。共有来自27个牛群的774头母牛，在牧场上被分为4个繁殖组（A、B、C、D）。5月份进入牧场的母牛进行了称重、体况评分和身高测量。所有公牛都接受了繁殖健康检查和包皮清洗，并对清洗液进行培养以检测胎儿三毛滴虫和胎儿弯曲杆菌性病亚种。7月份，母牛再次进行称重和体况评分，离开牧场时也进行了同样的操作。此外，母牛离开牧场时进行了妊娠检查。在放牧季节结束时，公牛再次检测胎儿三毛滴虫。两个繁殖组有胎儿三毛滴虫阳性的公牛，平均妊娠率为84%，显著低于两个胎儿三毛滴虫阴性组（93.5%）（P = 0.0001）。如果母牛接触过胎儿三毛滴虫阳性的公牛，其怀孕的可能性要低2.97倍。日增重高于牧场平均水平的母牛怀孕的可能性要高2.12倍。进入和离开牧场时的体况评分、身高、年龄和繁殖组是日增重的显著预测因素。
