Reimers T J, Smith R D, Newman S K
J Dairy Sci. 1985 Apr;68(4):963-72. doi: 10.3168/jds.S0022-0302(85)80916-4.
Dairy herds (476) in seven states in the northeastern United States were surveyed to determine effects of various management factors on reproductive performance. Error of estrus detection (greater than 1 ng/ml of milk progesterone) on the day of service was 5.1% for 4558 cows but was as high as 60% in some herds. Error was not affected by herd size but was greater in freestall (6.8%) than in conventional (5.2%) housing. "Standing" and "riding other cows" were the most accurate signs of estrus. Of cows in or near estrus when serviced, 28.1% were open 3 wk later, 12.9% were probably open, and 59% were probably pregnant based on analysis of milk progesterone. Conception rate, not affected by herd size or housing type, was greater for cows in estrus during the morning and serviced the same afternoon (52.2%) than for cows observed in the afternoon and serviced the next morning (47.1%). Fifty-five percent of cows open to first service were serviced again within 3 days of expected return to estrus. Days to first service and conception rates were correlated positively. Milk progesterone concentration 21 to 24 days after service predicted a cow will calve with 88.6% accuracy and that she will not with 93.9% accuracy. Veterinarians predicted a calf with 92.5% accuracy by rectal palpation.
对美国东北部七个州的476个奶牛群进行了调查，以确定各种管理因素对繁殖性能的影响。4558头奶牛在输精当天的发情检测误差（牛奶孕酮浓度大于1 ng/ml）为5.1%，但在一些牛群中高达60%。误差不受牛群规模的影响，但在散栏式牛舍（6.8%）中比传统牛舍（5.2%）中更高。“站立”和“骑跨其他奶牛”是最准确的发情迹象。根据牛奶孕酮分析，输精时处于发情期或接近发情期的奶牛中，28.1%在3周后未受孕，12.9%可能未受孕，59%可能已怀孕。受孕率不受牛群规模或牛舍类型的影响，上午处于发情期且在当天下午输精的奶牛（52.2%）比下午观察到且在第二天上午输精的奶牛（47.1%）受孕率更高。首次输精未受孕的奶牛中，55%在预期发情回归的3天内再次输精。首次输精天数与受孕率呈正相关。输精后21至24天的牛奶孕酮浓度预测奶牛产犊的准确率为88.6%，预测未产犊的准确率为93.9%。兽医通过直肠触诊预测产犊的准确率为92.5%。
