Kummerfeld H L, Oltenacu E A, Foote R H
J Dairy Sci. 1978 Dec;61(12):1773-7. doi: 10.3168/jds.S0022-0302(78)83801-6.
Cyclic patterns of progesterone in milk were studied in 262 Holstein cows. Milk progesterone data were obtained from 153 cows for at least 75 days after conception as indicated by continuous high progesterone concentrations in milk for 28 days or more following artificial insemination. Cycling was reinitiated in 11 of these cows between 28 and 75 days after breeding, for an estimated 7.2% rate of embryo-fetal mortality. This was considerably less than a corresponding rate of 22.7% estimated for this herd by the delayed returns to estrus (28 to 75 days). In 350,180 cows inseminated with semen from Holstein bulls the estimated embryo-fetal mortality by the same delayed return to service method was 12.5%. Biases in this latter method of estimation are discussed.
对262头荷斯坦奶牛的乳中孕酮的周期性模式进行了研究。如人工授精后乳中孕酮持续高浓度达28天或更长时间所示，从153头奶牛获得了受孕后至少75天的乳孕酮数据。这些奶牛中有11头在配种后28至75天之间重新开始循环，估计胚胎-胎儿死亡率为7.2%。这大大低于通过发情延迟回归（28至75天）估计的该牛群22.7%的相应比率。在350180头用荷斯坦公牛精液授精的奶牛中，通过相同的延迟配种方法估计的胚胎-胎儿死亡率为12.5%。讨论了后一种估计方法中的偏差。
