Britt J H, Hafs H D, Stevenson J S
J Dairy Sci. 1978 Apr;61(4):513-5. doi: 10.3168/jds.S0022-0302(78)83628-5.
Holstein heifers (95) were given two injections of prostaglandin F2alpha, the first on day 0 and the second either at 0600 h or 1800 h on day 12. Interval from the second treatment to first observation of estrus did not differ between heifers treated during the morning (69.8 +/- 4.4 h) or evening (72.7 +/- 5.2 h). However, estrus was detected sooner after treatment of heifers during July 1975 (49 +/- 2 h) than after treatment during June 1976 (85 +/- 8 h). Estrus began at 64 +/- 5, 73 +/- 7, and 76 +/- 7 after the second injection during August 1975, October 1976, and December 1975. Heifers treated during the morning in October were detected in estrus sooner (57 +/- 3 versus 95 +/- 13 h) than those treated during the evening. An interaction of season by time may affect interval from prostaglandin F2alpha treatment to onset of estrus.
95头荷斯坦小母牛接受了两次前列腺素F2α注射，第一次在第0天，第二次在第12天的06:00或18:00。上午（69.8±4.4小时）或晚上（72.7±5.2小时）接受治疗的小母牛，从第二次治疗到首次观察到发情的间隔没有差异。然而，1975年7月治疗的小母牛（49±2小时）比1976年6月治疗的小母牛（85±8小时）在治疗后更早检测到发情。1975年8月、1976年10月和1975年12月，第二次注射后发情分别在64±5、73±7和76±7小时开始。10月上午接受治疗的小母牛比晚上接受治疗的小母牛更早检测到发情（57±3小时对95±13小时）。季节与时间的交互作用可能会影响从前列腺素F2α治疗到发情开始的间隔。
