University of Saskatchewan, Saskatoon, SK, Canada.
Theriogenology. 2009 Dec;72(9):1237-50. doi: 10.1016/j.theriogenology.2009.07.019. Epub 2009 Sep 24.
The objective of this study was to determine the effects of low versus physiologic plasma progesterone concentrations during the ovulatory wave on fertility in cattle. Suckled beef cows (Bos taurus; n=129) and pubertal heifers (Bos taurus; n=150) at random stages of the estrous cycle were given a luteolytic dose of prostaglandin F(2 alpha) (500 microg cloprostenol; PGF) twice, 11 d apart. Ten days after the second PGF treatment, cattle were given estradiol benzoate im (1.5 and 1.0mg for cows and heifers, respectively) and a progesterone-releasing intravaginal device (Cue-Mate) with a single pod containing 0.78 g progesterone (Day 0). Cattle in the low-progesterone group (n = 148) received a luteolytic dose of PGF on Day 0, whereas those in the high-progesterone (i.e., physiologic plasma concentrations) group (n=131) were allowed to retain their corpora lutea. On Day 8, the Cue-Mate was removed, and PGF was given to both groups. Fifty-four hours to 56 h later, cattle received 12.5mg of porcine LH (pLH) im and were concurrently artificially inseminated. The dominant follicle in the low-progesterone group was larger (P<0.001) than that in the high-progesterone group on the day of insemination (14.9+/-0.3mm vs. 12.7+/-0.3mm, mean+/-SEM). At 7 d after ovulation, the low-progesterone group had a larger corpus luteum (24.5+/-0.54 mm vs. 21.9+/-0.64 mm, P<0.01) and higher plasma progesterone concentration (4.0+/-0.3 vs. 3.1+/-0.2, P<0.01) than that of the high-progesterone group. However, pregnancy rates did not differ (79 of 148, 53.4%, and 70 of 131, 53.4%) for low- and high-progesterone groups, respectively). In summary, low circulating progesterone concentrations during the growing phase of the ovulatory follicle resulted in a larger dominant follicle and a larger CL that produced more progesterone, with no significant effect on pregnancy rate.
本研究旨在确定排卵波中低与生理血浆孕酮浓度对牛生育力的影响。随机处于发情周期不同阶段的哺乳期肉牛（Bos taurus；n=129）和青春期小母牛（Bos taurus；n=150）接受了两次前列腺素 F（2α）（500μg氯前列醇；PGF）的溶黄体剂量，间隔 11d。第二次 PGF 处理后 10d，牛肌肉内注射苯甲酸雌二醇（牛用 1.5mg，小母牛用 1.0mg），并植入含有 0.78g 孕酮的单个药栓的阴道孕酮释放装置（Cue-Mate）（第 0 天）。低孕酮组（n=148）在第 0 天接受了溶黄体剂量的 PGF，而高孕酮组（即生理血浆浓度）（n=131）保留了黄体。第 8 天，取出 Cue-Mate，两组均给予 PGF。54 至 56h 后，牛肌肉内注射 12.5mg 猪 LH（pLH）并同时进行人工授精。低孕酮组的主导卵泡在授精日比高孕酮组更大（P<0.001）（14.9+/-0.3mm 对 12.7+/-0.3mm，平均值+/-SEM）。排卵后 7d，低孕酮组黄体（24.5+/-0.54mm 对 21.9+/-0.64mm，P<0.01）和血浆孕酮浓度（4.0+/-0.3 对 3.1+/-0.2，P<0.01）均大于高孕酮组。然而，两组的妊娠率无差异（低孕酮组 148 头中有 79 头，即 53.4%，高孕酮组 131 头中有 70 头，即 53.4%）。总之，排卵卵泡生长阶段低循环孕酮浓度导致主导卵泡更大，黄体更大，产生更多孕酮，但对妊娠率无显著影响。
