Rivera G M, Goñi C G, Chaves M A, Ferrero S B, Bo G A
Departamento de Reproducción Animal, Facultad de Agronomía y Veterinaria, Universidad Nacional de Río Cuarto, Argentina.
Theriogenology. 1998 May;49(7):1365-75. doi: 10.1016/S0093-691X(98)00083-1.
An experiment was designed to evaluate a) the effect of a progesterone-estradiol combined treatment on ovarian follicular dynamics in postpartum beef cows, and b) ovulation and the subsequent luteal activity after short-term calf removal and GnRH agonist treatment. Multiparous Angus cows (25 to 40 d after calving) were assigned to the following treatments: untreated (Control, n = 9); short term calf removal (CR, n = 8); progesterone (CIDR, n = 9) and progesterone plus estradiol-17 beta (CIDR + E-17 beta, n = 9). Progesterone treatment (CIDR) lasted 8 d and the day of device insertion was considered as Day 0. Cows in the CIDR + E-17 beta group also received an i.m. injection of 5 mg of E-17 beta on Day 1. On Day 8, calves were removed for 48 h (CR, CIDR and CIDR + E-17 beta groups) and 6 h before the end of calf removal these cows also received an i.m. injection of 8 micrograms of Busereline (GnRH). Anestrus was confirmed in all cows by the absence of luteal tissue and progesterone concentrations below 1 ng ml-1 at the beginning of the experiment. Although mean (+/- SEM) interval from the beginning of the experiment (Day 0) to wave emergence did not differ (P > 0.05) among treatment groups (Control, 1.9 +/- 1.0, range -2 to 7 d; CR, 3.9 +/- 0.7, range 0 to 6 d; CIDR, 2.8 +/- 0.5, range 0 to 4 d and CIDR + E-17 beta, 4.1 +/- 0.2, range 3 to 5), the variability was less (P < 0.05) in the CIDR + E-17 beta group. The proportion of cows ovulating 24 to 48 h after GnRH administration tended (P = 0.08) to be higher in cows from CIDR + E-17 beta group (8/9) than in those of CR (5/8) or CIDR (6/9) groups, respectively and was associated with a higher proportion (P < 0.05) of CIDR + E-17 beta treated cows (9/9) that had a dominant follicle in the growing/early static phase at the time of GnRH treatment compared to the other GnRH treated groups (5/8, and 4/9 for CR and CIDR groups, respectively). Two CR cows ovulated 0-24 h after GnRH and only one Control cow ovulated the day before the time of GnRH administration. Cows pretreated with progesterone had longer (P < 0.05) luteal lifespan (CIDR, 14.5 +/- 0.7, CIDR + E-17 beta, 13.9 +/- 0.6 d) than those not treated with CIDR (Control, 5, CR, 4.0 +/- 0.4). We conclude that progesterone plus estradiol treatment results in tightly synchronized wave emergence and high GnRH-induced ovulation rate with normal luteal activity in postpartum beef cattle.
a）孕酮 - 雌二醇联合处理对产后肉牛卵巢卵泡动态的影响；b）短期犊牛移除和促性腺激素释放激素（GnRH）激动剂处理后的排卵及随后的黄体活动。经产安格斯母牛（产犊后25至40天）被分配到以下处理组：未处理（对照组，n = 9）；短期犊牛移除（CR组，n = 8）；孕酮（阴道孕酮释放装置，CIDR，n = 9）以及孕酮加17β - 雌二醇（CIDR + E - 17β组，n = 9）。孕酮处理（CIDR）持续8天，装置插入日被视为第0天。CIDR + E - 17β组的母牛在第1天还接受了5毫克17β - 雌二醇的肌肉注射。在第8天，犊牛被移除48小时（CR组、CIDR组和CIDR + E - 17β组），并且在犊牛移除结束前6小时，这些母牛还接受了8微克布舍瑞林（GnRH）的肌肉注射。在实验开始时，通过黄体组织缺失和孕酮浓度低于1纳克/毫升确认所有母牛处于乏情期。尽管从实验开始（第0天）到卵泡波出现的平均（±标准误）间隔在各处理组之间没有差异（P>0.05）（对照组，1.9±1.0，范围 - 2至7天；CR组，3.9±0.7，范围0至6天；CIDR组，2.8±0.5，范围0至4天；CIDR + E - 17β组，4.1±0.2，范围3至5天），但CIDR + E - 17β组的变异性较小（P<0.05）。与CR组（5/8）或CIDR组（6/9）相比，CIDR + E - 17β组的母牛在GnRH给药后24至48小时排卵的比例趋于更高（P = 0.08）（8/9），并且与在GnRH处理时处于生长/早期静止期的优势卵泡比例更高（P<0.05）相关，相比之下，其他GnRH处理组（CR组和CIDR组分别为5/8和4/9）。2头CR组母牛在GnRH给药后0 - 24小时排卵，只有1头对照组母牛在GnRH给药前一天排卵。用孕酮预处理的母牛黄体寿命更长（P<0.05）（CIDR组，14.5±0.7，CIDR + E - 17β组，13.9±0.6天），比未用CIDR处理的母牛（对照组，5天，CR组，4.0±0.4天）长。我们得出结论，孕酮加雌二醇处理可使产后肉牛的卵泡波出现紧密同步，GnRH诱导的排卵率高，且黄体活动正常。
