Miguel-Cruz Erika Elizabeth, Mejía-Villanueva Octavio, Zarco Luis
Ovine Teaching and Research Farm, Faculty of Veterinary Medicine, National Autonomous University of Mexico, Tres Marias, Morelos 62515, Mexico.
Asian-Australas J Anim Sci. 2019 Nov 1;32(11):1673-1685. doi: 10.5713/ajas.18.0769. Epub 2019 Apr 15.
To evaluate the efficacy of treatments based on GnRH, GnRH-PGF2α, and/or intense exposure to novel rams to induce fertile estrus without the use of steroid hormones in seasonally anestrous Suffolk ewes.
In the first experiment, ewes were treated with one injection of GnRH, two injections of GnRH administered 7 days apart, or a sequence of GnRH-PGF2α-GnRH. In the second experiment anestrous ewes were exposed, for 36 days starting on the day of weaning, to groups of four rams of three different breeds that were alternated every day. Besides exposure to the males, the ewes were injected with saline solution (ME group, n=20), with GnRH (ME-GnRH group, n=20) or with a sequence of GnRH-PGF2α-GnRH (ME-GPG group, n=20). The rams used for male-effect were fitted with aprons to prevent mating, and ewes detected in estrus were bred to selected fertile rams. Ovarian activity was monitored by progesterone determinations in both experiments.
In the first experiment sustained induction of ovarian activity was not achieved and no ewe was detected in estrus. In the second experiment induction of sustained ovarian activity was achieved in all groups. Most of the ewes were detected in estrus, 76.7 % of the ewes were mated during a 36-d breeding period and 71.7 % of all the ewes became pregnant during that period. No significant differences between groups were found for any of these variables. However, estrus detection efficiency was higher in the ME-GnRH group than in the ME group (p<0.05).
An intense male-effect, that included the continuous presence and frequent alternation of several rams of different breeds, was sufficient to induce ovarian activity and fertile estrus in Suffolk ewes during the period of deep anestrus without the use of hormones, although addition of GnRH improved the efficiency of estrus detection.
评估基于促性腺激素释放激素（GnRH）、GnRH - 前列腺素F2α（PGF2α）和/或强烈接触新公羊，在不使用类固醇激素的情况下诱导季节性乏情萨福克母羊出现可育发情的治疗效果。
在第一个实验中，母羊接受一次GnRH注射、间隔7天的两次GnRH注射，或GnRH - PGF2α - GnRH序列注射。在第二个实验中，从断奶当天开始，乏情母羊连续36天暴露于三组不同品种的四只公羊组成的群体中，公羊每天更换。除了接触公羊外，母羊分别注射生理盐水（ME组，n = 20）、GnRH（ME - GnRH组，n = 20）或GnRH - PGF2α - GnRH序列（ME - GPG组，n = 20）。用于产生雄性效应的公羊佩戴围裙以防止交配，检测到发情的母羊与选定的可育公羊配种。在两个实验中均通过测定孕酮来监测卵巢活动。
在第一个实验中未实现卵巢活动的持续诱导，未检测到发情母羊。在第二个实验中，所有组均实现了持续卵巢活动的诱导。大多数母羊被检测出发情，76.7%的母羊在36天的配种期内交配，在此期间所有母羊中有71.7%怀孕。这些变量在各组之间均未发现显著差异。然而，ME - GnRH组的发情检测效率高于ME组（p＜0.05）。
强烈的雄性效应，包括几只不同品种公羊的持续存在和频繁更换，足以在深度乏情期诱导萨福克母羊的卵巢活动和可育发情，且无需使用激素，尽管添加GnRH可提高发情检测效率。
