Tejada Luz M, Meza-Herrera Cesar A, Rivas-Muñoz Raymundo, Rodríguez-Martínez Rafael, Carrillo Evaristo, Mellado Miguel, Véliz-Deras Francisco G
Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, 27054, Torreón, Coahuila, Mexico.
Unidad Regional Universitaria de Zonas Áridas, Universidad Autónoma Chapingo, 35230, Bermejillo, Durango, Mexico.
Arch Sex Behav. 2017 Apr;46(3):835-842. doi: 10.1007/s10508-016-0852-x. Epub 2016 Sep 14.
We determine whether Dorper rams treated with testosterone in the sexual resting season trigger both appetitive and consummatory sexual behaviors and sexual and reproductive outcomes in anestrous ewes at 26° North during March-April. Dorper rams (n = 12, 2.5 years) were randomly divided prior to mating in two groups: GT (treated group; n = 6), treated with testosterone propionate (25 mg i.m. every 3 days × 3 weeks) and GC (control group; n = 6), treated with saline. Thereafter, adult anovulatory Dorper ewes (n = 61) were exposed to the GT-rams while the other group (n = 60) was exposed to the GC-rams. Ram's appetitive sexual behavior was similar (50 %) in both groups, yet the GT-rams exerted 100 % of the consummatory sexual behavior. Sexual and reproductive outcomes of the anestrus females exposed to both male groups considered two phases: 0-15 and 16-25 days from exposure to males. Involved variables were: ewes in estrus, ewes ovulating, duration of estrus, pregnant ewes, and lambed ewes. All the average variables favored those ewes exposed to GT-males: ewes in estrus: 85 versus 40 %; ewes ovulating: 80 versus 53 %; duration of estrus: 37 versus 25 h; pregnant ewes: 60 versus 31 %, and lambed ewes: 57 versus 31 %. Results confirm that adult Dorper rams treated with exogenous testosterone had improved consummatory sexual behavior and induced increased ovulation and pregnancy rates when exposed to anestrus ewes. This feasible and inexpensive testosterone-based protocol through the male effect also enhanced both sexual and reproductive outcomes in previously anestrous Dorper ewes during the natural out-of-season. Results are important to speed up reproductive performance of sheep during the natural anestrous season at this latitude, while also they embrace interesting outcomes from a comparative sexual behavior stand point.
我们研究了在性休止期用睾酮处理的杜泊公羊，是否能在3月至4月北纬26°的季节，引发处于发情间期的母羊的求偶和交配性行为以及性和生殖结果。在交配前，将12只2.5岁的杜泊公羊随机分为两组：GT组（处理组；n = 6），每3天肌肉注射25毫克丙酸睾酮，共3周；GC组（对照组；n = 6），注射生理盐水。此后，将61只成年无排卵的杜泊母羊与GT组公羊接触，另一组60只母羊与GC组公羊接触。两组公羊的求偶性行为相似（50%），但GT组公羊的交配性行为占比为100%。接触两组公羊的发情间期母羊的性和生殖结果分为两个阶段：从接触公羊开始的0至15天和16至25天。涉及的变量有：发情母羊、排卵母羊、发情持续时间、怀孕母羊和产羔母羊。所有平均变量都有利于接触GT组公羊的母羊：发情母羊：85%对40%；排卵母羊：80%对53%；发情持续时间：37小时对25小时；怀孕母羊：60%对31%；产羔母羊：57%对31%。结果证实，用外源性睾酮处理的成年杜泊公羊，在与发情间期母羊接触时，其交配性行为得到改善，排卵和怀孕率增加。这种基于睾酮的可行且低成本方案，通过雄性效应，也提高了自然非繁殖季节中先前处于发情间期的杜泊母羊的性和生殖结果。这些结果对于加快该纬度自然发情季节绵羊的繁殖性能很重要，同时从比较性行为的角度来看也包含了有趣的结果。
