Calderón-Leyva Guadalupe, Meza-Herrera Cesar A, Rodriguez-Martinez Rafael, Angel-García Oscar, Rivas-Muñoz Raymundo, Delgado-Bermejo Juan V, Véliz-Deras Francisco G
Universidad Autónoma Agraria Antonio Narro, Periférico Raúl López Sánchez y Carretera a Santa Fe, 27054 Torreón, Coahuila, Mexico; Universidad de Córdoba, Instituto de Estudios de Posgrado, Campus Rabanales, 14071, Córdoba, Spain.
Universidad Autónoma Chapingo, Unidad Regional Universitaria de Zonas Áridas, Bermejillo, Durango 35230, Mexico.
Theriogenology. 2018 Jan 15;106:79-86. doi: 10.1016/j.theriogenology.2017.10.016. Epub 2017 Oct 9.
The aim of this study was to determine if exogenous administration of glutamate and (or) testosterone to male rams during the season of reproductive arrest is able to re-activate male sexual behavior and, later on, to promote through the male effect, both sexual and reproductive competence of anovulatory nulliparous ewes. Therefore, an experiment was performed under long-day photoperiods (spring; photo-reproductive arrest, 26°N). Dorper rams were randomly divided into four homogeneous experimental groups (n = 5 males each) regarding live weight (LW), body condition score (BCS), scrotal circumference (SC) and odor intensity (OI). Then, groups were treated with: i) GG (7 mg kg LW of glutamate, every 4d × 30d, im.), ii) GGT (7 mg kg LW of glutamate every 4d × 30d im + 25 mg of testosterone propionate, every 3d × 15d, im.), iii) GT (25 mg of testosterone propionate every 3d × 15d, im, and iv) GC (1 mL of saline, every 4d × 30d, im.). Thereafter, Dorper rams, (n = 4 per group) were selected and exposed to Dorper anovulatory-nulliparous ewes divided in four groups (n = 14 ewes each), and all the appetitive (ASB) and consummatory (CSB) sexual behaviors and indicators of sexual rest (ISR) were registered during the first 48 h of this male-to-females contact. Thereafter, males continued the male-to-female contact for another 8 d, in order to quantify the ewe's sexual and reproductive response through the male effect. During the sexual behavior tests, the GGT rams showed the highest ASB + CSB frequencies (P < 0.05) followed by the GG-rams with the lowest frequencies showed by the GC and GT groups. While the highest ISR behaviors were shown by the GG and GGT groups (P < 0.05) followed by the GC and GT-rams, no differences occurred regarding LW, BCS, and SC along the experimental breeding, with the largest (P < 0.05) OI shown by the GGT-rams and the lowest value observed in the control rams. Regarding the reproductive response of the nulliparous-anovulatory ewes exposed to treated rams, the glutamate + testosterone treated males induced not only an increased (P < 0.05) ovulatory activity and faster (P < 0.05) estrus response but an augmented (P < 0.05) pregnancy rate of the previously anovulatory ewes. To conclude, whereas the GG and GGT treatments generated encouraging sexual and reproductive outcomes, our results are also thought-provoking from a comparative sexual behavior perspective while may embrace potential applications to other animal industries.
本研究的目的是确定在繁殖停滞季节向雄性公羊外源施用谷氨酸和（或）睾酮是否能够重新激活雄性性行为，并随后通过雄性效应促进无排卵未生育母羊的性能力和生殖能力。因此，在长日照光周期（春季；光繁殖停滞，北纬26°）下进行了一项实验。根据体重（LW）、体况评分（BCS）、阴囊周长（SC）和气味强度（OI），将杜泊公羊随机分为四个同质实验组（每组n = 5只雄性）。然后，各组分以下处理：i）GG组（每4天肌肉注射7 mg/kg体重的谷氨酸，共30天），ii）GGT组（每4天肌肉注射7 mg/kg体重的谷氨酸，共30天 + 每3天肌肉注射25 mg丙酸睾酮，共15天），iii）GT组（每3天肌肉注射25 mg丙酸睾酮，共15天），iv）GC组（每4天肌肉注射1 mL生理盐水，共30天）。此后，挑选杜泊公羊（每组n = 4只）并使其与分为四组（每组n = 14只母羊）的杜泊无排卵未生育母羊接触，并在这种公母接触的前48小时记录所有求偶性行为（ASB）、交配性行为（CSB）和性静止指标（ISR）。此后，雄性继续与雌性接触另外8天，以便通过雄性效应量化母羊的性反应和生殖反应。在性行为测试中，GGT组公羊的ASB + CSB频率最高（P < 0.05），其次是GG组公羊，GC组和GT组频率最低。GG组和GGT组表现出最高的ISR行为（P < 0.05），其次是GC组和GT组公羊，在整个实验繁殖过程中LW、BCS和SC方面没有差异，GGT组公羊的OI最大（P < 0.05），对照组公羊的OI值最低。关于接触经处理公羊的未生育无排卵母羊的生殖反应，谷氨酸 + 睾酮处理的雄性不仅诱导排卵活性增加（P < 0.05）和发情反应更快（P < 0.05），而且使先前无排卵母羊的妊娠率提高（P < 0.05）。总之，虽然GG组和GGT组处理产生了令人鼓舞的性和生殖结果，但从比较性行为的角度来看，我们的结果也发人深省，同时可能对其他动物产业具有潜在应用价值。
