Seasonal variation in sexual behavior, plasma testosterone and semen characteristics of Argentine Pampinta and Corriedale rams.

摘要

Five Argentine Pampinta (dairy breed) and six Corriedale (dual-purpose breed) adult rams were used to study the effect of season on sexual behavior, plasma testosterone (T) and semen characteristics for a period of 1 year. Scrotal circumference (SC) and T concentrations were determined at 2-week intervals. Each ram was exposed monthly to three ovariectomized ewes in one 20-min test and the total number of mounts and successful matings were recorded. Semen collection was attempted from each ram twice weekly for six consecutive weeks during each season. In both breeds, SC varied seasonally showing the lowest mean values during winter and spring and in the Corriedale rams (32.8+or-0.3 cm) was smaller (p<0.05) than in Pampinta rams (34.4+or-0.4 cm). No difference (p