Importance of intense male sexual behavior for inducing the preovulatory LH surge and ovulation in seasonally anovulatory female goats

Abstract

The present study was carried out to determine whether the presence of photostimulated sedated male goats could stimulate the LH preovulatory surge and ovulation in seasonal anestrous goats. Sexually experienced male goats were treated with artificial long days (16 hours light per day) from 1 November to 15 January to stimulate their sexual activity in March and April, corresponding to the natural sexual rest. A female group of goats (n = 20) was exposed to non-sedated males who displayed an intense sexual behavior and provided strong odor (non-sedated group). Another female group of goats (n = 20) was exposed to the photo-stimulated male goats, but these males were sedated with Xylazine 2% to prevent the expression of sexual behavior (sedated group). The sedated males also provided a strong odor. Females of both groups had full physical and visual contact with non-sedated or sedated males. In both groups, the males remained with females during 4 days. The LH preovulatory surge of 10 female goats per group was measured by determination of LH plasma concentrations in samples taken every 3 hours. In addition, in all goats, (n = 20 by group), ovulation was determined by measuring plasma concentrations of progesterone. The proportion of female goats showing a preovulatory LH surge was higher in goats exposed to non-sedated (10/10) than in those exposed to sedated bucks (0/10; P < 0.0001). Similarly, most of does in contact with non-sedated males ovulated (19/20), but none of those in contact with sedated males did so (0/20; P < 0.0001). We conclude that the expression of an intense sexual behavior by male goats is necessary to induce LH preovulatory surge and ovulation in seasonally anovulatory goats.