Periovulatory Hormonal Profiles after Estrus Induction and Conception Rate by Fixed-Time AI in Payoya Goats during the Anestrous Season

SIMPLE SUMMARY: Standardized induction and synchronization treatments and AI timing are used in goats, despite the fact that physiological differences can be linked to the breed, which could compromise the achievement of the AI programs in autochthonous breeds. However, few, if any, studies have been carried out to explore the reproductive physiology in the autochthonous breeds, in contrast to the commercial breeds. We studied the periovulatory hormone-release in Payoya goats, an autochthonous, endangered Spanish breed, and some differences were detected between the pregnant and non-pregnant goats. We observed a lower LH peak in those goats that failed to get pregnant, whilst other periovulatory hormones showed a similar release pattern in both groups. The results suggest that the LH peak should be favored to increase the success of fixed-time artificial insemination programs, and further studies should be conducted to understand the cause of this diminished LH release during the preovulatory surge. ABSTRACT: Sexual activity in domestic goats is positively influenced by reducing the photoperiod. Various protocols have therefore been developed in goats for the induction and synchronization of estrus during those months in which their sexual activity is reduced. The present observational study evaluates the periovulatory hormonal profile in Payoya goats (n = 24), during a non-favorable photoperiod (i.e., spring), being treated for estrus induction. The treatment comprised the vaginal insertion of sponges impregnated with progestogen (fluorogestone acetate, FGA), together with cloprostenol and equine chorionic gonadotrophin (eCG), 48 h before the end of the treatment. When the treatment ended, the plasma concentrations of the LH, FSH, progesterone and estradiol were determined. The goats were inseminated 46 h after the sponge withdrawal, and a pregnancy diagnosis was carried out 40–45 days after the insemination. Various parameters were monitored, such as the peaks of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and estradiol, and their respective intervals, in reference to the time of the sponge withdrawal. The conception rate was 62.5%, and the kidding rate was 50%. The results record the hormonal release pattern after the estrus synchronization treatment based on the FGA, and the differences between the pregnant and non-pregnant goats. The findings suggest that the LH peak produced after the estrus synchronization treatment, both in terms of the amplitude and the time of increment, is involved in the reproductive failure detected.