Studies on Improvement of Reproductive Efficiency in Goats

ABSTRACT

This study was carried out to improve reproductive efficiency in goats through induction of estrus outside the breeding season and increasing ovulation rate. According to our results, estrus can be induced in seasonally anestrous Egyptian Baladi goats by using norgestomet and PGF_2a and the injection of GnRH synchronized ovulation in a higher percentage of goats. We used transrectal ultrasonography for investigation of the reproductive tract to gain knowledge of follicular and luteal development on the ovaries during the estrous cycle and correlate follicular dynamics with hormonal profile. The results demonstrated that follicular waves occurred in goats and the predominant follicular wave pattern was 4 waves with ovulation from wave 4. These results also suggested that the follicular waves’ emergence was closely associated with increased secretion of FSH.

In a trial to make superovulation in goats using new techniques, two experiments were carried out to explore the effects of active and passive immunization against inhibin on circulating gonadotropins, estradiol, progesterone levels and ovulation rate. The results demonstrated that inhibin immunization increased FSH concentrations. In addition, immunization of goats against inhibin resulted in increase in ovulation rate. An approximately four-fold increase in ovulation rate in case of active immunization and two-fold increase in case of passive immunization. These observations confirm a physiological role of inhibin as a regulator of FSH secretion in goats and enhanced ovarian follicular development and ovulation rate by promoting increase in pituitary FSH secretion. Therefore, immunization against inhibin could be used to generate increases in litter size or increased numbers of oocytes and/or embryos for multiple ovulation-embryo transfer programs. The early determination of pregnancy can be used as a useful management tool in improving reproductive efficiency. Pregnancy diagnosis will identify the females which require repeat breeding or insemination and will allow separation of pregnant and open females for differential management. The results demonstrated that ultrasound is a reliable and safe method for pregnancy diagnosis in goats. Gestational sac could be first detected at day 20.2 ± 0.6 of gestation and embryos could be detected at 24.3 ± 0.7 days of gestation.