U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Published in Beef Research Program Progress Report (1993) No. 4 (Part 1): 96-98


Of the two methodologies utilized in the beef industry to synchronize animals to estrus (prostaglandin regression of the corpus luteum or implanting/injecting progestin which results in estrus 48-60 hr after implant removal), conception and fertility are generally lower in progestin synchronization to estrus. Both technologies produce comparable results in relation to estrus and ovulation. Alterations in steroidal hormones of the follicle (progesterone/estradiol) are important in the maturation and quality of oocytes. Insulin-like growth factor (IGF-I) which can regulate follicular progesterone concentrations, may have a role in oocyte maturation and viability. Circulating progesterone concentrations alter luteinizing hormone (LH) pulse frequency and amplitude and possible oocyte maturation as LH is the primary hormonal initiation of the ovulatory process. The objectives of this study were to monitor the difference in oocyte quality and follicular steroids in relation to the two methods of estrous synchronizatjon.