Physiology related to the use of eCG in beef and dairy cattle

Equine chorionic gonatrophin (eCG) is a high molecular weight glycoprotein produced by endometrial cups in the mare. ECG has primarily LH activity in the mare, but has FSH or LH activity in the cow, depending on the recipient populations in the ovary. Although eCG has been used to induce superovulation in a variety of species, several studies have demonstrated the beneficial effects of eCG on fixed-time AI (IATF) programs in beef and dairy cattle, and embryo recipients. Under these circumstances, eCG has stimulated the development of the ovulatory dominant follicle and produced ovulation of a larger follicle, resulting in a larger and more functional LC and longer embryo survival. In suckling beef cows, 400 IU of eCG at the time of removal of a progesterone device resulted in increased conception rates after IATF,and in dairy cattle managed in pastoral systems, the eCG administration resulted in a significant increase in pregnancy rates, especially in cows in anestrus. In embryo recipients, treatment with eCG has resulted in increased pregnancy rates after embryo transfer. This presentation will review some of this data and explore strategies to use the potential benefits of eCG to improve bovine reproduction.