What's new in timed artificial insemination and assisted reproduction in beef cattle?

Abstract

Protocols designed to control follicular wave dynamics and ovulation in cattle have reduced, and even eliminated, the need for estrus detection. The addition of progestin-releasing devices and gonadotropin treatments, such as equine chorionic gonadotropin, have provided possibilities for increased pregnancy rates, especially in cows experiencing postpartum anestrus. In embryo transfer programs, these same treatment protocols have again eliminated the need for estrus detection, permitting fixed-time embryo transfer. In superovulation schemes, the control of follicular wave emergence and ovulation has also eliminated the need for estrus detection in donors, facilitating donor management. Alternative approaches to control follicular wave emergence have been developed recently by increasing the responsiveness of donors to gonadotropin releasing hormone. To further simplify superstimulatory treatments, follicle stimulating hormone has been diluted in a hyaluronan-based, slow-release formulation permitting the induction of superovulation with only two intramuscular injections. Collectively, new treatment protocols have facilitated the widespread application of artificial insemination and embryo transfer in beef cattle, primarily by eliminating the necessity of estrus detection.