Synchronization of Estrus and Ovulation in Bovine Embryo Transfer Recipients

Traditional methods of estrus synchronization developed over the past 60 yr have involved controlling bovine estrous cycle length by administering a progestin and/or regressing the corpus luteum with luteolytic drugs. The synchrony of estrus and timing of ovulation following traditional estrus synchronization treatments has been too variable to allow the transfer of a fresh or frozen/thawed embryo without estrus detection. Synchronization treatments developed more recently, however, combine traditional methods of controlling cycle length with the manipulation of follicular development in order to “program” or “select” the ovulatory follicle. The new methods synchronize estrus more precisely and control the time of ovulation more exactly. These treatments may control ovulation with enough repeatability and precision to insure synchrony of estrous cycles of ET recipients without the need for visual estrus detection.