Cows received a progesterone-releasing intravaginal device and 2 mg estradiol benzoate on the first day of the protocol for synchronization of ovulation.
The implant was removed 8 d later, with or without the administration of eCG (equine chorionic gonadotropin = 0, 400 or 600 IU). Prostaglandin 2 was
administered in all cows. After 56 h timed artificial insemination (TAI) was performed concurrent with the administration of GnRH (Study 1) or after 48 h
GnRH was administered and TAI was performed 8 h later (Study 2).