Hormonal induction of estrous cycles in anestrous Bos taurus beef cows.

A significant proportion of postpartum beef cows are anestrus at the onset of the breeding season. Much progress has been made in understanding anestrus and the changes that lead to spontaneous resumption of reproductive function. Likewise, knowledge regarding the impact of hormonal interventions on the endocrine and ovarian changes normally associated with spontaneous resumption of estrous cycles continue to accumulate. A wide range of hormonal treatment programs designed to induce estrous cycles in anestrous cows to coincide with the start of the breeding season have been developed. Programs structured to provide for increased progesterone, estradiol and LH concentrations at the appropriate times during the period leading to the first ovulation, and an induced preovulatory gonadotropin surge when the dominant ovarian follicle is of appropriate maturity have been demonstrated to induce estrous cycles of normal duration and acceptable fertility in a majority of anestrous, Bos taurus beef cows.