Ovaries of mares during the early transition period are characterized as small and hard with only small follicles. It is not until one follicle is selected to mature that the mare ovulates and a normal cycle is initiated. The erratic estrus behavior leads to low pregnancy rates during February and March. Normalization of the estrous cycle earlier in the breeding season would result in considerable savings in terms of time, labor, and stallion usage, and would improve reproductive efficiency. Another problem associated with equine breeding is the uncertainty of the time of ovulation.
Ovulation can occur at any time during estrus, but normally occurs at the end of the estrus period.
Much time is consumed by regular teasing to detect estrus behavior and by rectal palpation to determine the time of ovulation. When the teasing program has resulted in the mare showing signs of estrus, it is time for rectal palpation to aid in predicting the time of ovulation. For stallions which are heavily booked, it is imperative that the number of covers on individual mares be kept to a minimum. While teasing is imperative in detecting estrus, there are steps the mare owner can take to assure that the mare will come into estrus at an early date. A key element, declares Scott Bennett, DVM, who operates Equine Services in Simpsonville, Ky., is diet.