For all things there is a time and a season. Nowhere is this more true than in equine reproduction. Nature has established a definite time and season for mares to conceive and bear foals. It is a very sensible approach on the part of Mother Nature. The mare is most fertile and receptive to a stallion in the warming days of late spring and early summer. Because of her 11-month gestation period, this means that, if bred during that period, she will give birth to a foal when the grass is green and the sun is warm upon the Earth.

So much for what Mother Nature has dictated. Man, through the years, has had other ideas.

The purpose of this primer is not so much to discuss man’s tinkering with equine reproduction as it is to provide basic information on a mare’s normal estrous cycle. To begin at the beginning, we must first discuss the physical makeup of this complicated, but sometimes effective reproductive system