Estrous Cycle
The estrous cycle of the mare is defined by behavioral changes. It begins with 7 days of estrus and is followed by 14 days of no estrus or diestrus. In general ovulation or release of the oocyte from the ovary will occur the day before a mare goes out of estrus. The estrous cycle therefore lasts for 21 days and will continue to be repeated during the breeding season until a mare becomes pregnant.
The estrus cycle of the mare can be summarized as:
- 21 day cycle
- 7 day estrus (heat, sexually receptive)
- 14 day diestrus
- Ovulation occurs the day before going out of estrus
Note that the term estrus refers to the behavior associated with receptivity to the male. The term estrous however is used to describe the entire length of the cycle.
