How often does a mare come into heat per year?

Mares have a natural reproductive cycle known as estrus. The normal estrus cycle lasts about 21 days, but can vary individually. A mare can be in estrus for about seven to nine days on average. Under normal conditions, several estrus periods occur throughout the year. The exact frequency can depend on factors such as time of year, light conditions, and individual differences. It is important to monitor the mare's cycle, especially if she is being used for breeding, to determine the optimal time for mating.