Asked by Ansi van der Merwe
Mares can continue to produce foals well into their late teens and even into their early to mid-twenties. However, breeders should be aware that the fertility of mares decreases each year from around fifteen years of age. An older mare who has had a foal earlier in her life is more likely to become pregnant than an older mare who has not.
Peak fertility occurs between the ages of six and seven years old, and declines around the age of 15 years old. A young and healthy mare has a 50-60% chance of becoming pregnant when mated to a fertile stallion, whereas an older mare has a 30-40% chance.
Breeders must also be aware of an older mare’s health condition. A mare must be able to carry the weight of her foal during pregnancy, and certain leg conditions or particularly weak core musculature may not allow for this. A mare must be given a clean bill of health before breeding, whatever her age, so that there is no risk of health issues that could endanger the health of the mare or foal. However, this clean bill of health is even more important in older mares.