Spring is an exciting time of year with all the new foals, warmer weather, and more daylight. It’s also the time of year we breed our mares for next year’s foal crop.
Have you ever wondered why we breed mares in the springtime? As many of us know, mares are classified as seasonal breeders. Most of us have heard that mares need the increasing period of daylight (longer photoperiod) associated with spring before they will come into heat known as estrous. As the length of daylight increases, it stimulates the pineal gland within the brain. This stimulation results in a decreased production of melatonin which allows for the secretion of hormones that lead to estrous.
The photoperiod is a primary factor initiating estrous in the mare and consequently it gains most of the focus. Also very important in influencing estrous in mares is nutrition and climate. In my experience, conception rates are always highest in those mares with a Body Condition Score (BCS) of 5 or 6 on a scale of 1-10. This means the ribs are invisible, but readily palpable. Also noted, conception rates are lower when there are cold spring storms throughout the breeding season. Working in the Northern climate, this is also seen when using artificial lights to manipulate or “trick” the endocrine system of the mare in order to stimulate estrous. Increasing the photoperiod on a mare that is too thin or too heavy may or may not stimulate estrous. Inconsistent results also occur without the use of heated barns or blankets in the colder northern climates. However, if I am able to increase the photoperiod in a climate controlled barn with mares having a BCS of 5 or 6, I consistently produce estrous behavior greater than 90% of the time.
Breeding horses is not cheap; do your homework, have your mare in shape, and invest in a quality Breeding Soundness Exam performed by a qualified veterinarian. This will allow for a true assessment of your mare’s reproductive potential. Ensuring a reproductively healthy mare, choosing a fertile stallion, and a little help from Mother Nature will produce the horse of your dreams!
This tip was brought to you by Dr. John Smart, Belgrade, MT (406-209-6907) and KAM Animal Services, home of KAM’s “Equine Learning Circle” FREE webinars, which take place monthly. These webinars are an expansion of KAM’s weekly tips. Go to www.kamanimalservices.com to sign up for the next webinar. Upcoming webinars include “Get It in Writing” on May 16 and “Electrolytes, Detoxing and First Aid” on June 13. These webinars will conclude with a question and answer session, so be ready with your questions!