If you hope to breed your open or maiden mare in the late winter or early spring, she needs to go under artificial lights. Mares started under lights on December 1 will likely begin cycling by mid-February. Horsemen have used this lighting trick for decades. Essentially, the additional light prompts the mare’s hormonal system into believing it’s spring.
Natural Cycles
In the fall, the decreasing daylight hours signal the mare’s pineal gland to secrete more melatonin, a hormone that suppresses ovarian activity. During the winter, there is very little follicular activity, with minimal estrogen and progesterone, resulting in no heat cycles.
As daylight increases in the spring, less melatonin is secreted and mares transition back to cycling. During that transition period, the heat cycle is irregular.
When a mare is placed under artificial lights, melatonin production is reduced, the transition occurs and regular heat cycles resume. It takes about 30-45 days of increased daylight for mares to make the transition, and another 20 days or so for mares to go through a heat cycle.
Consistency is Key
The good news for breeders is that putting a mare under lights is relatively easy. Begin December 1 by supplementing the daylight in your horse’s stall or paddock with artificial lighting, for a total of 16 hours of light each day.
Keep in mind that light must enter your horse’s eyes in order to stimulate the hormonal system. There can be no dark corners in her stall or paddock. The classic rule of thumb is that you should be able to read a newspaper in every nook and cranny of the lit area. For reference, the mares at Iron Spring Farm are under 100-watt incandescent bulbs.
The key to a lighting program’s success is consistency. Even a few days of missing 16 hours of daylight may prevent your mare from early cycling. Consider keeping your lights on timers to ensure accuracy, remembering to adjust them as the amount of natural daylight changes. Your mare will need to stay under lights until she is bred, or until actual daylight runs 16 hours daily.
Another result of the artificial lighting program is that your mare will shed, so be prepared for additional blanketing.
While it does take some planning and effort, putting your mare under lights increases your opportunity to get your mare in foal.
Disclaimer:
All content provided by Iron Spring Farm is general and for informational purposes only. Content may also not constitute the most up to date information. Nothing in this content is intended to constitute veterinarian advice or to serve as a substitute for consultation with a veterinarian. Always seek the advice of your veterinarian or other qualified provider with any questions that you may have about the treatment and care of your horse.
Any reliance that you place on the information provided is strictly at your own risk and Iron Spring Farm, its officers, employees, representatives, and agents, hereby disclaim any and all liability to any party for any direct, indirect, implied, punitive, special, incidental, consequential or other damages arising directly or indirectly from access to or use of any content provided to the maximum extent permitted by law.
Disclaimer:
All content provided by Iron Spring Farm is general and for informational purposes only. Content may also not constitute the most up to date information. Nothing in this content is intended to constitute veterinarian advice or to serve as a substitute for consultation with a veterinarian. Always seek the advice of your veterinarian or other qualified provider with any questions that you may have about the treatment and care of your horse.
Any reliance that you place on the information provided is strictly at your own risk and Iron Spring Farm, its officers, employees, representatives, and agents, hereby disclaim any and all liability to any party for any direct, indirect, implied, punitive, special, incidental, consequential or other damages arising directly or indirectly from access to or use of any content provided to the maximum extent permitted by law.
