by Dr. R. Dean Scoggins, Emeritus Professer, College of Veterinary Medicine, University of Illinois
Pasture breeding is a viable option for a number of horse breeders. Pasture breeding is still used extensively on western ranches and in Canada. PMU (pregnant mare urine) ranches utilize pasture breeding almost exclusively.
The advantages of pasture breeding include less labor and less supervision - just turn the stallion out and let nature takes its course. Documented serious injuries are relatively few. Stallions and some mares may acquire abrasions; both bite and kick marks may occur. The number of mares that can be bred to a single stallion is often restricted to 20-25. Many stallions breed fewer mares than this anyway. A real advantage is that conception rates are often improved over those of stallions hand covered and especially via AI and/or shipped (cool) or frozen semen. The mare and stallion decide on the optimal time for breeding to occur--normally when ovulation is imminent.
There are some basic requirements to minimize injuries and optimize breeding outcomes. Pens or pastures should be safely fenced. Rounded corners and an avoidance of any obstacles or potential traps are important. Other horses should not be in adjacent pens. There should be no direct horse to horses contact across fences. Enough space is necessary to allow horses sufficient room to get away from aggressive horses. Open pastures are best. All horses should be barefooted and have their hooves trimmed prior to turning the stallion into the pasture.
Mares selected for pasture breeding need to be of good reproductive conformation and free of contagious or infectious reproductive disease. Stallions should have a complete fertility exam prior to breeding to maximize the chances of getting mares pregnant.
The mares should be selected, run together as a group long enough that the pecking order is established (dominance hierarchy) before the stallion is turned in. Once the herd is established and the stallion turned in, do not add outside mares. Often the stallion will run the added mare off, even if she is in full estrus. If it is necessary to add a mare, remove the stallion, turn the new mare into the band and wait several days for her to find her place. Then re-introduce the stallion.
Inexperienced stallions can best be introduced by selecting an experienced mare with a quiet disposition. She should be in full standing heat. Turn the mare into a large, safely fenced paddock free of obstacles. Placing hay in the center acts as a distraction and may prove useful. Turn the stallion in and keep them under observation. Be certain that no halters or neck straps are left on either horse. Leave them together until the mares go out of heat. In this way, an inexperienced stallion will learn that mares are not receptive all of the time.
When loose, stallions and mares meet nose-to-nose. Squealing and striking often accompany this first meeting. Stallions will attempt to mount in the area of the front quarters initially. It's a safer position if the mare changes her mind. By not being restrained the mare can leave if she resists the stallion's advances. The mare can also move forward out from under the stallion once copulation has occurred. Many stallions have been hurt, some fatally, by backing a stallion off a mare following hand breeding.
Leave the stallion with the mares until they have had time to fully pass through two successive heat cycles - 45-60 days. Pregnancy check all of the mares 35-45 days after removing the stallion. Observe and maintain records when the stallion is observed servicing a mare.
Mares with foals can usually be pasture bred safely. Most stallions will not bother a mare's foal. It is important to provide sufficient space, thereby allowing room to avoid aggressiveness.
Basic health care, deworming and immunizations, plus proper feeding practices need to be maintained.
While pasture breeding is not for everyone, some breeders can use it to a real advantage. Consider the possibility in the right setting.
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