Breeding Truths & Folklore, PT 2

Yesterday My Stable Life featured two common breeding debates and with the help of Dr. Chris Berezowski, determined if they were myth or folklore. Today we continue the discussion…

3. Mares can display estrus behavior during pregnancy.

“Yes, this can definitely happen,” proclaims Dr. Berezowski. Unfortunately, when it does happen it can startle the mare owner, especially if the person is new to the breeding game. “The reason for that is because during pregnancy, progesterone is the main hormone responsible for keeping the mare in her pregnancy. Then, the placenta is producing high levels of estrogen which can cause mares to act like that. The signs the mare displays that borderline true heat are due to the high levels of estrogen produced.”

A pregnant mare is actually capable of winking, peeing, squealing and displaying strong signs of heat despite being late in gestation.

4. Breeding stallions should be housed with other stallions.


“There aren’t any negatives to harem housing,” said Dr. Berezowski, referring to the practice of stabling stallions with mares directly around them. “The only concern would be if the horses weren’t behaving themselves. Harem housing actually poses some benefits for a stallion because he’s always having a bit of stimulation. If you have two studs across the aisle from each other, one may be more dominant than the other. Of course, this all depends on the studs but if there is a weaker, more submissive stallion, as a result of being housed next to a more dominant stallion, he will have lower testosterone levels.”

5. Breeding via live cover is best.


Many people think conception rates are improved with live cover, the act of mating between a stallion and mare, either through pasture breeding or hand-breeding. Although your odds for conception are excellent with live cover, your chances are as good, or nearly as good, with artificial insemination and frozen semen because today’s technology is becoming so advanced.

“And truthfully, you can’t say conceptions are the same across the board with every stallion,” Dr. Berezowski begins. “Even with live cover because some need the extra collection. Or they must have extender added, etc. Some really need to be centrifuged.”

Dr. Berezowski states that a normal, average stallion would probably produce his highest number of progressively motile sperm with live cover, at any one time. There may be a slight decrease with semen collected for artificial insemination, but generally, both should be on par.

“If however, you collect him and cool his semen for 24 hours, or freeze it, you will definitely have a decrease with that,” he says.

Chris Berezowski is an equine reproductive specialist at Moore & Co. veterinary clinic in Balzac, Alberta. He received specialty training at Texas A &  M University and prior to that, went to the Western College of Veterinary Medicine in Saskatoon, Saskatchewan.


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