How to Decide When to Breed the Postpartum Mare
نویسنده
چکیده
One of the primary requirements for efficient and economically viable broodmare management is the production of a foal per year, in at least 6 years out of 7. Although this sounds relatively straightforward, the limitations of a long gestation period (mean of 335 to 345 days), a limited physiological breeding season (March to September) and, for some breeds, the extra restriction of an arbitrary covering season (eg, February 15 to July 1 for Thoroughbred racehorses in the northern hemisphere), leaves little margin for error. Since owners will generally want consecutive foals to be born at around the same time each year, there is effectively a period of only 1 month after foaling in which to establish pregnancy. On the other hand, the postpartum period of the mare is characterized by a very early first postpartum estrus (foal-heat) that typically begins 5 to 12 days after foaling. Although the foal-heat presents an early opportunity for breeding, it can result in the fertilized embryo entering the uterus before uterine involution is complete and when the ability to maintain pregnancy may be compromised. Therefore, the dilemma for owners and veterinarians is to decide if they should breed at the first postpartum estrus or if waiting for a subsequent heat (with or without pharmacological induction) offers the best likelihood of not only establishing but also maintaining pregnancy. Fortunately, the decision-making process can be assisted by using the history and an initial prebreeding clinical examination to determine whether or not a mare is a suitable candidate for foal-heat breeding. Clearly, the arguments will be different in situations in which embryo transfer is both permissible and considered a viable option by the mare owner.
منابع مشابه
response of lactating karakul ewes to two levels of exogenous estradiol 17.B along with progesterone and pregnant mare serum for induction of fertile estrus at early postpartum
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