Plan for Success when Breeding with Frozen-Thawed Semen

Their long period of pregnancy means that mares can produce only one foal per year, so breeders want to ensure that every mare has the best possible chance to get in foal during the breeding season. Choosing a stallion that has a successful record with frozen-thawed semen is important, but breeders need to put an equal amount of consideration into selecting mares that have the best likelihood of conceiving with this method of artificial insemination.

Age of the mare is one of the most important factors, with young mares generally having the best fertility rates. A maiden mare that is younger than eight is the best choice, followed by young mares that have had successful pregnancies in the past. Older mares, those that have not been bred in a number of years, and those that have previously had any fertility problems are less likely to do as well.

Almost all mares show some degree of uterine inflammation after natural or artificial breeding, and this condition usually clears up without treatment within a few days. This reaction is naturally more pronounced in some mares than in others. The use of frozen-thawed semen tends to produce an increased inflammatory response, possibly because some of the sperm cells rupture during the preservation process and this produces intracellular material that normally would not come in contact with the uterine lining. In any case, post-breeding uterine inflammation that is more severe or longer-lasting than usual is detrimental to fertility, so mares that have shown an increased inflammatory response in the past are not the best choices for the use of frozen-thawed semen.

As any breeder has learned from experience, mares who seem to be the best prospects will sometimes fail to conceive time after time, and mares with many strikes against them can prove to be the most consistent producers. However, evaluating mares as to their likelihood of being able to become pregnant and carry a foal to term is a helpful management step before using frozen-thawed semen. If the chosen mare seems to have issues that may impact her fertility, consult with a veterinarian several months before the planned breeding date to clear up or minimize problems before breeding with this method.