University of wisconsin-madison

Embryo Transfer: Selection of the Donor Mare

Subfertile Mares

Since ET is expensive, it is important to select the donor mare carefully. Embryo transfer will not solve infertility problems associated with the quality of the oocyte (aged mares) or mares with oviduct blockage or disfunction. Mares however which have repeated early embryonic death (uterine environment), endometrial periglandular disease or repeated unexplained abortion are good candidates for ET.

Superior Mares

Genetically supperior mares may be selected for ET because they can have more than one foal per year depending on breed registry requirements. A mare might also be bred to multiple stallions during one breeding season producing foals from each of the breedings. For example, the first breeding might be to a Quarter horse mare bred to a paint stallion and the foal registered in American Paint Horse Association. The second breeding might then be the Quarter horse mare bred to Quarter horse, with the foal registered in the American Quarter Horse Association. It is also possible for a mare to have a foal early in the season by ET and then later be bred to carry her own foal.

Since performance mares only need to take 1-2 weeks off to donate an embryo for ET these have also become the type of mare selected for ET. For example polo horses routinely compete yet donate embryos after the competition season. The mare can thus have a foal yet be able to compete next year in her sport.

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