What is Embryo Transfer? It is the process of breeding a donor mare, removing the fertilized egg from her and placing the embryo in a recipient mare to carry. The recipient mare produces the foal and raises it as her own. The genetic mare's name appears on the papers as the dam. Many Clubs and Associations have agreed to register more than one foal per year out of a single mare to allow for embryo transfers. Cows can be superovulated to produce more eggs. This cannot be done for
horses. A mare's reproductive system limits the number of eggs she can produce each heat cycle. Approximately 2.5 embryos can be produced each year from one mare. Embryo transfers are meant for mares in training, mares that abort or typically have late foaling dates, or older mares with fertility problems. Performance mares can take a break in training to be bred, have an embryo transferred and continue training. Mares that are settled, then abort can now use embryo transfer for producing foals. If the foal is carried past 25 days, the chances of it working are greater. Embryo transfer is not for every breeder, or for every mare. But embryo transfer allows breeders the opportunity for breeding that was not possible in the past.