Embryo Transfer is the act of removing a 6-8 day embryo from the uterus of a donor mare and transferring that embryo into the uterus of a recipient mare. This process requires that mares are cycled in parallel so that hormonal levels are consistent in both mares. Donor mares can be as young as 3 years of age. EPVP staff members are experienced in transferring embryos and have been doing so for over 10 years.
The benefits of embryo transfer are well known. Valuable mares can produce multiple embryos in one season. Performance mares can continue competing and transfers can be done around their show career. Fertility of older mares may be impaired, reducing the chances of getting in foal. Embryo transfer is often used to produce foals from these mares and allow the genetic potential of the mares to be continued. Mares unable to carry their own foals to term (various reasons: such as lameness issues, cervical tears, systemic health conditions that preclude pregnancy) are also good candidates for embryo transfer. Embryo transfer can be used on mares late in the season so the next year the mare can be bred earlier. Embryos can be recovered from mares with uterine based infertility issues. Additionally, embryos can be frozen and shipped over-seas allowing horse owners to reach new markets around the world.
The recipient mare (the mare the embryo is transferred into) is arguably one of the most important factors in an embryo transfer program. The ideal recipient mare is 3-10 years old (older mares can be used if proven to be good breeders), in good health, and of good temperament. Recipient mares come in all shapes and sizes, although we typically try to ensure the recipient mare is of a similar height and build to the donor mare. Recipients must have a clean reproductive history and their uterus must be healthy. Recipient mares come from all sources, they can be mares with mild lameness issues or perhaps mares that simply needed a new home. It is also important that recipient mares show no major vices; although the foal has no genetic connection with the recipient mother, the recipient nurtures the foal until weaning so has influence over the foal’s initial learned behavior. These mares can be both maiden and non-maiden and although the birth weights of foals born from maiden recipient mothers can be lower, these foals have generally caught up in size by weaning.
There is a short window of time in which an embryo must be flushed from the donor mare and transferred to the recipient mare. The recipients cycle must closely match the donors. Medication are used to control the recipient and adjust her to match the donor. Typically, 3-5 recipients are synchronized for each donor mare. The recipient mare is carefully chosen to receive the embryo from the donor mare. Each mare that is synchronized is examined in detail to identify her suitability for receiving the donor’s embryo before the mare is chosen. All recipient mares are supplemented with progesterone after receiving a transferred embryo. After a successful transfer, the recipient mare must be closely monitored to ensure that she carries the embryo to full term. Our recipients are checked in foal at 11 days, 14 days, 21 days, 28 days then once per week until leaving the facility. After 30 days and after cleared by the veterinarian, the recipient mare is free to go home. Before the pregnant recipient is allowed to leave the facility, we ask that all outstanding fees and invoices are paid in full.
Owners of valuable mares can now utilize their mares to generate income in much the same way that stallion owners do. Valuable mares can produce embryos multiple times each breeding season. These valuable embryos can be immediately transferred or frozen for future use. All donor mares are kept in private stalls or private paddocks (unless the owner request their personal horses be housed together in a paddock). Individual nutritional modifications and or supplementations are provided for each mare if needed. Various environments are available for your mare(s) depending on her needs. A low stress environment creates better fertility and improved fertility results in pregnancies. Daily turnout is available for the mare(s) if so desired. Regular grooming and bathing is a part of our routine care. It is our goal that your mare is cared for with respect and love during her stay, and that when she is returned to you it is in the best condition possible.