Over the past ten years Dr Karin Hendriks, European specialist in equine reproduction, has seen that Embryo Transfer (ET) has become a lot more common. During the previous year all the Covid 19-related issues have contributed to this increase: because competitions were cancelled sport mares were used for ET, which allows them to get back into the sport as soon as competitions can go ahead again.
In short, embryo transfer entails flushing of a young embryo from the donor mare, which is subsequently transferred to a recipient mare. This recipient mare will then carry the pregnancy to full term and nurse the foal. There are several reasons to opt for this construction. Prioritising the mare’s sport career can be a reason, another is speeding up genetic evolution. Because after all, genetically valuable mares can produce multiple offspring in just one year. Techniques have improved and more and more knowhow has become available.
Ability to cope with disappointments
Karin Hendriks gave a few practical tips owners have to take into account when considering ET for his/her mare. Are you planning to use your own surrogate mare or rent one? Hendriks advised to get in touch with the stallion keeper to discuss practical issues in advance, such as the availability of semen from the stallion of your choice. She always tells owners to be prepared for disappointments. For one live foal the average number of flushings is three.
Once donor mare and recipient mare have both received a clean bill for health and fertility, the process can be initiated. It is essential that the cycles of donor mare and recipient mare (practically) correspond. By way of hormonal intervention, for example by using injections to bring on the heat, the cycles of donor mare and recipient mare can be synchronised. After flushing of the embryo from the donor mare it has to be transferred to the recipient mare within 24 hours.
A number of factors are of influence for the success rate of ET. Important factor is to make sure the mares suffer as little stress as possible from the entire process, other factors are the mare’s age and the use of fresh/cooled semen. Costs for ET range somewhere between three- to five thousand Euros, depending on the availability of your own surrogate mare or having to rent one. But, as Karin Hendriks pointed out, foals born via ET usually generate more money because they are genetically valuable.
Dr Karin Hendriks graduated at the Veterinary Faculty of Utrecht in 2001. She has researched equine reproductive techniques and in 2018 took her Ph D based on this subject. Hendriks is a Certified Equine Veterinarian as well as a European Specialist Equine Reproduction and works as Clinical Director Horses at ‘De Graafschap Dierenartsen’ in Vorden. She is the owner of Hendriks EQ Repro Consultancy and part-owner of Seldsum EQ Hendriks, which specialises in the latest modern reproduction techniques.