Estonian scientists are aiding the reproduction of sport horses through assisted reproductive techniques

If all goes according to plan, the first foal in Estonia, conceived with an ovum harvested from one mare, inseminated in the laboratory of Estonian University of Life Sciences using the ICSI technique, and subsequently transferred to another mare, will be born in August next year. Achieving the growth of an embryo through assisted reproduction technology and establishing a viable pregnancy has figuratively elevated horse breeders from Estonia to a membership in an elite club.

To date, only five companies in Europe have provided the service of in vitro fertilization in horses, and now Estonians have joined this exclusive group. A similar service of in vitro production of horse embryos is offered by Ghent University in Belgium, a few private companies, and now this capability is also available at the University of Life Sciences in cooperation with Luunja Stables and Perila Stables, explained the initiative's leader, Elina Tsopp, a junior researcher in breeding and biotechnology at the University.
The mare, impregnated with an ICSI embryo, is located at Luunja Stables. The embryo transfer was carried out by veterinarian Ulrika Tuppits. “Trials were conducted simultaneously in both stables. The fact that pregnancy was first achieved at Luunja Stable was simply a matter of luck."

Our veterinary scientists began the trials already two years ago, and according to Tsopp, the easiest way to explain the procedure is that it is very complicated. But what makes it so intricate? "The ovum needs to be injected with one sperm, that is, a single spermatozoon," explained Tsopp. Considering the size of the cells this in itself is already a delicate procedure. But this still does not guarantee the successful fertilization of the ovum. Everything depends on the quality of the cells collected with the OPU procedure, the transport conditions, the quality of the sperm and several other factors, said Tsopp.

The OPU-ICSI technique is in high demand among horse breeders. “Such biotechnology helps to produce offspring from mares involved in top-level sports without disrupting their athletic careers. Furthermore, the OPU-ICSI technique allows obtaining offspring from mares that otherwise could not produce offspring or to use the sperm of very valuable stallions more efficiently," explained Tsopp. It's no secret that in equestrian circles, in vitro fertilization is a very hot topic. Nowadays, in addition to selling horses and foals, embryos are also being sold.

Sport horses are not impregnated due to their athletic careers, yet all stables aspire to have offspring from the best horses. Now, in addition to the traditional embryo flushing, there is also the possibility of obtaining offspring from the best mares through the OPU-ICSI technique: during a quick procedure, oocytes are retrieved from the ovaries, and the horse can go straight back to sport after a rest day. The embryos are taken to the laboratory for fertilization, and the fertilized cells grow in the incubator for 7-10 days until they are ready for transplantation or freezing.

Another significant reason for using biotechnology is the high cost of semen from top stallions. A sperm straw from some stallions can cost 30,000 euros or even more. Artificial insemination of a mare often requires two or three straws, and a successful pregnancy is not guaranteed. However, by using the ICSI technique, it is possible to fertilize hundreds of eggs in laboratory conditions with a single straw of sperm, providing the best genetic combinations for hundreds of offspring.

Up to 20 eggs can be obtained from one mare at a time using the OPU method, which involves aspirating follicles with a long needle and a vacuum pump. The breeding season for horses falls between spring and fall, but the OPU method allows for the retrieval of eggs throughout the winter as well. The gestation period for a mare lasts 11 months. The first test tube foal in Estonia will be born in August next year.

The breakthrough in biotechnology for horse breeding was supported by the HIVET project funded by Agricultural Registers and Information Board (PRIA), Luunja Stud OÜ, and Cärrot OÜ. The team of veterinarians from the Estonian University of Life Sciences includes Ulrika Tuppits, Ants Kavak, Anni Viljaste-Seera, and Andres Reilent, along with embryologist Elina Tsopp. The project's significant collaborators are Luunja Stable, led by Sven Šois and Urmas Raag, and Perila Stable, led by Kristiina Pähn and Erik Aedviir.