Following research to better understand embryonic development of foals, researchers have announced that four foals were successfully born as the result of the transfer of genotyped and cryopreserved embryos.
Researh leading to healthier foals
Genotyping allows scientists to choose the embryos they want to use based on different criteria: sex, as in this experiment, the absence of known genetic disorders, or, perhaps in the future other traits that are tied to behavior.
The research was undertaken not only to better understand embryonic development, but also to control livestock reproduction, and maintain breed genetic diversity. The research also furthers the advantage of the horse industry to determine the traits of a future foal.
Genotyping allows scientists to choose the embryos they want to use based on different criteria: sex, as in this experiment, the absence of known genetic disorders, or, perhaps in the future other traits that are tied to behavior, such as emotivity or sociability.
The INRA Val de Loire center at Nouzilly is where the technology to maintain embryo viability following genotyping and cryopreservation was honed, and then, last summer, the transfer of several embryos took place at the IFCE Haras du Pin Stud Farm, located in the French department of Orne. The partnership between the two institutions has now been cemented by the birth of the healthy foals.
Although embryo preservation techniques are already well developed for bovines, small ruminant species, and even humans, preserving horse embryos is a very complex process. For instance, horse embryos vary greatly in size: 7-day-old embryos range in diameter from 200 to 700 micrometers.
It is very difficult to cryopreserve the largest embryos because the liquid inside them forms ice crystals when the embryos are frozen at very cold temperatures. What's more, horse embryos are surrounded by a capsule that interferes with successful cryopreservation.
The factor that currently limits the use of embryo transfer is its cost: the transfer center has to maintain a team of recipient mares that are reproductively synchronized with the donor mares.
Cryopreservation means that the transfer doesn't have to take place immediately; it can wait until a recipient mare becomes available to receive the embryo. Finally, it may now be possible to directly repopulate horse herds that have experienced losses as a result of various issues, such as disease-related problems, instead of having to use the indirect technique of crossbreeding.
For researchers, their next goal is to simplify the process -- to make this technology more accessible and user friendly for those in the horse industry.