Vitrification or freezing of embryos is a relatively new technique that is an excellent way to preserve genetics. In this process suitable embryos that are recovered are processed, frozen and stored in liquid nitrogen indefinitely. They can then be thawed and transferred into a recipient mare when it is convenient. Advantages include:
- Storage of genetics in the event of loss of the mare;
- Embryos can be collected at the end of the show season and transferred at a preferred date;
- Late foaling mares can store embryos for transfer early in the following season.
Pregnancy rates following transfer of frozen-thawed embryos are slightly lower than fresh or chilled embryos. Careful consideration should be made prior to deciding to freeze embryos versus using them fresh as there will be a lower pregnancy with each manipulation of the embryo.