Embryo Transfer Tips and Trics

Introduction

In recent years, the use of embryo transfer has significantly increased in the northern part of Europe. Several veterinary practices in The Netherlands, Belgium, Germany and France have integrated this technique in their reproductive services. The main reasons for this new development are a better understanding of the techniques of embryo transfer and transportation of cooled embryos as well as the availability of large, centralized recipient herds for the transplantation of transported, cooled embryos. It is especially the development of a practical method of short-term (24 hr) storage and transportation of equine embryos and the development of practical storage media that has allowed a breakthrough of this technique in Europe. This allows embryos to be collected in the “field” and then shipped to a centralized facility for transfer to suitable recipient mares. The ability to transport cooled embryos provides veterinarians with the opportunity to offer embryo transfer service without the onerous task of maintaining recipient mares, and eliminated the need to ship donor mares to a centralized facility. This article will review current equine embryo transfer techniques.

ET applications

The applications of embryo transfer include: 1) obtaining foals from (young) performance mares that continue to compete or that are for sale, 2) obtaining multiple foals from individual mares each year, 3) obtaining foals from two-year-old mares, 4) obtaining foals from reproductively unsound mares, and 5) obtaining foals from mares with non-reproductive health problems. Although embryo transfer was initially proposed as a promising method for obtaining foals from aged, subfertile mares, experiments utilizing oocyte transfer and embryo transfer have documented that many oocytes/embryos produced by aged, subfertile mares are inherently defective and have low survival rates after transfer to recipient mares; therefore, aged, subfertile mares are not optimal candidates for embryo transfer. Especially veterinary practices that start to offer this technique should carefully select fertile donor mares in order to give their ET program the best chances for success.

ET timing

Embryo collection is typically done on Day 7 or 8 after ovulation (Day 0 = day of detection of ovulation). Since the [...]