Med. Weter. 71 (4), 195-197, 2015

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Cuervo-Arango J.
Choosing the sex of the offspring in a commercial equine embryo transfer center
It is becoming popular for horse breeders to demand to know in advance the sex of the future offspring of their mares. An example is the Polo Pony breed in Argentina, in which females are preferred over males. The main two techniques available for choosing the sex of the offspring are artificial insemination with sex-sorted semen and pre-implantation genetic diagnosis (PGD). These two techniques, however, are time consuming, expensive, and require specialized equipment and staff. Furthermore, neither technique is 100% accurate. Both of them require a confirmation of the fetal sex by transrectal ultrasonography at day 60 to day 70 of gestation. This consists in identifying the position of the genital tubercle in relation to the umbilical cord and the tail. In females, the genital tubercle is located close to the tail, whereas in males it is close to the umbilical cord, in a more cranial position. The use of this technique has become popular among field veterinarians in some countries for choosing the sex of the offspring in recipient mares after embryo transfer. This procedure involves selective abortion by the intra-uterine administration of PGF in mares carrying a fetus of the non-desired sex Most mares expel the fetus and fetal membranes within 48 h of the treatment. Recipient mares are then used for another embryo transfer, once they resume normal cyclicity.
Key words: sex, offspring, embryo transfer