Equine embryo transfer: review of developing potential

Uterine influences on embryogenesis and early placentation in the horse revealed by transfer of day 10 embryos to day 3 recipient mares

“…In the horse, previous studies have shown maximum pregnancy rates to be achieved when the embryos are transferred to the recipients that have ovulated between 1 day before and 3 days after the donor (Allen 1982, Squires et al 1982, Stout 2003, 2006. That pregnancies resulted despite 7 days asynchrony between donor and recipient mares in three instances in the present experiment is quite remarkable in comparison with other species.…”

Negative uterine asynchrony retards early equine conceptus development and upregulation of placental imprinted genes

“…Only grade 1e2 embryos [26] were used for embryo transfer (ET). In order to produce the desired 20 pregnancies, a total of 26 day 8 embryos were transferred, as previously described [25], to recipient mares that had either ovulated on the same day as the donor (synchronous; n ¼ 13), or 5 days after the donor mare (asynchronous; n ¼ 13, Fig. 1).…”

“…On day 8 after ovulation, embryos were recovered from donor mares by uterine lavage, as described previously [25]. Recovered embryos were washed in holding medium (Syngro; Bioniche Animal Health, Pullman, WA, USA) and their diameter was measured using a stereomicroscope (Olympus SZ-ST; Olympus, Tokyo, Japan) equipped with an eye-piece micrometre.…”

Embryo transfer in no cycling Crioula and Quarter horse breeds treated with estradiol cipionate and long-acting progesterone

“…According to Ricketts and Alonso (1991) and Morris and Allen (2002), the age is a very important predisposing factor for the endometrial degeneration, a condition that may compromise the maintenance of the gestation. Furthermore, the recipient's physical condition in regard to the donor and to the stallion (Stout, 2006) should also be considered. There are several reports describing that the discrepancy between the genetic dimension of the embryo and the recipient mare affects the development intrauterine and the post-natal in different aspects.…”

“…Variables such as milk production, maternal skill, age, uterine and vulva condition must be considered for recipient selection (Alonso, 2008). Another important characteristic to be considered is the age of animal (Carnevale et al, 2000;Stout, 2006), considering that the ideal age would be between 3 to 10 years (Squires and Seidel, 1995;Squires et al, 1999). According to Ricketts and Alonso (1991) and Morris and Allen (2002), the age is a very important predisposing factor for the endometrial degeneration, a condition that may compromise the maintenance of the gestation.…”