Exogenous hormone regimens to utilize successfully mares in dioestrus (days 2-14 after ovulation) as embryo transfer recipients.
Two hormone regimens were utilized for recipient mares which were 2-14 days after ovulation at the time of non-surgical embryo transfer. In Exp. I, 20 embryos were transferred non-surgically into recipient mares which had been given 22 mg altrenogest daily starting the day of recipient ovulation. Higher (P less than 0.05) pregnancy rates (50% vs 0%) were obtained in mares which were 2-6 days after ovulation at the time of transfer compared with mares which were 7-12 days after ovulation. In Exp. II, on the day the donor mare ovulated (Day 0), 10 mg PGF-2 alpha were given to the recipient mare at 0 h, 20 mg oestradiol cypionate at 12, 24 and 36 h, 500 mg progesterone in oil at 48 h and then 22 mg altrenogest at 60, 72 and 96 h. Altrenogest (22 mg/day) was continued until Day 28 (fetal heart beat). The pregnancy rate (58% vs 10%) was higher (P less than 0.05) for the 12 recipient mares which were 10-14 days after ovulation than for the 10 mares that were 5-8 days after ovulation when treatment began. Early embryonic loss was detected in 4/8 pregnant recipient mares between Days 21 and 28 of gestation. We suggest that mares which are 2-14 days after ovulation and not in ovulation synchrony with the donor may be used as embryo transfer recipients; mares which are in early dioestrus can be given altrenogest while those in mid- to late dioestrus can be placed on the more complex hormone regimen.
Pool, K. F., J. M. Wilson, G. W. Webb, D. C. Kraemer, G. D. Potter, and J. W. Evans. "Exogenous Hormone Regimens to Utilize Successfully Mares in Dioestrus (Days 2-14 After Ovulation) as Embryo Transfer Recipients." Journal of reproduction and fertility. Supplement 35 (1987): 429-432.
Journal of reproduction and fertility. Supplement