Efficiency of superovulation and in vivo embryo production in eFSH-treated donor mares after estrus synchronization with progesterone and estradiol-17beta.
Reliable methods of regulating estrus and stimulating superovulations in equine embryo transfer programs are desirable. Our objectives were to investigate the efficacy of a progesterone and estradiol-17beta (P&E) estrus synchronization regimen in mares with and without subsequent equine follicle-stimulating hormone (eFSH) treatment and to examine the effects of eFSH on folliculogenesis and embryo production. Cycling mares were treated with P&E daily for 10 d. On the final P&E treatment day, prostaglandin F(2alpha) was administered, and mares were randomly assigned to one of two treatment groups (n=20 mares/group). In both groups, mares were examined daily by transrectal ultrasonography. In the eFSH group, twice-daily eFSH treatments were initiated at follicle diameter 20 to 25 mm and ceased at follicle > or =35 mm; human chorionic gonadotrophin (hCG) was administered after 36 h. In the control group, eFSH treatments were not given, but hCG was administered at follicle > or =35 mm. Mares were inseminated with fresh semen, and embryo recovery attempts were performed 8 d postovulation. Synchrony of ovulations within each group appeared to be similar. Six mares in the eFSH group failed to ovulate. The eFSH treatment resulted in higher (P<0.05) numbers of preovulatory follicles and ovulations; however, embryo recovery rate did not increase (eFSH 1.0+/-0.4 vs. control 0.95+/-0.1 embryos/recovery attempt), and embryo per ovulation rate was significantly lower (36% vs. 73%). The eFSH-treated mares had significantly higher frequency of nonovulatory follicles (28% vs. 0) and higher periovulatory serum concentrations of estradiol-17beta. Based on our findings, combined P&E and eFSH regimens cannot be recommended for cycling donor mares.
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Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. tal.raz@usask.ca
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D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D004624:Embryo Transfer / Q000379:methods / Q000662:veterinary; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage*; D006736:Horses / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary*; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000502:physiology; D010060:Ovulation; D011374:Progesterone / Q000008:administration & dosage / Q000097:blood; D013480:Superovulation; D020858:Tissue and Organ Harvesting / Q000379:methods / Q000662:veterinary; D014463:Ultrasonography
D006063:Chorionic Gonadotropin; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone