title: Folliculogenesis, embryo parameters and post-transfer recipient pregnancy rate following equine follicle-stimulating hormone (eFSH) treatment in cycling donor mares.
abstract: BACKGROUND
  Induction of multiple ovulations, or superovulation, may potentially increase the efficiency of equine embryo transfer programs. Our objective was to investigate the effects of equine follicle-stimulating hormone (eFSH) treatment on the success rate of embryo transfer programs in mares.
  
  
  METHODS
  In the research facility of the University of Saskatchewan, Canada, we studied 12 donor mares and 37 recipient mares during the physiological breeding season. Donor mares were used in two consecutive oestrous cycles: the first served as the control cycle and in the second an eFSH regimen was applied (eFSH cycle). In the control cycle, mares were administered human chorionic gonadotropin (hCG) to induce ovulation when a follicle ≥35 mm in diameter was detected by transrectal ultrasonographic examination. In the second oestrous cycle, twice-daily eFSH treatment was initiated when a follicle ≥25 mm was detected and treatment ceased when a follicle ≥35 mm was present, at which time hCG was administered. All donor mares were artificially inseminated while in oestrus using fresh semen collected from a stallion of proven fertility. At 8 days post-ovulation, embryos were recovered transcervically and transferred individually to the uterus of a synchronised recipient mare.
  
  
  RESULTS
  The eFSH treatment stimulated the ovary and resulted in greater numbers of ovulations and recovered embryos; however the recovered embryos tended to have a lower morphological grade than the control embryos, and the recipient pregnancy rate per transferred embryo was lower than anticipated.
  
  
  CONCLUSIONS
  The numbers of recipient pregnancies and foals born that resulted from eFSH treatment were not different from the control.
authors.affiliation: Department of Large Animal Medicine and Surgery, Veterinary Teaching Hospital, Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel. talrazg@gmail.com
authors.forename: T
authors.initials: T
authors.lastname: Raz
authors.forename: G M
authors.initials: GM
authors.lastname: Green
authors.forename: S D
authors.initials: SD
authors.lastname: Carley
authors.forename: C E
authors.initials: CE
authors.lastname: Card
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D004624:Embryo Transfer / Q000379:methods / Q000662:veterinary*; D004973:Estrus Synchronization; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage*; D006736:Horses / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D018873:Pregnancy Rate; D013480:Superovulation
chemical_list: D006063:Chorionic Gonadotropin; D005640:Follicle Stimulating Hormone