title: Success rates when attempting to nonsurgically collect equine embryos at 144, 156 or 168 hours after ovulation.
abstract: The purpose of this study was to evaluate the exact age when the equine embryo reaches the uterus. The time of ovulation was determined by hourly ultrasound examinations starting 32 h after an injection of crude equine pituitary gonadotrophin or human chorionic gonadotrophin, or after the first of 4 injections of buserelin. Nonsurgical uterine flushings were carried out 144 h (Day 6), 156 h (Day 6.5) or 168 h (Day 7) after ovulation. Induction of ovulation was attempted in 101 oestrous cycles and 61 of 101 mares (60.4%) ovulated 32-44 h post injection. Sixty embryo collections were performed which yielded: 0/20 embryos at 144 h, 9/17 embryos (53%) at 156 h and 12/23 embryos (52%) at 168 h. The mean (+/- s.e.m.) diameter of the embryo was significantly greater (P<0.01) at Day 7 (244 +/- 15 microm) than at Day 6.5 (186 +/- 9.1 microm), and variability in size was observed among embryos collected from the same mare after synchronous natural multiple ovulations. These results suggest that; i) horse embryos enter the uterus between 144 and 156 h after ovulation, and ii) the time interval between ovulation and fertilisation in mares is inconsistent and/or embryonic development rate may differ between individual embryos.
authors.affiliation: Laboratoire de Pathologie de la Reproduction, The Veterinary School, Nantes, France.
authors.forename: I
authors.initials: I
authors.lastname: Battut
authors.forename: S
authors.initials: S
authors.lastname: Colchen
authors.forename: F
authors.initials: F
authors.lastname: Fieni
authors.forename: D
authors.initials: D
authors.lastname: Tainturier
authors.forename: J F
authors.initials: JF
authors.lastname: Bruyas
mesh_terms: D000818:Animals; D010064:Embryo Implantation / Q000502:physiology*; D004624:Embryo Transfer / Q000379:methods / Q000662:veterinary*; D004622:Embryo, Mammalian / Q000033:anatomy & histology; D005260:Female; D006736:Horses / Q000196:embryology* / Q000502:physiology; D008297:Male; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary; D013997:Time Factors