title: Effect of progesterone impregnated vaginal sponges and PMSG administration on estrus synchronization in mares.
abstract: Estrus synchronization trials with mares were carried out using progesterone impregnated vaginal sponges and pregnant mare serum gonadotropin (PMSG) injections. In Phase 1, 10 non-pregnant, non-lactating mares were administered 1 g progesterone via vaginal sponges (5 x 6 cm) without regard to stage of estrous cycle. Sponges were replaced on day 7 of trial for an additional seven days. On day 12, PMSG (1000 IU, IM) was administered to five mares (Group A); five control mares (Group B) received no injections. There was no difference (P>.05) in estrus synchronization between Group A and Group B. Total sponge retention was 75%. In Phase 2, 11 non-pregnant, non-lactating mares were administered 2 g progesterone via vaginal sponges (10 x 6 cm) without regard to stage of estrous cycle. Sponges were replaced on day 7 of trial for an additional seven days. Estrus behavior was exhibited in 54.5% of mares by day 19. Total sponge retention was 95.4%. There was no difference (P>.05) in estrus synchronization or sponge retention between Phase 1 and Phase 2. The larger Phase 2 sponges showed less (P<.01) posterior movement within the vagina than the smaller Phase 1 sponges.
authors.affiliation: Department of Animal Industries University of Connecticut Storrs, Connecticut 06268 USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Dinger
authors.forename: E E
authors.initials: EE
authors.lastname: Noiles
authors.forename: M J
authors.initials: MJ
authors.lastname: Bates