title: A note on the effect of continuous ram presence on estrus onset, estrus duration and ovulation time in estrus synchronized ewes.
abstract: During fall season, 18 multiparous Corriedale ewes were divided into two equal groups for the continuous (CON) and intermittent (INT) presence of a ram. Estrus was synchronized with fluorgestone acetate intravaginal sponges that were left 14 days, plus an injection of 200&mgr;g of a prostaglandin F-2alpha analog at sponge removal. Estrus was detected three times a day (at 6 a.m., 2 p.m. and 10 p.m.) by using rams with harnessess and markers. Ovulation time was determined by laparoscopy, starting 24h after estrus detection. Estrus onset was (mean+/-S.E.M.) 32.9+/-1.6 and 45.3+/-4.4h for the CON and INT groups, respectively (P<0.01). Estrus duration was 31.1+/-0.9 and 30.2+/-1.2h, for the same groups, respectively (P>0.05). Ovulation time and the interval from sponge removal to ovulation (ISRO) for the CON and INT groups was 29.0+/-1.5, 62.0+/-2.0, 26.7+/-1.3 and 72.0+/-4.2h, respectively. Ovulation time was not different (P>0.05), but ISRO was shown to be different between treatments (P<0.05). It is concluded that the continuous presence of a ram after sponge removal hastens estrus onset and reduces the interval between sponge removal and ovulation, without modifying estrus duration and time between estrus onset and ovulation.
authors.affiliation: Large Animal Medicine & Surgery, College of Veterinary Medicine, Texas A&M University, 77843-4475, College Station, TX, USA
authors.forename: J E.
authors.initials: JE
authors.lastname: Romano
authors.forename: D
authors.initials: D
authors.lastname: Fernandez Abella
authors.forename: N
authors.initials: N
authors.lastname: Villegas