The objective of this study was to test the efficiency of two protocols in synchronize the ovulation of sows in early weaning system. Thirty multiparous crossbred (Large-White x Landrace) sows with a mean± SD of 4.4± 2.0 parturitions and 14.8± 0.7 days in lactation were divided into three groups of 10 animals each: group 1- control; group 2- received 1000 IU of PMSG (FOLLIGON® , INTERVET) IM, 48 hours after weaning + 0.25mg of GnRH (FERTAGIL® , INTERVET) IM, 72h after PMSG; group 3- received 1000 IU of PMSG 48 hours after weaning + 500 IU of hCG (PROFASI® , SERONO) IM, 72h after PMSG. Time of ovulation was monitored by transrectal ultrasound. Synchronization of ovulation rates (ovulated within 48 hours after the treatment with hCG or GnRH) in groups 2 and 3 were higher (94.7%; P< 0.01) than in group 1 (40%). Sows from groups 2 and 3 showed a tendency of higher pregnancy rate than those from group 1 (95% vs. 70%; P<0.10), but similar weaning-to-estrus interval (96.5± 3.0h vs. 130.2± 31.4h) and similar litter size (10.9± 0.8 vs. 12.0± 0.9), respectively. The data show that the protocols used in the current study were efficient in synchronize time of ovulation and render possible the use of AI at a predetermined moment.
Sow; synchronization of ovulation; early weaning; hormone
