PROTOCOLOS DE INDU O E SINCRONIZA O DO ESTRO EM OVELHAS

The objective of this study was to evaluate the effects of progestagen treatment of different duration, PGF2a and ram effect on estrus induction synchronization in ewes. In Experiment I, ewes (n=48) received vaginal sponges with MAP (medroxyprogesterone) for nine or 14 days (G-9 and G-14, respectively), followed by PGF2a treatment and estrus detection. There were no differences in estrus (69.6 and 80%), conception (50 and 55%), and pregnancy rates (34.8 e 44.0%) between G-9 and G-14, respectively. In Experiment II, ewes (n=151) were divided into three groups: G-6 received vaginal sponges with MAP for 6 days, followed by PGF2a treatment and estrus detection, G-PGF received only PGF2a treatment, and G-EM were only exposed to males after a period of separation. Estrus rates were greater (p<0.05) in G-6 and G-PGF groups (58 and 39%, respectively) than in G-EM group (11%). In conclusion, it was possible to reduce the duration of progestagen treatment; however, the use of PGF2a during the breeding season transition without progestagen seemed to reduce estrus rates.