Effect of timing and induction of estrus and early weaning on the reproductive performance of ewes deslanadas and performance of lambs.

The aim of this study was to evaluate the effects of synchronization/estrus induction and the early weaning in the reproduction performance the hairless ewes and the lambs performance.For this was development two studies. The first tested two treatment of synchronization with the conventional method with 14 days of progestagen application (long-term method=TL) and the short-term with use implants for five days (short-term method= TS) on the estrus incidence, synchronization degree, pregnancy and birth rate of hairless ewes. The second study was the aim evaluate the effect of early weaning (EW), with 45 days of age, in relation to the traditional weaning (WT),with 90 days, on post-weaning performance growth rate of lambs, raised in semi-intensive system. The first study was use 19 hairless ewes, being 9 ewes for TL and 10 ewes for TS. All ewes were synchronized with intravaginal implant impregnated with 60 mg of Medroxiprogesterona Acetate (MAP) inserted in the cranial portion of the vagina and after the sponge removal, was applied equine chorionic gonadotrophin (eCG). Estrus was detected by vasectomized ram every 4 hours, after 24 h of the sponge removal, and those ewes that were detected in estrus were mated with an entire ram, 12 hours after the detection. The pregnancy diagnosis was done by ultrasonografic 45 days after mating. Data were analyzed by the procedure of the Lineal General Model (GLM) of the SAS program, to estimate the percentage of females in estrus, time of interval among end of treatment and beginning of the estrus (FT-IE) and the percentage of pregnancy. The synchronization precision between interval among end of treatment and beginning of the estrus was verificaty using q-quadratic test analysing the percentage of ewes in estrous in terval to 8 h (± 4h the modal in the experimental groups). From the total ewes synchronized, 84,2% showed estrus, with the TL method showing 88,8% and the TS 80,0%, without significant difference between treatments (P>0,05). The ewes of the TS group showed a significant (P 0.05) on post-weaning growth weight. Have significant effect (P0,05). As fêmeas do tratamento curto mostraram um intervalo significativamente maior (P0,05). Foi observado diferença significativa (P0,05). Conclui-se que a impregnação progestágena curta constitui um método eficiente para a sincronização do estro de ovelhas deslanadas e que em sistema semi-intensivo, o desmame de cordeiros aos 45 dias de idade constitui uma alternativa de manejo para melhorar a produção ovina. Palavras-chave: Progestágeno, fertilidade, desenvolvimento corporal, sexos