Male effect associated with suckling interruption on the reproductive performance of Santa Inês ewes / Efeito macho associado ao desmame temporário no desempenho reprodutivo de ovelhas Santa Inês

This study aimed to evaluate the effect of temporary suckling interruption associated with the male effect on reproductive performance of pluriparous Santa Inês ewes. The females were kept apart from the males for 60 days and then randomly distributed into three treatments associated with the male effect (DT0, DT24 and DT48); in DT0, there was no suckling interruption; in DT24, suckling was interrupted for 24 hours, and in DT48, sucking was interrupted for 48 hours. Estrous distribution was observed within 31 (DT0), 27 (DT24) and 38 (DT48) days of the breeding season. Estrous synchronization up to the 5th day of the mating season was observed in 15% (DT0), 30% (DT24) and 25% (DT48) of the females, with no difference among treatments. Estrous percentages were 90% (DT0), 100% (DT24) and 100% (DT48), with no difference among treatments. Pregnancy rates were 38.4% (DT0), 60.0% (DT24) and 45.0% (DT48) with no difference among treatments. Prolificacy was 1.43 (DT0), 1.17 (DT24) and 1.22 (DT48) and did not differ between treatments. In conclusion, temporary suckling interruption associated with the male effect is efficient to induce estrous but not to synchronize estrous or increase the pregnancy rates and prolificacy of Santa Inês ewes during a 45-day breeding season...

O estudo teve como objetivo avaliar o efeito do desmame temporário associado ao efeito macho sobre o desempenho reprodutivo de ovinos Santa Inês. As fêmeas foram mantidas distantes dos machos por 60 dias e aleatoriamente distribuídas em três tratamentos associados ao efeito macho (DT0, DT24 e DT48), no qual em DT0, não houve interrupção da amamentação; em DT24, amamentação interrompida por 24 horas e em DT48, interrupção da amamentação por 48 horas. Distribuição de estro foi observada em 31 (DT0), 27 (DT24) e 38 (DT48) dias da estação de monta. Sincronização de estro até o quinto dia da estação de monta foi observada em 15% (DT0), 30% (DT24) e 25% (DT48) das fêmeas, não havendo diferença entre os tratamentos. Percentagens de estro foram de 90% (DT0), 100% (DT24) e 100% (DT48), não havendo diferença entre os tratamentos. As taxas de prenhez foram de 38,4% (DT0), 60,0% (DT24) e 45,0% (DT48), sem diferença entre os tratamentos. A prolificidade foi de 1,43 (DT0), 1,17 (DT24) e 1,22 (DT48), e não diferiu entre os tratamentos. Em conclusão, o desmame temporário associado ao efeito macho é eficiente na indução do estro, embora não seja eficiente na sincronização de estros e não aumente as taxas de gestação e prolificidade das ovelhas Santa Inês durante uma estação de monta de 45 dias...

Male effect associated with suckling interruption on the reproductive performance of Santa Inês ewes / Efeito macho associado ao desmame temporário no desempenho reprodutivo de ovelhas Santa Inês

This study aimed to evaluate the effect of temporary suckling interruption associated with the male effect on reproductive performance of pluriparous Santa Inês ewes. The females were kept apart from the males for 60 days and then randomly distributed into three treatments associated with the male effect (DT0, DT24 and DT48); in DT0, there was no suckling interruption; in DT24, suckling was interrupted for 24 hours, and in DT48, sucking was interrupted for 48 hours. Estrous distribution was observed within 31 (DT0), 27 (DT24) and 38 (DT48) days of the breeding season. Estrous synchronization up to the 5th day of the mating season was observed in 15% (DT0), 30% (DT24) and 25% (DT48) of the females, with no difference among treatments. Estrous percentages were 90% (DT0), 100% (DT24) and 100% (DT48), with no difference among treatments. Pregnancy rates were 38.4% (DT0), 60.0% (DT24) and 45.0% (DT48) with no difference among treatments. Prolificacy was 1.43 (DT0), 1.17 (DT24) and 1.22 (DT48) and did not differ between treatments. In conclusion, temporary suckling interruption associated with the male effect is efficient to induce estrous but not to synchronize estrous or increase the pregnancy rates and prolificacy of Santa Inês ewes during a 45-day breeding season...(AU)

O estudo teve como objetivo avaliar o efeito do desmame temporário associado ao efeito macho sobre o desempenho reprodutivo de ovinos Santa Inês. As fêmeas foram mantidas distantes dos machos por 60 dias e aleatoriamente distribuídas em três tratamentos associados ao efeito macho (DT0, DT24 e DT48), no qual em DT0, não houve interrupção da amamentação; em DT24, amamentação interrompida por 24 horas e em DT48, interrupção da amamentação por 48 horas. Distribuição de estro foi observada em 31 (DT0), 27 (DT24) e 38 (DT48) dias da estação de monta. Sincronização de estro até o quinto dia da estação de monta foi observada em 15% (DT0), 30% (DT24) e 25% (DT48) das fêmeas, não havendo diferença entre os tratamentos. Percentagens de estro foram de 90% (DT0), 100% (DT24) e 100% (DT48), não havendo diferença entre os tratamentos. As taxas de prenhez foram de 38,4% (DT0), 60,0% (DT24) e 45,0% (DT48), sem diferença entre os tratamentos. A prolificidade foi de 1,43 (DT0), 1,17 (DT24) e 1,22 (DT48), e não diferiu entre os tratamentos. Em conclusão, o desmame temporário associado ao efeito macho é eficiente na indução do estro, embora não seja eficiente na sincronização de estros e não aumente as taxas de gestação e prolificidade das ovelhas Santa Inês durante uma estação de monta de 45 dias...(AU)

Effects of retinoids on the in vitro development of Capra hircus embryos to blastocysts in two different culture systems.

The objective of this study was to evaluate the effect of retinol (RT) and retinoic acid (RA) on the in vitro development of pre-implantation goat embryos cultured in potassium simplex optimized medium or synthetic oviduct fluid or cocultured in oviductal cells monolayer either in potassium simplex optimized medium or synthetic oviduct fluid. A total of 2407 cumulus-oocyte complexes were aspirated from 2 to 6 mm ovarian follicles from slaughtered animals. Selected cumulus-oocyte complexes were subjected to in vitro maturation in TCM 199 for 24 h at 39 °C in an atmosphere of 5% (v/v) CO(2) in humidified air. In vitro fertilization was performed in modified defined medium. Eighteen hours after in vitro fertilization, cumulus cells were removed and presumptive zygotes were randomly distributed into experimental groups. In Experiment 1, presumptive zygotes were cultured in potassium simplex optimized medium, potassium simplex optimized medium + RT, potassium simplex optimized medium + retinoic acid, synthetic oviduct fluid, synthetic oviduct fluid + RT and synthetic oviduct fluid + RA at 39 °C in a humidified atmosphere of 5% (v/v) CO(2), 5% (v/v) O(2) and 90% (v/v) N(2). In Experiment 2, presumptive zygotes were cocultured in potassium simplex optimized medium + oviductal cells monolayer, potassium simplex optimized medium + RT + oviductal cells monolayer, potassium simplex optimized medium + RA + oviductal cells monolayer, synthetic oviduct fluid + oviductal cells monolayer, synthetic oviduct fluid + RT + oviductal cells monolayer and synthetic oviduct fluid + RA + oviductal cells monolayer in an atmosphere of 5% (v/v) CO(2) in humidified air. In both experiments, media were partially changed on day 2 after in vitro fertilization and unfertilized oocytes were excluded from the experiment. Embryos were cultured or cocultured for 8 days. In Experiment 1, there was no effect of RT or RA supplementation on the proportion of oocytes that reached the morula or blastocyst stages. By contrast, Experiment 2 demonstrated that the addition of 0.28 µg/ml RT and 0.5 µm RA to the embryo culture media stimulated (p < 0.05) development to the morula and blastocyst stages under the coculture conditions tested. In conclusion, retinoids play an important role in pre-implantation development of goat embryos and can be used to enhance in vitro embryo production.