Male effect associated with suckling interruption on the reproductive performance of Santa Inês ewes

Abstract

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.Keywords: anestrous, biostimulation, reproduction, sheep. EFEITO MACHO ASSOCIADO AO DESMAME TEMPORÁRIO NO DESEMPENHO REPRODUTIVO DE OVELHAS SANTA INÊSRESUMO: 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.Palavras-chave: anestro, bioestimulação, ovinos, reprodução.

Progesterone (P4), luteinizing hormone (LH) levels and ovarian activity in postpartum Santa Inês ewes subject to a male effect

“…Postpartum ewes of 2 to 3 years of age were initially evaluated for body condition score and were preselected if they displayed a score of 2 or 3, as described by Caldas et al (2015a, b). The anestrus condition was evaluated by reproductive tract ultrasonography following Santos et al (2004).…”

“…Selected ewes were identified with numbered plastic ear tags and colored neckband in order to ease management. Male effect preconditioning was established by isolating ewes from rams for 30 days at a distance of 10 m, which avoids physical contact between genders as previously described by Caldas et al (2015b). Santa Inês rams (n = 2) were preselected according to fertility records and were subject to an andrology exam a week before the onset of the experiment.…”

“…Sheep production can be improved by genetic selection for ewes of improved reproductive efficiency, with lower age at first lambing, shorter time between deliveries and increased prolificacy (Notter and Copenhaver, 1980;Azzarini, 2004). The male effect alone (Sasa et al, 2011;Caldas et al 2015a, b) or combined with pharmaceuticals (Knights et al, 2001;Ungerfeld et al, 2004;Monreal et al, 2009;FerreiraSilva et al, 2017) is a simple, effective and low-cost approach to reducing the duration of postpartum anestrus without affecting pregnancy rates (Caldas et al, 2015a, b).…”

“…The male effect alone (Sasa et al, 2011;Caldas et al 2015a, b) or combined with pharmaceuticals (Knights et al, 2001;Ungerfeld et al, 2004;Monreal et al, 2009;FerreiraSilva et al, 2017) is a simple, effective and low-cost approach to reducing the duration of postpartum anestrus without affecting pregnancy rates (Caldas et al, 2015a, b).…”

“…This variation in LH pulses may be due to silent estrus behavior in ewes under anestrus (Knight et al, 1983;Thimonier, 2000). Thus, depending upon the resulting type of corpus luteum that is formed, females may have displayed short or normal estrous cycles (Caldas et al, 2015a, b), accompanied by an increase in P4 concentration (Sasa et al, 2011).…”