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Universidade Federal Rural de Pernambuco (URFPE) 2011

Efeito macho associado a estratégias de manejo sobre o desempenho reprodutivo de ovelhas Santa Inês no semiárido do Estado de Pernambuco

CALDAS, Eduardo Luiz Cavalcanti

Titre : Efeito macho associado a estratégias de manejo sobre o desempenho reprodutivo de ovelhas Santa Inês no semiárido do Estado de Pernambuco

Male effect associated with management strategies on the reproductive performance of Santa Inês ewes in semi-arid region of Pernambuco State

Auteur : CALDAS, Eduardo Luiz Cavalcanti

Université de soutenance : Universidade Federal Rural de Pernambuco (URFPE)

Grade : Doutorado em Ciência Veterinária 2011

Résumé
The aim of this study, divided into two trials, was to evaluate the male effect associated with management strategies on the reproductive performance of Santa Inês ewes raised in a semi-extensive regime. In the first experiment, consisting of three treatments (T1, T2 and T3), was evaluate the effect of the separation distance between male and female, before the breeding season of 45 days, on the reproductive activity of pluriparous ewes (n = 60). They were kept at distances of 3.000 m (T1), 3 m (T2) and 300 m (T3) from the breeders (n = 3) 60 days before of the experiments during both the dry season and the rainy season. In dry season, the first manifestation of estrus averaged at 15.45 ± 10.36 (T1), 9.25 ± 6.41 (T2) and 13.05 ± 10.24 (T3) days. In rainy season, the average was 8.73 ± 5.84 (T1), 9.30 ± 5.62 (T2) and 6.10 ± 5.66 (T3) days. There was no difference in treatment (P > 0.05) during these different climatic conditions. Estrus induction occured in 100% of the females in T1, T2 and T3 in both climatic periods. Estrus synchronization on the first five days of mating season only occured in 20% of the females during dry season, being 30% (T1), 15% (T2) and 15% (T3). In rainy season, synchronisation occured in 40% of females, being 30% (T1), 35% (T2) and 45% (T3), with no differential treatment (P > 0.05) between both climatic periods. The pregnancy percentages in dry and rainy seasons were 85% (T1), 80% (T2) and 75% (T3), with no differential treatment (P > 0.05) between both climatic periods. Prolificacy in dry season was 1.29 (T1), 1.38 (T2) and 1.13 (T3) and in rainy season it was 1.12 (T1), 1.25 (T2) and 1.26 (T3) with no differential treatment (P > 0.05) between rainy and dry seasons. In the second experiment, consisting of three treatments (DT0, DT24, DT48), was evaluate the effect of temporary interrupt of sucking on the reproductive performance of pluriparous ewes (n = 60) with offspring. At DT0 (n = 20), there was no interruption of sucking while at DT24 (n = 20), interrupted of sucking for 24 hours and at DT48 (n = 20), interruption of sucking for 48 hours. Breeders were kept away from the females (n= 60), without visual, odor or hearing contact for 60 days before the breeding season of 45 days during the dry season. Estrous percentages were 90% (DT0), 100% (DT24) and 100% (DT48), with no difference (P > 0.05) among treatments. Estrous synchronization up to the 5th day of mating season was 15% (DT0), 30% (DT24) and 25% (DT48), with no difference among treatments. Pregnancy percentages were 38.4% (DT0), 60.0% (DT24) and 45.0%(DT48) with no difference (P > 0.05) among treatments. Prolificness was 1.43 (DT0), 1.17 (DT24) and 1.22 (DT48), with no difference (P > 0.05) among treatments. The results of the first experiment allow us to conclude that the ram effect can be obtained simply by avoiding physical contact between the breeder and the female as well as that the 45 day mating season can take place in both the rainy and dry season. The data from the second experiment allow us to conclude that temporary weaning is efficient to induce estrous, however is not to synchronize estrous as well as to increase the pregnancy rate and prolificacy of Santa Inês ewes in the breeding season of 45 days during dry period.

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