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O Instituto de Investigação e Tecnologia da Agronomia e Meio Ambiente (IITAA) desenvolve trabalho de investigação com o objetivo de perseguir estudos em diversas áreas, como a caracterização / previsão do clima insular e os efeitos das mudanças globais em comunidades do oceano para os to... Ler mais »

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The effect of exposure to oestrous ewes on rams' sexual behaviour, plasma testosterone concentration and ability to stimulate ovulation in seasonally anoestrous ewes

Agricultura e Produção Animal

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Referência

Rosa, H. J. D., Juniper, D. and Bryant, M. J. (2000). The effect of exposure to oestrous ewes on rams' sexual behaviour, plasma testosterone concentration and ability to stimulate ovulation in seasonally anoestrous ewes. Applied Animal Behaviour Science, 67 (4): 293-305.

Resumo

Abstract Previous research has shown that the proportion of seasonal anoestrous ewes that ovulate in response to the introduction of rams (‘ram effect’) is dependent upon pheromonal and sexual behavioural stimuli emitted by the rams. Since the close contact with oestrous ewes is likelly to increase the rams' libido and level of testosterone secretion, which in turn has been suggested to positively influence the production of pheromones, it could probably be used to improve the efficacy of the ‘ram effect’. In the present experiment 272 ewes were introduced to rams without recent experience of oestrous ewes, to rams recently exposed to oestrous ewes, to oestrous ewes and rams with or without recent experience with oestrous ewes, or remained isolated. Exposure to oestrous ewes increased (P<0.05) the libido of rams and the previous contact with oestrous ewes resulted in more time (P<0.05) spent by rams in close proximity (within 5 meters) to anoestrous ewes. However, there was no statistical evidence that increased sexual activity resulted in an improvement in the ability of rams to stimulate the ovulation in anoestrous ewes. Serum testosterone concentration of rams was elevated equally (P<0.05) when oestrous or nonoestrous ewes were introduced. These results sugest that a limit exists in the ability of a flock of seasonal anoestrous ewes to respond in ovulatory terms to increasing intensity of stimulation. Key words: Sheep; Ram effect; Testosterone; Sexual behaviour

Domingo, 31 Dezembro, 2000

Equipa

Henrique José Duarte Rosa
Membro Integrado com contrato

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