Free Access
Reprod. Nutr. Dev.
Volume 46, Number 4, July-August 2006
Symposium: Influence of nutrition and socio-sexual context on reproduction and survival of the young in goats and sheep
Page(s) 401 - 415
Published online 07 July 2006
Reprod. Nutr. Dev. 46 (2006) 401-415
DOI: 10.1051/rnd:2006021

Role of the olfactory systems and importance of learning in the ewes' response to rams or their odors

Hélène Gelez and Claude Fabre-Nys

Station de Physiologie de la Reproduction et des Comportements, UMR 6175 INRA-CNRS-Université de Tours-Haras Nationaux, 37380 Nouzilly, France

(Published online 7 July 2006)

Abstract - In sheep, exposure of seasonally anestrous females to the male or its fleece results in activation of luteinizing hormone (LH) secretion and synchronized ovulation. The study of the neural pathways involved in this phenomenon, commonly named "male effect", show that the main olfactory system plays a critical role in the detection and the integration of the male odor. The accessory olfactory system participates in the perception of the ram odor but does not seem necessary for the endocrine response. According to the hypothesis that the neuroanatomical differences between the two olfactory systems could be associated with different functional roles, we investigated the importance of sexual experience and learning processes in the male effect. Our results showed that female responses depend on previous sexual experience. We also demonstrated that the LH response to male odor could result from an associative learning process. The aim of the present report was to summarize our current knowledge concerning the "male effect" and in particular to clarify the role of sexual experience and learning in the processes involved in this effect.

Key words: ovine / male effect / LH / olfaction / experience

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© INRA, EDP Sciences 2006