Sexual pheromones in the domestic sheep: importance and limits in the regulation of reproductive physiology.

In mammals, primer pheromones are considered as the most important signals involved in socio-sexual stimulation of the reproductive processes. In the domestic sheep, male-female interactions induce changes in the pulsatile rhythm of the LH secretion in both sexes which influences reproductive endocrinology. In the female, the odor of the ram's fleece induces LH secretion and ovulation. The acid sub fraction of the methylene chloride extract under C16 and diols appear to contain the active components. An interspecific action has been observed, as male goat's hair extract is similarly active. In the male, although the receptive female is the most effective to stimulate LH release, no pheromonal action has been demonstrated. In the female, lesions of the vomeronasal system do not eliminate the endocrine response to pheromonal stimulation. Furthermore, in both sexes, anosmia does not impair the response to direct interaction with the sexual partner. In domestic sheep, the existence of primer pheromones has been demonstrated, but other sensory cues could replace olfaction during socio-sexual interactions interfering with the control of reproductive endocrinology.