[Effect of the male presence on the reproductive mechanisms in female mammals].

In various physiological situations, the presence of the male may interfere with the timing of the physiological events of female reproduction. Contact with the male hastens puberty in a variety of species, provided that the female has reached a given age and weight. The male presence may induce synchronized oestrus in the adult female. In the case of seasonal or lactation anoestrus in ewes, contact with the ram increases the pulsatile release of LH within a few minutes, resulting in a preovulatory surge 24 hrs later, followed by ovulation, but usually no behavioural oestrus. However, the development of the corpus luteum is abnormal in half of the cases, leading to an abnormally short 7-day oestrous cycle. During oestrus itself, the male presence reduces markedly the duration of sexual receptivity and hastens ovulation. Direct contact is not needed to produce these effects which can be mediated by the sense of smell and also by other senses, acting in a cumulative, and possible substitutive, way. Male-induced ovulation would ensure a higher probability of fertilization in species in which the males and females are not permanently associated. Furthermore, the resulting synchronized reproduction might have an adaptative value by reducing predation at birth in wild species. Such effects could also be used for the control of domestic animal production.