Walkden-Brown S W, Martin G B, Restall B J
School of Rural Science and Natural Resources, University of New England, Armidale, NSW, Australia.
J Reprod Fertil Suppl. 1999;54:243-57.
The induction of synchronous ovulatory activity in anovulatory sheep and goats after the introduction of males, the 'male effect', has probably been used to advantage since these species were domesticated and the underlying physiological and behavioural mechanisms have been progressively elucidated over the past 50 years. Less well understood is the analogous effect of oestrous females on males. This review examines the nature and importance of these male-female interactions in sheep and goats, and describes the most important internal and external factors influencing the reproductive outcomes of such interactions. It is proposed that the male and female effects are both components of a self-reinforcing cycle of stimulation that, under ideal conditions, culminates in the synchronous very rapid onset (within days) of fertile reproductive activity. However, precisely because of the speed of this response, it is suggested that mechanisms have evolved to limit its efficacy, and thus prevent conception at inappropriate times. The complexity of these factors and the interactions between them are highlighted, and a broad conceptual framework for understanding them is proposed based upon an appreciation of variation in both the responsiveness of the target animal and the quality of the signal from the signalling animal.
自从绵羊和山羊被驯化以来，引入公羊后诱导无排卵的绵羊和山羊出现同步排卵活动，即“公羊效应”，可能已被加以利用，并且在过去50年里，其潜在的生理和行为机制已逐步得到阐明。发情母羊对公羊的类似影响则鲜为人知。本综述探讨了绵羊和山羊中这些雌雄互动的性质和重要性，并描述了影响此类互动生殖结果的最重要的内部和外部因素。有人提出，公羊效应和母羊效应都是自我强化刺激循环的组成部分，在理想条件下，这种循环最终会导致在数天内同步快速开始具有生育能力的生殖活动。然而，正是由于这种反应的速度，有人认为已经进化出了一些机制来限制其效力，从而防止在不适当的时候受孕。这些因素及其相互作用的复杂性得到了强调，并基于对目标动物反应性和信号动物信号质量变化的认识，提出了一个理解它们的广泛概念框架。
