Dwyer C M
Sustainable Livestock Systems Group, SAC, Edinburgh, EH9 3JG, UK.
J Anim Sci. 2008 Apr;86(14 Suppl):E246-58. doi: 10.2527/jas.2007-0404. Epub 2007 Aug 20.
The relatively intensive supervision afforded many ewes at lambing time is a barrier to the development of low-input sheep management systems. However, in some flocks, reduction in this level of supervision may initially affect lamb mortality and animal welfare. In this review, possibilities for optimizing behavioral interaction between the ewe and lamb are considered, with the goal of improving lamb survival without the need for high levels of human supervision. At birth, ewes show specific behavioral patterns (e.g., licking or grooming, low-pitched bleats, udder acceptance) that facilitate the transition of the lamb from pre- to postnatal life and that accompany the formation of an exclusive olfactory memory for the lamb. The lamb also performs a specific sequence of behaviors directed toward standing, finding the udder, and sucking. The successful accomplishment of these behavior patterns is vital for the formation of a strong attachment between both partners, and for lamb survival. The expression of maternal behavior in the ewe is affected by her previous maternal experience, by nutrition in pregnancy, by breed, by temperament, and, to some extent, by the behavior of her lamb. The maternal care expressed by a ewe at parturition is indicative of her behavior throughout that lactation and in successive pregnancies, suggesting an underlying basis to maternal care intrinsic to that ewe. Studies with Scottish Blackface and Suffolk ewes show that ewes expressing high levels of maternal care have elevated plasma estradiol in late gestation compared with ewes with poorer maternal care, and that circulating estradiol concentration is correlated with maternal behaviors. Although the genetic basis of maternal behaviors has still to be fully determined, there are possibilities of improving maternal behavior by selection, and a better understanding of the neuroendocrine processes underlying individual differences in maternal behavior may help in developing selection strategies. In addition, selection on lamb behaviors, which show some genetic basis, may also be a route to improve lamb survival. Because behavior of both the ewe and lamb is affected by environmental factors, appropriate management, through pregnancy and at parturition, will enhance the expression of maternal behavior and lamb vigor, and so contribute to improving lamb survival.
在产羔时对许多母羊进行相对密集的监管是低投入养羊管理系统发展的一个障碍。然而，在一些羊群中，降低这种监管水平最初可能会影响羔羊死亡率和动物福利。在本综述中，我们考虑了优化母羊与羔羊之间行为互动的可能性，目标是在无需高水平人工监管的情况下提高羔羊存活率。出生时，母羊会表现出特定的行为模式（如舔舐或梳理、低声咩叫、接受乳房），这些行为有助于羔羊从出生前到出生后的过渡，并伴随着对羔羊形成独特的嗅觉记忆。羔羊也会执行一系列特定的行为，包括站立、找到乳房和吸吮。这些行为模式的成功完成对于双方建立牢固的依恋关系以及羔羊的存活至关重要。母羊的母性行为表达受到其先前的育幼经验、孕期营养、品种、性情的影响，在一定程度上也受到其羔羊行为的影响。母羊在分娩时表现出的母性关怀表明了她在整个哺乳期和后续妊娠中的行为，这表明该母羊内在的母性关怀存在潜在基础。对苏格兰黑脸羊和萨福克母羊的研究表明，与母性关怀较差的母羊相比，表现出高水平母性关怀的母羊在妊娠后期血浆雌二醇水平升高，并且循环雌二醇浓度与母性行为相关。尽管母性行为的遗传基础仍有待充分确定，但通过选择有可能改善母性行为，更好地理解母性行为个体差异背后的神经内分泌过程可能有助于制定选择策略。此外，对具有一定遗传基础的羔羊行为进行选择，也可能是提高羔羊存活率的一条途径。由于母羊和羔羊的行为都受到环境因素的影响，在怀孕和分娩期间进行适当的管理将增强母性行为的表达和羔羊的活力，从而有助于提高羔羊存活率。
