小尾寒羊母性行为投入差异及其调控机制研究

小尾寒羊具有性成熟早、常年发情、一胎多羔等优良性状，是我国乃至世界著名的高产绵羊品种。目前，断奶前羔羊的较高死亡率是小尾寒羊规模化养殖中亟待解决的难题之一，制约了小尾寒羊养殖业的发展。良好的母性行为投入是提高多胎羔羊成活率的关键，然而，目前关于小尾寒羊对多胎羔羊个体母性行为投入差异及其内分泌、分子机制尚不清楚。因此，本项目以产2-3羔初经产母羊为研究对象，通过母性行为投入观测，明确母性行为投入差异及与羔羊生长的关系；通过母羊血浆中雌二醇、催产素、皮质醇水平检测，解析与母性行为投入密切相关的激素；进而探讨激素作用的相应受体DNA甲基化，揭示DNA甲基化与受体基因表达的关系。综合分析以上研究结果，从行为—内分泌—分子水平系统阐述小尾寒羊母性行为投入差异及其调控机制，为提高羔羊成活率，改善动物行为性状提供理论依据。

The Small-Tail Han sheep is a famous prolific sheep breed in our country and even all over the word. This sheep breed has many excellent characteristics such as precocity, non-seasonal estrus, multiple litters and so on. Currently, the higher mortality rate of lambs before weaning restricts the development of Small-Tail Han sheep industry which is one of the most difficult problems to be solved. Good maternal behaviour input is a key to improve survival rate of multiparous lambs. However, the differences of maternal behaviour input and its endocrine, molecular mechanism in Small-Tail Han sheep to multiple lambs are still unknown. Therefore, this research project will take primiparous and multiparous ewes with twin or triplet lambs as research objects and will clarify the relationships between the input differences of maternal behaviour and lambs growth by maternal behavior observation. Then, the hormones that are related to maternal behavior input will be expounded by detection of the estradiol, oxytocin and cortisol levels in ewe plasma. Thirdly, this project reveals that the relationship between mRNA expression and DNA methylation of hormone receptors. Synthesizing all the results from aforementioned behaviour, endocrine, and molecular levels, this project reveals the differences of maternal behaviour input and its regulation mechanism in Small-Tail Han sheep. This research will provide theoretical basis for improving the animal behavioral traits and lamb survival rate.