【作者】 石国庆；

【导师】 刘守仁； 杨利国；

【作者基本信息】 南京农业大学 ， 动物遗传育种与繁殖， 2006， 博士

【摘要】 绵羊的多胎性状是养羊业获得更多经济效益的重要途径。近年来在澳大利亚Booroola羊发现其存在多胎基因（FecB），并对其遗传特点、遗传效应等进行了广泛研究。随后的几年内，以其为候选基因在不同国家的绵羊品种中进行了更为广泛的发掘，我国在湖羊和小尾寒羊两个品种中都检测到了该基因，但是多胎基因在维持多胎妊娠方面的生物学作用、生理生化特点及对激素分泌水平在品种间、品种内的关系和影响一直没有明确的报道。为提高绵羊繁殖力，降低多胚移植和多胎绵羊胚胎早期死亡率，很有必要以绵羊子宫内环境为重点从组织学、生理学及生殖激素水平进行检测，从而找到多胎绵羊在生殖中的某些规律，以便为控制绵羊的多产性状奠定理论依据。 本研究应用放射免疫测定、核酸分析、基因标记等技术，主要对湖羊多胎性状进行深入研究，同时以中国美利奴新疆军垦型细毛羊为对照进行研究，从理论上充实绵羊繁殖妊娠生理机制，对提高绵羊产羔率、减少胚胎死亡和提高养羊业经济效益有重要意义。主要内容如下： 1 绵羊妊娠早期的激素分泌水平 以研究江苏湖羊多胎机制为目的，应用放射免疫测定、核酸分析、基因标记等分析技术，并以中国美利奴新疆军垦型单胎母羊为对照，通过分析比较母羊的发情周期和妊娠早期外周血中促卵泡素（FSH）、瘦素（Leptin）、前列腺素F_2α(PGF_2α)、孕酮（P₄）和17β-雌二醇（E₂）水平、胎盘子叶DNA和RNA及葡萄糖含量来分析比较多胎湖羊与单胎中国美利奴新疆军垦型母羊的差别，结果表明：两者之间17β-雌二醇（E₂）峰值与发情持续期相关差异不显著（P＞0.05）。而外周血中孕酮（P₄）、雌二醇（E₂）和前列腺素（PG）浓度的平均谷值和促卵泡素（FSH）、促黄体素（LH）的峰值差异水平分别达到极显著（P＜0.01）和显著水平（P＜0.05）；瘦素水平均值差异达到极显著水平（P＜0.01）。因此，推测瘦素水平含量的不同直接影响绵羊是否怀孕以及单或双胎，或是因绵羊怀孕因单胎或双胎不同而使瘦素水平含量升高。 2 绵羊妊娠早期子宫内环境研究 采用解剖学方法和生化方法研究绵羊妊娠早期的胎儿重量、体长和母体的卵巢重量、子叶数量和DNA含量的差异，结果表明：胎儿重量差异显著（p＜0.05），胎儿长度差异不显著（p＞0.05），卵巢重量左右差异不显著（p＞0.05），子宫子叶大与-+-+大和小与更多还原

【Abstract】 The trait of prolificacy of sheep was an important approach increasing more economic benefit. In recent years, a major gene （FecB） controlling sheep prolificacy in Booroola in Australia was fond, and its genetic traits, genetic effects and other characters were widely studied. During several years after this find, FecB gene was widely studied as a candidate gene in many countries in different sheep breeds. The FecB gene was found in Hu and little Han in our country, which were two famous prolific sheep breeds in the world. To date, about the biological effects, bio-chemical characters and effects on hormone secretion of FecB gene in different breeds or different animals in the same population had no clear reports. To increase litter size and decrease mortality rate of early embryos, the study on uterus inner conditions from histology, physiology and reproduction hormone level must have been processed. It may be some rules were found about prolific sheep breeds and to provide a method for molecular marker assistant breeding.Many technologies, such as RIA, nucleic analysis, gene marker assistance and so on were used to in this experiment study prolific trait of Hu, and using China Merino Xinjiang reclaimation sheep as control, to enrich the theory of sheep reproduction mechanism, this study had important significance for increasing litter size and decreasing embryos mortality and increasing economic benefits for sheep breeding. The main contents presented as follows:1. Study of the level of hormone in early pregnancy of sheepTo study the prolific mechanism of Hu Sheep in Jiangsu province, many techniques such as RIA, nucleotide analysis, gene marker analysis and so on were used in this experiment to study prolific trait of Hu Sheep, and using China Merino Xinjiang reclaimation sheep as control. Many effect factors on sheep reproduction were studied between Hu and control group, such as oestrus cycles, level of FSH, Leptin, PGF_2α, progesterone and estradiol in blood of outer blood vessel and content of DNA and RNA or更多还原