【作者】 夏华强；

【导师】 柳小春；

【作者基本信息】 湖南农业大学 ， 动物遗传育种与繁殖， 2004， 硕士

【摘要】 本试验以7个猪群(杜洛克猪、长白猪、大白猪、长大杂猪、宁乡猪、沙子岭猪、大围子猪)共659头猪为研究对象，采用聚合酶链式反应—限制性片段长度多态性(PCR—RFLP)分析了激素敏感脂肪酶(HSL)基因外显子Ⅰ、黑皮质素受体-4(MC4R)基因的遗传多态性及基因型频率与基因频率，并对品种内基因型频率的分布进行卡方检验；结合生长性能记录、屠宰记录，研究了MC4R基因对生长性状、胴体性状、肉质性状的影响，主要结果如下：一．激素敏感脂肪酶(HSL)基因外显子Ⅰ 检测的5个猪群中，(1) 在大白猪、长白猪中不存在变异，均表现为GG基因型，只有等位基因G。(2) 在杜洛克猪和地方品种(大围子猪和宁乡猪)中，存在AA基因型、AG基因型和GG基因型，等位基因A的频率分别为0.3979、0.7272、0.7295。(3) 在外来品种中有更多的等位基因G，在地方品种中有更多的等位基因A。二．黑皮质素受体-4基因(MC4R基因) 1、检测的6个猪群中，(1) 外来品种MC4R基因存在AA基因型、AB基因型、BB基因型，等位基因A的频率分别为0.6301、0.2600、0.5141、0.3889。(2)大围子猪、沙子岭猪两个地方品种中均表现为BB基因型，只有等到位基因B。 2、MC4R基因对生长性状的影响：(1) MC4R基因对达100kg日龄、活体平均背膘厚、活体校正背膘厚、生长性能指数都有一定的模型效应；(2) 等位基因A具有降低活体平均背膘厚，提高生长性能指数的作用。 3、MC4R基因对胴体、肉质性状的影响：本研究发现，(1) 所有性状都有一定的模型效应；(2) AA基因型的实测平均背膘厚比BB基因型的薄，脂肪率比BB基因型的低，瘦肉率比BB基因型高。AA基因型对实测平均背膘厚、脂肪率具有负效应，对瘦肉率具有正效应。肉色等级、大理石纹以AB基因型最好。 以上表明：HSL基因外显子Ⅰ存在多态性、MC4R基因多态对猪生长、胴体、肉质性状有一定影响，研究结果可以作为瘦肉型猪选育的理论依据。更多还原

【Abstract】 Adopting Polymerase Chain Reaction-Restrain Fragment Length Polymorphism (PCR-RFLP),the genetic variation of Hormone-sensitive lipase(HSL) gene exon I and Melanocortin-4 Receptor (MC4R) gene were detected in 659 pigs including 7 population (Duroc, Landrace, Yorkshire, LY, Ningxiang, Shaziling, Daweizhi),then genotype frequencies and gene frequencies were counted according to the PCR-RFLPs and the distribution of genotype frequencies in the population were analyzed by Chi Square Test. The effects of MC4R gene on Growth traits , Carcass traits and Meat quality traits were estimated .The main results were showed as follows:1.Genetic polymorphism of HSL gene exon I:The distribution of genotype is significantly different among 5 breeds. There exist only GG genotype in lean-type Large White and Landrace pigs. Duroc and native breeds (ningxiang and daweizhi) have three genotypes (AA AG GG), allele A frequencies of three breeds is 0.3979,0.7272,0.7295 respectively. While there are higher frequencies of allele G in the foreign breeds, there are higher frequencies of allele A in the native breeds.2.Genetic polymorphism and effect of MC4R gene(1) The distribution of genotype is significantly different among 6 breeds. In four foreign breeds, there are three genotypes (AA AB BB ) , allele A frequencies of four breeds is 0.6301,0.2600,0.5141,0.3889 respectively .There exist only BB genotype in fat-type Shaziling and Daweizhi pigs.(2) There are considerable model effects on 100kg days, Loving Mean BFT, Loving modified BFT, Growth Index. The allele A has effects of reducing Loving BFT and enhancing Growth Index. But the effects are different in different breeds.(3) Among all carcass traits and meat quality traits, there are considerable model effects. In there genotypes, Real mean BFT and Fat Percentage of the pigs with genotype AA are lower than that of the pigs with genotype BB, while the Meat percentage of the pigs with genotype AA is higher than that of the pigs with genotype BB. Genotype AA performs negative effects on Real mean BFT, Fat Percentage and positive effects on Meat Percentage .As Marble Score and Meat Color Score are concerned, the pigs with genotype AB are better than the others.The purpose of this study is to provide theory basis for improving the Growth traits, Carcass traits and Meat quality traits更多还原