Association Analysis Of α-La, β-Lg Gene Polymorphisms With Milk Production And Body Size Traits In Dairy Goat

The bioinformatics, DNA sequencing, DNA sequence analysis and PCR-SSCP techniques were applied to analyze the genetic variations ofα-la andβ-lg gene and their association with economic trais in 708 goats, which comprised of Xinong Sannen dairy goat and Guanzhong dairy goat. The two key function gene includedα-la (α- lactalbumin)gene (exon 1～4 and 5'UTR),β-lg(β-lactoglobulin) gene (exon 2,4,5 and 5'UTR). At the same time the genetic polymorphism and its relationship with body size traits (body height, body length and chest), and milk production traits (first fetal yield and second fetal yield) analyzed on the two breeds. The purpose is to obtain the corresponding molecular genetics information, finding the molecular markers which have relationship whit body size traits and milk production traits of, and provide a scientific basis for improvement of economic traits .This study obtained the following important findings :1. Association between genetic variations of goatα-la gene and economic traits in dairy goatWe detected Xinong Saanen dairy goats and Guanzhong dairy goatα-la gene exons 1-4 and part of 5 'flanking region in this study, and its relationship between with the body size and milk production traits .(1). We found three SNP inα-la gene of dairy goat.Among the five locus, contrast with the NO_X06366, three mutations were detected:α-la-â… loci exists C> T mutation of the phenomenon (NO_X06366: g.875 C> T ). In theα-la-â…¡loci also exists C> T mutation of the phenomenon (NO_X06366: g.1273 C> T). Inα-la-â…¢gene locus there is a A> G mutation of the phenomenon (NO_X06366: g.1738 A> G), the above three polymorphic loci are all in Hardy-Weinberg equilibrium (P> 0.05).(2).We found that the different genetypes has relations with the body size in two dairy goat breeds.In the Guanzhong dairy goatα-la-â… locus, CC genotype had lower Chest Circumference than CT and TT genotypes significantly (P <0.05) , and there is no significant difference in CT and TT genotype. In the body length and body height of these two indicators among the three genotypes showed no significant difference.In theα-la-â…¡gene locus, the body length of the CT,TT genotype was significantly higher than CC genotype (P <0.05),there are no significantly difference on the body height between three genetypes..In theα-la-â…¢gene locus, the body height on the GG genotype significantly higher than t GA and AA genotypes (P <0.05). In the body length on the GG genotype was significantly higher than GA and AA genotypes (P <0.05), and GT also significantly higher than TT genotype. In the Chest Circumference, GG genotype was significantly higher than GA (P <0.01), GG genotype is significantly higher than AA (P <0.05), GA and AA showed no significant difference.In the Xinong Sannen dairy goatα-la-â… locus, CC genotype had lower Chest Circumference than CT and TT genotypes significantly(P <0.05) ,and there is no significant difference in CT and TT genotype.There are no significantly diference between the milk production and body size triat.Inα-la-â…¡locus, TT genotype had higher body height and body length than CC and CT genotypes. There are no difference on the milk production and other body size trait.(3). We found that the GG genotype had higher milk trait (the first fetal milk yield and the seconde fetal milk yield )than GA and AA genetypes(P<0.05) onα-la-â…¢locus for Saanen dairy goat.2. Association between genetic variations of goatβ-lg gene and economic traits in dairy goatWe detected Xinong Saanen dairy goats and Guanzhong dairy goatβ-lg gene three loci and part of 5 'flanking region and the genetic variation and its relationship with body size and milk production traits between in this study.(1). We found two SNP inβ-lggene of dairy goat.Contrast with the NO_X06366, inβ-lg-â…¡locus one G>A mutation was detected (NW₀01493004: g.913G>A). There are three genotypes be detected in the two goat breeds, named GG,GA and AA and all in Hardy-Weinberg equilibrium (P> 0.05). In 5 'flanking region one G>T(NW₀01493004: g.-427G>T)mutation and three genotypes were detected.(2). We found that the different genetypes has relations with the body size in two dairy goat breeds. In the Guanzhong dairy goatβ-lg-â…¡locus, AA genotype had higher body height and body length than GA. In 5 'flanking region locus, deffirent genotype showed no significant difference. Inβ-lg-â…¡locus of Xinong Sannen dairy goat, AA genotype had higher body height and than GA and no significant difference in the body length and heart girth. In production traits (the first fetal milk yield and the second fetal milk yield), defferent genotype showed no significant difference.(3). We found thatβ-lg-5'-UTR of the GG-type can be used as the molecular markers for the first fetal milk yield and the second fetal milk yield.In 5 'flanking region locus, the individuals with genotype GG were significant higher than genotype GT and TT (P<0.05) in the production traits, as the second fetal milk yield too.It implied that the GG type can be used for improve milk production as the preferred marker locus.