The Association Of Polymorphisms Of LEP Gene And STAT5a Gene With Milk And Body Traits In Lanshan Daiiy Goat

Milk traits is the economically important traits of dairy goat.The breeding improvementof milk traits is limited by conventional breeding technology in Dairy Goat,because theheritability of milk traits is very low.So it is necessary to improve the accuracy of selectionand breeding efficiency of dairy goats with the marked assisted selection. Explore the geneticvariation and interaction of LEP and STAT5a gene in Laoshan dairy goat and its associationwith production traits. There are174lactating ewe of dairy goats in Laoshan. DNA poolingtechnology and candidate genes by direct sequencing technology was used to detect thepolymorphisms in exon2, exon3of LEP gene and exon10, exon16of STAT5a gene. Geneticdiversities of polymorphism sites were analyzed by R program, and the association ofploymorphisms with milk traits and growth traits were analyzed through SAS9.1program.Theresults as follows:(1) There was no polymorphism on exon2,3of LEP gene and exon10,16of STAT5agene, which is different from dairy cow. One mutation site was detected at intron2of LEPgene, which is the A/G of locus L393located in intron2. The PIC of Laoshan dairy goatpopulation is0.3554, which belongs to an intermediate polymorphism.This site deviates fromHardy-Weinberg equilibrium (P<0.05). There were two chain mutations on intron9ofSTAT5a gene, which is the A/G of locus S163and the C/T of locus S206located in intron9.The genotype and allele frequencies of the two sites are the same. The PIC of Laoshan dairygoat population is0.3310, which belongs to an intermediate polymorphism.The two sites arein Hardy-Weinberg equilibrium (P>0.05).(2) Significant test for milk composition, model and groups effects were significantlevel(P<0.05); three SNPs loci on milk composition did not reach a significant level;Theinteraction on milk composition of groups with L393, groups with S163/S206, L393with S163/S206did not reach a significant level. Milk yield of L393locus was significant(P<0.05),and the interaction on milk yield of L393with S163/S206did not reach a significantlevel.Model and groups had a significant effect on growth traits. S163/S206loci had asignificant (P<0.05) effect on body weight, body length and heart girth.The interaction ofgroups with L393had a significant (P<0.01or P<0.05) effect on body height and rump width.The interaction of groups with S163/S206had a significant (P<0.05) effect on heart girth.S163/S206, the interaction of groups with S163/S206all had a significant (P<0.05) effect onheart girth, but the effect of groups was not significant on heart girth.(3) Analysis associated with milk traits of Laoshan Goats, the milk yield at300d trait ofthe GG genotype was significantly (P<0.05) higher than AG and AA genotype on L393loci.The additive effect of milk yield at300d was significant (P<0.05) and the substitutioneffect was a significantly (P<0.01) negative value. Allele G had a positive effect on milk yieldat300d.(4) Analysis associated with growth traits of Laoshan Goats, the body weight and bodylength trait of the GG/CC genotype was significantly (P<0.05) higher than AG/CT andAA/TT genotype on S163/S206loci in the whole group. The heart girth of GG/CC, AG/CTgenotype was significantly (P<0.05) higher than AA/TT genotype on S163/S206loci. Theadditive effect of body weight, body length and heart girth were significant (P<0.01) and thesubstitution effect was a significantly (P<0.05or P<0.01) negative value. Allele G/C had apositive effect on the three traits.The heart girth of GG/CC, AG/CT genotype was significantly (P<0.01) higher thanAA/TT genotype on S163/S206loci in P group. The additive effect of heart girth wassignificant (P<0.01) and the substitution effect was a significantly (P<0.01) negative value.Allele G/C had a positive effect on heart girth.The rump width of GG genotype was significantly (P<0.05) higher than AA genotype onL393loci in F group. The additive effect of rump width was significant (P<0.05) and thesubstitution effect was a significantly (P<0.05) negative value. Allele G had a positive effecton rump width.The body height of AA and AG genotype was significantly (P<0.01) higherthan GG genotype on L393loci in P group. The additive effect of body height was significant (P<0.01) and the substitution effect was a significantly (P<0.05) positive value. Allele A had apositive effect on body height.Results from this study show that the candidate gene LEP and STAT5a haspolymorphisms in Laoshan dairy goat and a significant effect on milk traits and growth traits,so they could provide valuable genetic markers to breed of Laoshan dairy goat.