Study On The Relationships Between SNPs Of Myostatin Gene & IGF-â…  Gene And Carcass Traits In Chicken

Myostatin gene and IGF—Ⅰgene were selected as candidate genes affecting carcass traits in chicken in this study, where two loci in the first exon 1 of Myostatin gene and six loci in IGF—Ⅰgene in 180 Wenling grass-chicken including 3 lines (I.e. line C,A and B ) were detected by PCR—RFLP, and its genetic effects on carcass traits were also analyzed.The results showed that 2 genotypes (MN and NN) in G(2100)A locus were identified by Bsh1236Ⅰand 3 genotypes (AA,AB and BB) in G(2109)A locus were identified by MspⅠin Myostatin gene, and 5 genotypes were made by corn-analyzing 2 loci. The x~2 test for Hardy—Weinberg equilibrium indicated each line and the population was not at the Hardy—Weinberg equilibrium (P≤0.01) in both loci. The analysis of variance showed that the different genotypes had significant or suggestive deviation (P≤0.01 or 0.01＜P≤0.05) in carcass percent. The multiple comparisons were made. The abdominal fat weight and carcass percent of heterozygosis MN were suggestively higher (0.01＜P≤0.05) than that of mutant NN, and the breast muscle weight and breast muscle percent of heterozygosis AB were significantly or suggestively higher (P≤0.01 or 0.01＜P≤0.05) than that of AA individuals. In addition, the abdominal fat weight and abdominal fat percent of AA individuals were significantly higher (P≤0.01) than that of mutant BB individuals, but BB individuals were suggestively lower (0.01＜P≤0.05) than AA and AB individuals in leg muscle weight trait. The abdominal fat weight and abdominal fat percent of genotype NA/MA individuals were significantly higher (P≤0.01) than other genotype individuals while com-analyzing 2 loci. And NA /MA individuals were significantly lower (P≤0.01)than other genotype individuals in breast muscle percent, were suggestively lower(0.01＜P≤0.05)than NA/MB individuals. The allele B had additive effect on breast muscle weight and breast muscle percent while adverse effect on content of fat. There were no polymorphisms in TasⅠand Mph1103Ⅰloci identifying products amplified by primer IS1IA1 and in HinfⅠlocus identifying products amplified by primer IS2IA2 in IGF—Ⅰgene. The mutations of C→A,C→T and T→C in products amplified by primer IS1IA1, IS3IA3 and IS4IA4 were identified by HinfⅠ,TaqⅠand PstⅠin IGF—Ⅰgene, respectively. Three genotypes were acquired in each locus and seven genotypes were made by com-analyzing PstⅠand HinfⅠlocus. Line A was at the Hardy—Weinberg equilibrium (P＞0.05) in each locus, but line B in PstⅠlocus and line C in TaqⅠlocus were not at the Hardy—Weinberg equilibrium (P≤0.01 or 0.01＜P≤0.05). The analysis of variance showed that the genotypes of each locus had significant or suggestive difference (P≤0.01 or 0.01＜P≤0.05) in partial carcass traits. The multiple comparisons indicated the least squares means of 3 genotypes in each locus had the property of mutant genotype＞heterozygous genotype＞wild genotype in body weight, carcass weight, semi—eviscerated yield weight, eviscerated yield weight, breast muscle weight, leg muscle weight. The com-genotypes QF/QF and QE/QF were suggestively higher (0.01＜P≤0.05) than PE/QE in 4 carcass traits. The mutant alleles (I.e. F,T and Q) in HinfⅠ,TaqⅠand PstⅠloci and haplotype QF had additive effect on carcass traits while PE had adverse effect on them.The genetic distance between line A and B was 0.0053, indicating they were in the same branch through cluster analysis.