| Many genetic factors influence the growth, feed intake and feed efficiency of birds. In the current study we evaluated the association of49previously reported SNPs in9candidate genes (LEPR, PRKAB1, PRKAG2, PRKAG3, MTOR, PDPK1, NPY6R, INS, and GH) with body weight (BW), body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR).27SNPs with a very low minor allele frequency were removed due to genotype quality control and data filtering. The experimental population consisted of796pedigreed males from2genetically unrelated yellow meat-type chicken strains,335chickens for N202and461chickens for N301. Body weight at49(BW49) and70days of age (BW70) and FI (from49to70days of age) were measured individually. BWG and FCR were calculated based on BW and FI in the interval between49to70days. The results for each gene are as followings:1. LEPR:rs14657368was significantly associated with BWG and FCR in both strains (P<0.05), and together rs13684613and rs14657336were significantly associated with FI in both strains (P<0.05). These significant associations were consistent in both strains, and validated the results. However, rs13684616was associated with FI in both strains (P<0.05) but has opposite genetic effects among the two strains. In addition, some of the SNP-trait associations were detected in only one strain. Indeed, rs13684613, rsl4657336, rsl3684616, and rs13684623were significantly associated with BW only in N202strains (P<0.05) and rs14657368was significantly associated with BW only in N301strain (P<0.05). Furthermore, rs13684623was significantly associated with FI only in the N202strain (P<0.05), rs13684615was significantly associated with FI just in the N301strain (P<0.05) and rs13684616was significantly associated with FCR just in the N301strain (P<0.05). Besides, haplotypes for the strong LD block based on rs14657336, rsl3684613, rs13684615and rs13684616were reconstructed and haplotype association analysis indicated that the LD block was significantly associated with BW and FI in the N202strain and FCR in the N301strain (P<0.05).2. PRKAB1:rs14094358and rs14094362were significantly associated with BW, BWG and FI only in N202strain (P<0.05) and rs14094361was significantly associated with FI and FCR just in N301strain (P<0.05). As well, rs14094363was significantly associated with FCR only in the N301strain (P<0.05). For the PRKAB1gene, the four SNPs were associated with traits only in one strain and the genotype effects of the SNPs were strain-specific.3. PRKAG2:the results implied that rs14133282was significantly associated with FI only in N202strain (P<0.05) and rs13535812was significantly associated with BW just in N202strain (P<0.05). The genotype effects of those SNPs were strain-specific.4. PRKAG3:rs13595570was significantly associated with BW in N202strain (P<0.05) and significantly associated with FI and FCR in N301strain (P<0.05). The results suggested that the genotype effects of this SNP were strain-specific.5. mTOR:rs14284557was significantly associated with FI just in N202strain (P<0.05). This association implies that genotype effects of this SNP were strain specific.6. PDPK1:Snp.23.302.41339.S.1and rs14075742were significantly associated with BW in both strains (P<0.05). These significant associations were consistent in both strains, and validated the results. However, Snp.23.302.41339.s.1and rs14075742were associated with FI in both strains (P<0.05) but with opposite genetic effects in the two strains. Besides, Snp.23.302.41339.s.1and rs14075742were significantly associated with BWG only in N301strains (P<0.05). Thus, the genotype effects of the two SNPs for BWG were strain-specific.7. NPY6R:Snp.31.298.3106.S.1and rs14062577were significantly associated with BW in N202strain (P<0.05) and rs14062576was significantly associated with BW in N301strain (P<0.05). As well, Snp.31.298.3106.S.1and rs14062576were significantly associated with FI only in N301strain (P <0.05) and rs14062577was significantly associated with FI just in the N202strain (P<0.05). Moreover, Snp.31.298.3106.S.1was significantly associated with FCR just in the N301strain (P<0.05). The three SNPs in NPY6R were associated with traits only in one strain. These results indicated that genotype effects of those SNPs were strain-specific.8. INS:rs13757636was significantly associated with FI, FCR and BW in both strains (P<0.05). These significant associations were consistent in both strains, and validated the results.9. GH:the detected SNP-trait associations were in only one strain. Indeed, rs13401485was significantly associated with BW and FI in N301strain (P<0.05). However, Snp.101.6.287.S.1was significantly associated with BW and FI in N202strain (P<0.05). The results suggested that genotype effects of those SNPs were strain specific.As a whole, the examined polymorphisms of the9genes (LEPR, PRKAB1, PRKAG2, PRKAG3, MTOR, PDPK1, NPY6R, INS, and GH) were associated with BW, BWG, FI, and feed efficiency in chicken. Our findings confirm the importance of the studied genes in regulating growth, feed intake and feed efficiency and provide research basis for further investigations. The studied polymorphisms might be used as potential breeding genetic markers in meat-type chicken. |
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