| Growth traits are one of the important economic traits of chickens and researching the growth and development of chickens and slelecting SNP markers related to chicken growth are significant works for improving growth traits.Wenshang Barred Chicken is an excellent local breed,but the growth and developent of the relevant research has not been reported.In this study,the growth data of 0-50 weeks was measured with 1000 purebred Wenshang Barred Chicken including four strains.First of all,by comparing the weight and size of the four strains,we can understand the difference of the growth indexes of the four strains.Followed by the use three models including Logistic,Gompertz,Bertanlanffy,its weight and shank growth curve were fitted.Finally,the growth genes of pituitary axis,the genes of skeletal muscle development and the genes of energy metabolism were selected as candidate genes,and the association analysis of SNP and growth traits was studied.The results are as follows:(1)In prensent study,we compared the body weight and body size of the four populations of Wenshang Barred Chicken.The results showed that the body weight and body size were not different in large and small scale feathers in birth(P>0.05).At 6 weeks of age,there was no significant difference in body weight and body size between fast and slow feathers(P<0.05),only chest width,body length,keel length and chest depth were significantly different in size(P<0.05);At 12,18,30 weeks of age,body weight and size were mainly significant difference between large size and small size(P<0.05).(2)Three models including logistic,Gompertz and Bertanlanffy were used to fit the body weight and shank growth of large and small body.The results showed that the three models could fit the growth curve of body weight,shank length and shank width of Wenshang Barred chicken and fitness degree were above 0.97.The logistic and Gompertz models were found to fit the weight of the large cock and hen,respectively,compared with the actualmeasured values and Gompertz model is the best fit for body weight of small body;Gompertz model is the best fit for shank length of large body;Bertanlanffy model is the best fit for shank length of small body;Bertanlanffy model is the best fit for shank width of small and large body.(3)In present study,16 genes such as GH,IGF-1,IGF-2,IGF1 R,GHRL,Myf5,MyoG,MSTN were selected as candidate genes.The SNPs reported in the literature were studied in this experiment.First,the SNPs in the population were screened by mixing pooling,and then the SNPs of the candidate genes were genotyped by mass spectrometry.By constructing the general linear model,the effect of SNP on growth traits was studied by least squares method.The results showed that there were SNPs reported in the literature,and the genetic analysis showed that most of the SNPs belonged to moderate polymorphism in the experimental population and accorded with the Hardy Weinberg equilibrium.The results of association analysis showed that rs3138025 in GH gene was significantly correlated with shank length,shank width,body length and keel length growth(P<0.05),and the contribution rate of this site to phenotypic variance was 1.02%-3.80%;rs316492824 in IGF-I gene was significantly correlated with body weight,shank width,body length,chest width and keel length(P<0.05),and the contribution rate of the locus to phenotypic variance of these growth traits was 1.37%-3.51%;rs313810945 in IGF-II gene was significantly correlated with the growth of body weight and body size(P<0.05),and the contribution rate of the locus to phenotypic variance of these growth traits was 1.17%-2.56%;rs737328551 in PIT-1 gene was significantly correlated with the growth of body weight and body size(P<0.05),and the contribution rate of phenotypic variance of growth traits was more than 1.43%.rs314431084 in MSTN gene was significantly correlated with body weight,shank length,shank width,body length and chest depth(P<0.05),and the contribution rate of phenotype variance was 1.01%-2.54%;rs29009236 in MyoG gene was significantly associated with body weight,shank length,shank width,body length,keel length and chest width(P<0.05),and its contribution rate to phenotypic variance was 0.97%-2.97%;rs14133282 and rs13585312 in PRKAG2 gene was significantly correlated with the body length and keel length(P <0.05),and its contribution rate to the phenotypic variance was 1.08%-1.83%.In summary,there was no significant difference in body weight and body size at earlygrowth stages,but as the age increases,there is a difference in body weight and body size between large and small size and there is little difference between fast and slow feathers.Logistic,Gompertz and Bertanlanffy models were able to fit the body weight and shank growth curve.The SNPs of GH,IGF-I,IGF-II,PIT-1,MSTN,MyOG and PRKAG2 genes were significantly correlated with the growth traits,and these significant SNPs can be applied to actual breeding as a significant marker of the effect of growth traits. |
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