Effect of IGF1 gene polymorphism and expression levels on growth factors in Indian colored broilers

Single nucleotide polymorphism (c. 570 A→C) in chicken IGF1 gene promoter has been reported to be associated with production traits. The present study was aimed to detect the effect of this polymorphism on the expression of different growth factors and receptors in Indian colored parent line broilers. An array of economic traits body weights, conformation traits, carcass traits and cutup parts were also recorded among different genotypes (AA, AB and BB). Expression analyses of seven genes i.e. insulin like growth factor 1 (IGF1), insulin like growth factor 2 (IGF2), insulin like growth factor 1 receptor (IGF1R), growth hormone receptor (GHR), insulin like growth factor binding protein 2 (IGFBP2), myostatin (MSTN) and transforming growth factor beta 2 (TGFβ2) were carried out in liver and breast muscle of broilers with different genotypes. All the genes exhibited higher expression in hepatic tissue of AA and AB genotypes than BB genotypes. However, except MSTN and TGFβ2 the expression was higher in BB genotype. AA and AB genotypes exhibited significantly higher performance than BB genotype. The present results indicated that the single nucleotide polymorphism (SNP) present in the promoter region of IGF1 could modulate the effects of polymorphism on the expression of genes present on somatotropic axis as well as other growth regulating factors. These results also suggested that endocrine manner of IGF1 is important than para/autocrine mode of action during post-hatch growth of colored broilers.