Polymorphisms in Exon 2 of IGF-IR Gene and Theirs Association with Production Traits in Jinghai Yellow Chicken

In this study, exon 2 of Insulin-like Growth Factor Receptor type I (IGF-IR) gene was studied as a candidate gene associated with production performance in Jinghai Yellow chicken. A pair of primers was designed to screen the Single Nucleotide Polymorphisms (SNPs) using DNA pooling which consisted of DNA from all 200 female chickens and three pairs of primers were then designed to check them individually. The result showed there were three SNPs (G26333A, G26336A and C26639T) in the chicken group, each had three genotypes and was in. Hardy-Weinberg equilibrium (p>0.05). Correlation analysis showed the G to A transition at 26333 bp was negatively associated with 300 days egg number and body weight at 4 and 16 weeks of age, the G to A transition at 26336 bp was positively associated with body weight at 8 and 12 weeks of age and the C to T transition at 26639 bp was positively associated with body weight at 16 weeks of age. Com-genotype analysis showed that the age at the first egg of chickens with AA/CD/EE was earlier than those with AA/CC/EE and AB/CC/EF (p<0.05) and chickens with AB/CC/EE had more 300 days egg number than those with BB/CD/EE (p<0.05). AA/CC/EF was an enhancing com-genotype for body weight while AA/CC/EE and AB/CC/EF were the negative ones at 12 and 16 weeks of age. The results suggested a significant association between SNPs of IGF-IR gene and production traits and these SNPs could be used as potential genetic markers in future breeding of Jinghai yellow chicken.