Esmailnejad, A. & G. Nikbakht Brujeni, 2018. Allelic polymorphism of insulin-like growth factor I gene and its association with production traits in native chickens. Bulg. J. Vet. Med., 21, No 3, 279–285.

DOI: 10.15547/bjvm.1072

Insulin-like growth factor 1 (IGFI) is an essential regulator of growth, cell proliferation/differentiation and protein synthesis in a variety of cell types. IGFI is considered as one of the most important candidate genes controlling production and reproduction traits in chickens. This locus could be linked to the highly effective genes affecting egg production and growth traits. The aim of present study was to investigate the IGFI gene polymorphism and its association with growth and egg production traits in Iranian native chicken. A total of 313 blood samples were collected from the Native poultry breeding centre, Khorasan province, Iran. Single nucleotide polymorphism (SNP) of the IGFI 5'-UTR was detected by PCR-RFLP method and PstI restriction endonuclease enzyme. Finally, the SNP was confirmed by sequencing of RFLP profiles. Association between IGFI alleles and production traits was evaluated using multivariate regression analysis and GLM procedures. Two alleles A (PstI –) and B (PstI +) and three genotypes (A/A, A/B and B/B) were identified for the IGFI gene. Allele B was the most frequent (60.1%) and considered as reference allele for association study. A/B genotype was significantly correlated with lower first egg weight and higher egg laying intensity compared to B/B and A/A genotypes. No significant association was observed between IGFI genotypes and other production traits including egg weight, weight of sexual maturity and body weight. These results suggest that there is a possibility of IGFI genotypes acting as a genetic marker for selecting some egg production traits in native chickens.

Key words: chicken, IGFI, Iran, production traits