Genetic Analysis of SNPs in GH, GHR, IGF-I and IGFBPII Genes and their Association with Some Productive and Reproductive Traits in Native Breeder Hens

Abstract

The aim was to study the polymorphisms in GH, GHR, IGF-I and IGFBPII genes and their association with productive and reproductive traits. DNA was extracted from blood samples of 380 breeder hens of Mazandaran native fowls breeding station by modified salting out method. For genotyping, PCR products of GH, GHR, IGF-I and IGFBPII loci were digested with specific restriction enzymes. We found six genotypes of AA, BB, CC, AB, AC and BC with the frequency of 0.10, 0.01, 0.36, 0.07, 0.34 and 0.12 in GH, two haploid alleles and genotypes of B+ and B-with the frequency of 0.72 and 0.28 in GHR, three genotypes of BB, Bb, bb with the frequency of 0.49, 0.44 and 0.07 in IGF-I and three genotypes of CC, CT and TT with the frequency of 0.14, 0.62 and 0.24 in IGFBPII loci, respectively. Significant associations were found between SNPs in IGF-I locus and egg number at 120-270 and 345-375 days of age, egg weight at puberty and percentage of hatchability traits (P<0.05). We also found significant effects of GHR and IGFBPII loci on egg number at 345-375 days of age and average egg weight at 345-375 days of age traits, respectively (P<0.05). Mean comparisons analysis between different genotypes of GH gene for body weight at day one and puberty, age at sexual maturity, egg weight at puberty and 30 weeks of age, average egg weight and egg number at 345-375 days of age and also percentage of fertility traits and IGFBPII genotypes for laying intensity trait were observed to be significant (P<0.05). Regarding the significant effects of GHR, IGF-I and IGFBPII genes on egg production traits, it could be resulted that these candidate genes may be used as the candidate markers in poultry breeding programs to improve productive and reproductive traits in this population.