Abstract

Growth hormone axis and the transforming growth factor-b subfamily are the most important groups of genes that are involved in a wide variety of physiological functions such as growth and reproduction. As no information about the allelic characterization of growth hormone (GH), growth hormone receptor (GHR) and transforming growth factor b3 (TGF-b3) loci is available in breeder hens for Mazandaran native fowls breeding station, we studied their distribution in this population. A total of 156 blood samples were collected and a specific primer sets were used to amplify a fragment of GH, GHR and TGF-b3 loci using polymerase chain reaction (PCR). The PCR products from GH, GHR and TGF-b3 loci were digested with SacI, HindIII and BslI restriction endonuclease, respectively. In GH and GHR loci, allele A was the most frequent and ranged from 0.99 to 0.79 while, allele B was identified as a dominant allele at TGF-b3 locus due to the highest frequency (0.81). The frequency of BB homozygous genotype was the lowest (average = 0.03) whereas, AA genotype showed the highest frequency among all loci. The amplified fragment in GH locus was characterized by a deletion of approximately 118 bp. Deletion of 118 bp fragment not only reduced the expected size of the PCR product, but also, introduced a new restriction site for SacI enzyme at GH marker site. Further association analysis is required to clarify the effects of these marker genotypes on production traits in this breeder flock.

Key words: GH, GHR, TGF-b3, breeder hen