Association of Growth Hormone Gene Polymorphisms (A1795>T and T1749>C) with Productive Performance and Egg Quality in Iraqi Indigenous Chickens

Abstract

The Growth Hormone (GH) gene is a pivotal candidate marker for improving production traits in poultry due to its essential role in growth, metabolism, and reproduction. This study aimed to investigate the associations between two specific Single Nucleotide Polymorphisms (SNPs) in the GH gene (A1795>T and T1749>C) and the productive and physiological performance, as well as the metabolic status of Iraqi indigenous chicken. A total of 100 local hens were genotyped using PCR method amplification followed by Sanger sequencing. Productive traits included body weight at sexual maturity, egg production rate, egg mass, and feed conversion ratio (FCR), in addition to physiological indicators. Results sequence analysis revealed highly (P≤0.01) significant genetic variations. The A1795>T polymorphism was significantly (P≤0.05) associated with egg weight, certain egg quality traits, and FCR, with the AT genotype showing superior performance in these parameters. Furthermore, the T1749>C polymorphism exhibited a significant (P≤0.05) to highly significant (P≤0.01) effect on egg weight, egg production, egg mass, and FCR. Conversely, some other traits showed no significant differences, (P≤0.05) suggesting a neutral genetic role for these markers in specific production aspects. These findings indicate that the A1795>T and T1749>C SNPs in the GH gene can serve as effective molecular markers in Marker-Assisted Selection (MAS) programs to enhance the genetic potential of Iraqi indigenous poultry while maintaining their environmental adaptation.