Detection of Genetic Polymorphism in Growth Hormone Receptor Gene and Its Influence on Growth Traits in Kari and Balkhi Sheep

Variations in the growth hormone receptor (GHR) gene influence growth traits, which are important for economic selection in sheep breeding. This study aimed to investigate GHR gene sequence variations and their association with growth traits in two sheep breeds (Kari and Balkhi). A total of 150 animals per breed were included, and blood samples were collected. DNA was extracted using the NucleoSpin Blood Genomic DNA Purification Kit, and the gene was amplified through PCR with pre-designed primers. PCR products were sequenced using next-generation sequencing (NGS). Sequence analysis identified 620 variants, with 612 located in the intronic region. Five variants were found in the upstream region, and two synonymous variants were detected, along with one in the 3' UTR region. Correlation analysis showed that four SNPs (33,665,691 C>T, 33,668,886 T>A, 33,665,855 C>T and 33,667,058 C>T) in high-growth rate groups were positively correlated with weight gain, while four SNPs (33,662,328 G>A, 33,729,972 C>T, 33,753,532 A>G and 33,760,254 G>T) in low-growth rate groups were negatively correlated. These SNPs could serve as markers for marker-assisted selection to improve growth traits in local sheep breeds.