Polymorphisms in the GH gene and their influence on milk production traits in local buffaloes

Abstract

This study was conducted in a private sector buffalo farm in Al-Qurna, located north of Basra Governorate, between December 2023 and November 2024. It covered the summer (July and August 2024), autumn (October and November 2024), and winter (December 2023, January and February 2024) seasons. The purpose of the experiment was to examine the impact of the mid-lactation stage on genetic polymorphism in the growth hormone (GH) gene members (E4, E5, E6, E8) in the blood of buffaloes, and their relationship with serum GH levels during mid-lactation. Thirty blood samples were collected from the same buffaloes (n=30). Polymerase Chain Reaction (PCR) was used to amplify the targeted genes, and nucleotide sequence analysis was performed to detect polymorphisms. The results were compared with GH gene genotypes in the GenBank database. Two genotypes of the GH gene were identified in the mid-lactation buffaloes. DNA sequencing of the GH genes (E4, E5, E6, E8) was carried out, and the sequence data were compared with two references from the NCBI database. The E4 gene showed no differences when compared with Acc. NC_059175, but several mutations were observed compared with Acc. HG738860. The E5 gene sequence revealed polymorphisms when compared with both Acc. KC107765 and Acc. NC_059175 references. Although the E6 gene sequence showed no polymorphisms, the E8 gene sequence displayed a single-point mutation. Additionally, the results indicated significantly higher (P≤0.05) serum growth hormone levels in genotype A compared to genotype B.