Association of the growth hormone c.2141C>G polymorphism with growth performance, slaughter traits, and meat quality in Kalmyk bull calves

Abstract

Background and Aim: The growth hormone (GH) gene is an important candidate locus for marker-assisted selection because its polymorphisms may influence growth, carcass characteristics, and beef quality. However, evidence linking the GH c.2141C>G polymorphism with meat productivity and physicochemical characteristics in Kalmyk cattle remains limited. This study aimed to evaluate the association of the GH c.2141C>G polymorphism with growth performance, slaughter traits, and beef quality in Kalmyk bull calves. Materials and Methods: Fifty Kalmyk bull calves were genotyped for the GH c.2141C>G polymorphism and classified as LL (n = 37) or LV (n = 13). Animals were monitored from 8 to 15 months of age under standardized feeding and housing conditions. Live weight and average daily gain were evaluated during the growth period. At 15 months, eight animals from each genotype-group were selected for slaughter and assessment of carcass characteristics and beef chemical composition. Genotype-associated differences were evaluated using appropriate statistical tests with correction for multiple comparisons, and Cohen’s d was used to assess effect magnitude. Results: LV bull calves had higher live weights than LL calves by 4.45, 20.5, and 25.9 kg at 8, 12, and 15 months, respectively, and their average daily gain was 5.1%–11.5% higher across the evaluated periods. However, these differences were not statistically significant (p > 0.05), although effect sizes indicated potentially relevant differences in growth performance. Significant genotype-associated differences were observed in slaughter and meat-quality traits. Carcass weight and internal fat weight showed large effect sizes (Cohen’s d = 2.28 and 3.53, respectively). Beef chemical composition also differed significantly between genotypes (p = 0.001–0.0013; Cohen’s d = 1.25–1.47). The LV genotype was associated with 1.01% higher protein and 0.23% higher ash contents, whereas the LL genotype was associated with 0.5% higher fat and 0.4% higher moisture contents. Conclusion: The GH c.2141C>G polymorphism was associated more strongly with slaughter characteristics and beef chemical composition than with growth performance in Kalmyk bull calves. The LV genotype showed favorable trends in growth and was associated with higher protein and ash contents, supporting further evaluation of this polymorphism as a potential marker for selection programs targeting meat productivity and quality. Larger populations are required to confirm its utility for marker-assisted selection. Keywords: beef cattle genetics, beef quality, carcass characteristics, growth hormone gene, growth performance, Kalmyk cattle, marker-assisted selection, meat productivity.