Association of two missense mutations in the MSS51 and KAT6B genes with body weight at different ages in cows of the Yaroslavl breed

The Yaroslavl cattle is a native Russian dairy breed developed in the 19th century from the Northern Great Russian cattle, which were adapted to withstand harsh climates and poor forage conditions. Previous studies identified two breed-specific missense mutations in the MSS51 (Ala415Glu) and KAT6B (Val105Met) genes that negatively impact the body weight of the animals. This study aimed to confirm the association of these missense mutations in the MSS51 and KAT6B genes, along with the mutant haplotype containing both mutations, with live weight at various ages in the Yaroslavl breed using an expanded sample set. We genotyped 113 cows for these missense variants and analyzed their associations with live weight at birth, as well as at 6, 10, 12, 15, and 18 months in a combined sample of 143 animals, which includes earlier data. We employed linear regression and one-way ANOVA for statistical analysis. The results from linear regression indicated significant associations with live weight at 6, 12, and 18 months for the mutation in the KAT6B gene. The MSS51 gene mutation was associated with live weight at 6, 12, 15, and 18 months. Notably, the mutant haplotype was linked to live weight across all ages from 6 to 18 months. One-way ANOVA revealed significant associations of live weight with KAT6B genotypes only at 6 months. For the MSS51 gene mutation and the mutant haplotype, significant associations were found at 6, 12, 15, and 18 months. In both statistical tests, the most significant association was observed for the mutant haplotype rather than for the individual variants. These findings could be instrumental in enhancing the live weight of beef hybrids utilising the Yaroslavl cattle breed.