Accepted_test

Marker-assisted selection (MAS) has emerged as an effective method for improving agricultural production by exploiting the association of alleles with economically significant traits. Since the late 20th century, efforts have been devoted to identifying gene spectra related to potential physiological and positional DNA markers. Despite significant progress, questions persist regarding the universality of these associations across breeds. This study aimed to investigate the genetic structure of Kostroma cattle, analyzing SNP markers of candidate genes (GH, GHR, DGAT1, PRL, SCD, RORC, Lep, LepR, CSN3) and their associations with milk productivity traits. Genotyping was conducted on 75 bulls and 120 cows, followed by population genetic and associative analyses. Notably, no significant deviations from Hardy-Weinberg equilibrium were observed. Differentiation among samples was evident for CSN3, DGAT1, and LepR markers. The Wright's fixation index (F_ST) indicated 2.1% differentiation, with bulls exhibiting slightly greater variability. Analysis revealed significant associations between SNPs in bulls and milk productivity traits of daughters, particularly regarding the SCD and CSN3 genes. Furthermore, frequency characteristics of SNP alleles were determined, highlighting the potential for their use in selection, notwithstanding the lower frequency of the Lep (Y7F) allele in cows. These findings underscore the utility of incorporating genetic markers into traditional breeding practices for enhancing desired traits in Kostroma cattle. This research contributes to a deeper understanding of the genetic basis of milk productivity in cattle, providing valuable insights for future breeding strategies aimed at enhancing productivity and sustainability in livestock farming.