Polymorphism of CSN2 and TNF-α Genes in the Population of Holstein Cattle Bred in Ukraine

Peculiarities of the genetic structure of the population of Holstein cattle bred in Ukraine were studied by beta-casein and tumor necrosis factor alpha loci. Using the methods of allele-specific PCR (AS-PCR) and PCR with restriction fragment length polymorphism (PCR-RFLP) analysis, polymorphism of the beta-casein gene (CSN2) by allelic variants A¹ and A² and of the tumor necrosis factor-alpha (TNF-α) by SacI-polymorphism in the promoter region of the gene (–824 A>G marker mutation) and RsaI-polymorphism in the fourth exon were analyzed. It was proven that both loci are polymorphic in the studied cattle population. For each of the polymorphic loci, the main genetic and population parameters of the Holstein cow population were established. For the CSN2 locus, a significant predominance of the frequency of the A² allele over A¹ was established (0.78 vs. 0.22). For the SacI- and RsaI-polymorphisms of TNF-α, maximal (1.980 and 1.988) values of the locus polymorphism level (the number of effective alleles) were detected. For both mutations in the TNF-α gene, actual parity in the frequency values of the corresponding alleles was established (0.55 and 0.45 for the SacI-polymorphism; 0.54 and 0.46 for the RsaI-polymorphism). For the RsaI-polymorphism in the TNF-α fourth exon, a deviation from the state of genetic equilibrium according to Hardy–Weinberg was recorded in the studied population of animals, and a significant excess of heterozygous individuals was detected (25%). Based on the results of the analysis of milk productivity parameters of individuals with different CSN2 locus genotypes, it was established that individuals with the A²A² genotype are characterized by higher values of standard milk production as compared with individuals with the A¹A¹ genotype (p = 0.042). For the SacI- and RsaI-polymorphism of the TNF-α gene, there were no significant differences in the parameters of standard milk productivity for two lactations between individuals with different genotypes.