The Comparison of CSN2 (rs43703011) Beta-Casein Gene Options Frequencies in Different Breeds of Ukraine Cows and the Prospect of Creating Herds with the A2/А2 Genotype

Abstract Using real-time polymerase chain reaction methods, we have researched the CSN2 polymorphism (GenBank M55158; SNP rs43703011) gene in 4 breeds of cows in the North-East of Ukraine. The observed distributions of genotype frequencies А1/А1, А1/А2, А2/А2 and A1 or A2 alleles varies considerably in different cattle breeds: Lebedyn cattle - 14.6%, 31.7%, 53.7% (0.3 and 0.7); Ukrainian brown dairy breed - 6.8%, 43.2%, 50% (0.28 та 0.72); Simmental cattle - 7.3%, 51.2%, 41.5% (0.33 and 0.67); Ukrainian black speckled milky – 38.5%, 34.6%, 26.9% (0.56 та 0.44). The ratio of genotypes and alleles were found significant differences when comparing Lebedyn cattle and Simmental cattle (р=0.01), Lebedyn cattle and Ukrainian black speckled milky (р<0.0001), Lebedyn cattle compared to all other breeds (р=0.04), Ukrainian brown dairy breed and Ukrainian black speckled milky (р<0.0001), Ukrainian brown dairy breed compared to all other Ukrainian breeds (р=0.008); Simmental cattle and Ukrainian black speckled milky (р<0.0001), Simmental cattle (р=0.002) and Ukrainian black speckled milky (р<0.0001) to all other breeds. The obtained results indicate the prospects of breeding work to create herds with genotype A2/A2 animals - specifically with the Lebedyn cattle.