ANALYSIS OF HAPLOTYPE FREQUENCY DISTRIBUTION BY CSN2 AND CSN3 LOCUS IN THE CATTLE POPULATION OF THE UKRAINIAN BLACK-AND-WHITE DAIRY BREED

Abstract

The study of the genetic structure of the cow population of the Ukrainian Black-and-White dairy breed were carried out in loci of beta-casein (CSN2) and kappa-casein (CSN3) loci, and the distribution of haplotype frequencies was analyzed. The polymorphism of the experimental loci was determined using AS-PCR (allele-specific PCR) in the case of CSN2 and PCR-RFLP (restriction analysis) in the case of CSN3. The frequencies of genotypes and alleles, the value of observable (Ho) and expected (He) heterozygosity, the Wright fixation index (Fis) and the effective number of alleles (ne) were determined based on the results of the studies. Haplotype frequencies were determined by calculating the EM-algorithm using the EH+ program. Calculations of the standardized measure of deviation by linkage from the equilibrium state were made using the 2LD program. According to the results of the studies, polymorphism was revealed for both experimental loci in the cattle population of the Ukrainian Black-and-White dairy breed. At the CSN2 locus, the A1 allele frequency was 0.44; A2 – 0.56. At the CSN3 locus, the A allele frequency was 0.80; allele B – 0.20. The experimental cattle population was in a state of genetic equilibrium in accordance with both polymorphic loci. Based on the analysis of the haplotype frequencies distribution, haplotype CSN2A1-CSN3A was found to have the highest frequency (0,46), haplotype CSN2A2-CSN3B had the smallest (0,085). In the experimental cattle population of the Ukrainian Black-and-White dairy breed there is no deviation from the equilibrium state by linkage (D′ = 0.33; which is significantly less than the critical value) between the identified allelic variants of the CSN2 and CSN3 loci. This indicates that the distribution of haplotype frequencies is the result of the particularities of the corresponding alleles frequency distribution.