Genetic Polymorphism of BoLA-DRB3.2 Locus in Ukrainian Cattle Breeds

The results of the study of BoLA-DRB3 gene polymorphism in four domestic breeds are presented: Ukrainian black-and-white dairy (n = 293), Ukrainian red-and-white dairy (n = 131), Gray Ukrainian (n = 93), and Ukrainian white-headed (n = 49). The allele frequencies were determined based on the analysis of restriction fragment length polymorphism of the products of amplification of BoLA-DRB3 gene exon 2. Genetic profiles of the breeds were formed according to the following indices: allele (Pₐ) and genotype (Gₐ) frequencies, observed (Hₒ) and expected (Hₑ) heterozygosity, Wright fixation index (FIS), total (Nₐ) and effective (Aₑ) number of alleles, and Shannon (I) and Pielou (J) efficiency indices. The maximal number of alleles were in the experimental sample of Ukrainian black-and-white dairy breed (Nₐ = 37). In Ukrainian red-and-white dairy, Ukrainian white-headed, and Gray Ukrainian breeds, 31, 29, and 28 variants were found, respectively. In two breeds, the alleles with “no established nomenclature” were typed: Gray Ukrainian, jba, *jab, *jbb, *nad and *nda; Ukrainian white-headed, *nab, *mdb, *iab, *gbb, *fbd, *naa; their portion was 8.9 and 7.1%, respectively. The portion of “informative” alleles was: Ukrainian black-and-white dairy, 55.8% (seven alleles); Ukrainian red-and-white dairy, 60.4% (six); Gray Ukrainian, 69.9% (four); Ukrainian white-headed, 65.3% (seven). The expected heterozygosity and Wright index had the following values: Ukrainian black-and-white dairy, Hₑ = 0.942, FIS = 0.022; Ukrainian red-and-white dairy, Hₑ = 0.93, FIS = 0.032; Gray Ukrainian, Hₑ = 0.774, FIS = 0.041; Ukrainian white-headed, Hₑ = 0.927, FIS = –0.035. According to biodiversity indices, the greatest variability is typical for the Ukrainian black-and-white dairy breed (Aₑ = 17.2; I = 3.13; J = 0.6). The Ukrainian white-headed (Aₑ = 13.7; I = 2.93; J = 0.61) and Ukrainian red-and-white dairy (Aₑ = 11.5; I = 2.87; J = 0.558) cattle also had a high level of variability. A low level of biodiversity was found in Gray Ukrainian breed (Aₑ = 4.42; I = 2.21; J = 0.455). The analysis of BoLA-DRB3 gene exon 2 polymorphism demonstrated that the greatest genetic diversity is typical for the Ukrainian black-and-while dairy breed. According to genetic distances, the domestic breeds are combined in a single cluster with Holsteins, which indicates their genetic relationship.