Allelic frequency of beta-lactoglobulin gene in different cattle breeds

The results of research on the frequency of genotypes AA, AB, BB and alleles A and B of milk protein beta-lactoglobulin in various cattle breeds over the past decades were presented and summarized. The livestock of the following foreign countries was considered: Italy, India and the Czech Republic. Also, on the territory of the Russian Federation, breeding stock and sires of the Republic of Bashkortostan, Tatarstan, Pskov, Samara and Arkhangelsk regions, as well as sires in the Altai Territory, were studied. Black-and-­White breed is the most studied one. Moreover, there are data on the Simmental and Kholmogory breeds of cattle. The frequency of allele B among the breeding stock of Black-and-­White breed in farms ranged from 0.21 to 0.64. The frequency of allele B among the breeding stock of Simmental breed in farms ranged from 0.42 to 0.65. The frequency of allele B among the breeding stock of Kholmogory breed in farms was from 0.60 to 0.70. The frequency of allele B among sires of Black-and-­White breed ranged from 0.43 to 0.69. In most farms, BB genotype leads in terms of quality indicators of milk productivity, and AB genotype leads in quantitative indicators of milk productivity. However, in some farms, AA genotype prevails in terms of milk yield and protein, and this genotype is also associated with a high content of dry skimmed milk residue and resistance to mastitis. Thus, further in-depth study of the beta-lactoglobulin gene is necessary, since new data will expand the understanding of the effect of this gene on economically useful traits of animals and will eliminate contradictions in the available data.