The effect of LGB gene polymorphism on milk productivity indicators of Kholmogorsky cows

In modern breeding work, considerable attention is paid to genetic resources of cattle, genetic assessment of which, with proper crossbreeding and selection, can increase efficiency of the entire industry. One way to realize the genetic resources of animals is to use information about polymorphism of milk productivity genes. The aim of the study was to determine polymorphism of β-lactoglobulin gene in in Kholmogorsky cows and to identify its effect on economically valuable milk indicators. The experiments were carried out on the breeding stock of Kholmogorsky breed in “Kholmogorsky Plemzavod”. The genotype of the studied animals for LGB gene was determined by PCR RFLP using Hae III restriction endonuclease. It was established that the allele B of the β-lactoglobulin gene was dominant in the genome of the studied sample of cows and its frequency of occurrence was 68%, while the most common genotype was AB (47.4%). To assess the effect of different LGB genotypes on milk productivity and milk quality of Kholmogorsky cows, productivity indicators for the last completed lactation were combined into subgroups depending on the genotypes and compared with each other. Most likely, the uniqueness of the Kholmogorsky breed, expressed not only in terms of milk productivity, exterior and constitution, but also in the gene pool, influenced the discrepancy between the obtained results and general patterns. Firstly, in our case, B allele has a positive effect both on qualitative and technological characteristics of milk, and on quantitative indicators of milk productivity. Secondly, the largest value of milk yield and the mass fraction of dry matter belongs to animals with the AB genotype. We recommended to include the procedure for assessing polymorphism of LGB gene in a set of breeding and production work activities to increase the economic efficiency of the enterprise. Such a step will also contribute to the further comprehensive study of this gene as a breeding marker.