REVIEW OF GENES VARIABILITY ASSOCIATED WITH MILK PRODUCTIVITY OF DAIRY CATTLE
The review analyzes publicly available literature data of associative studies that made it possible to identify and evaluate the influence of polymorphic gene variants on the performance indicators of dairy production. The data on the influence of polymorphic variants of the casein cluster genes, the LGB, DGAT1, SCD1, FASN, ABCG2, MGST1, LEP, PRL, GH1 genes and some transcription factors on the efficiency of qualitative and quantitative indicators of milk are presented. Single nucleotide substitutions and other polymorphic variants of the associated genes are given, as well as information about the proteins of the desired genes and their role in the animal during homeostasis and lactation. Phenotypic manifestations of significant substitutions in the studied genes and the nature of the influence of each polymorphic variant on the performance indicators of dairy production are described. According to the data of this review, it can be concluded that currently, to improve the productivity of cattle, it is necessary to resort to the technology of genotyping to increase the efficiency of positive selection according to the characteristics of milk production. Meanwhile, it should be noted that at present, the development of marker-assistant selection of dairy cattle is in crisis. Identified in associative studies, DNA markers do not provide for the most part a global improvement in the selection process. At the same time, the molecular mechanisms of formation of parameters of milk production remain poorly studied. It is necessary to carry out a systematic analysis of the molecular mechanisms for the formation of parameters of milk production, which will ensure an adequate selection of candidate genes for associative research and their further use in selection. In this case, one should use both bioinformational and experimental methods and approaches that are well proven in the field of medical genetics.