Studies have been carried out to study the genetic structure of cattle populations of three breeds of beef productivity, grown in Volgograd region and the Republic of Kalmykia, based on the identification of polymorphic forms of the GH, MC4R and CAPN1 genes by the PCR-RFLP method. In total, 300 DNA samples obtained from animals of the Russian polled, Kazakh white-headed and Kalmyk breeds were analyzed. The article presents the optimal parameters of amplification and restriction reactions, as well as electrophoretic detection of restriction fragments. Based on the data obtained in the populations, the frequencies of alleles and genotypes were calculated, and the nature of the distribution of polymorphic variants of genes was described. As a result of associative analysis, a positive relationship between desirable genotypes and live weight was established. Taking into account the heterogeneity of the genetic architecture of the studied groups, the relationship of gene polymorphism with the productivity of animals in basic enterprises, it is recommended to conduct breeding selection in the direction of increasing homozygosity for the desired genotypes. Thus, according to the somatotropin gene, the VV genotype is desirable; for the melanocortin 4 receptor gene -GG; according to the calpain gene -SS. Using in breeding animals in which the desired genotypes were identified as a result of the studies performed, it is possible to improve the meat productivity of the offspring.