Relevance. The main factors having a significant impact on the growth and development of young animals, and its further productive indicators are heredity and environmental impact [6, 7, 10].

At the present stage, it is important to realize the high genetic potential of animals with a different proportion of genes of the Holstein breed. For successful solution of the issue, along with the improvement of feeding and keeping conditions, it is necessary to provide a scientific substantiation of the degree of influence of genetic factors on the formation and implementation of the productive qualities of an animal of a new type [3, 8, 11].

Genes are carriers of heredity, and their totality determines the genotype of the animal. Throughout the life of an individual, the genotype remains unchanged and affects the development of all properties and characteristics of the organism [1, 12].

Currently, there is an extensive distribution of crossbred animals with varying degrees of blood in the Holstein breed and the lack of methods for determining the optimal genotype for breeding animals in “oneself” [5, 9]. Therefore, in the breeding of dairy cattle, the main attention is focused on the improvement of methods for determining the genetic potential of crossbred Holstein animals for obtaining highly productive individuals, which is quite relevant [2, 4].

The purpose of the researches was to determine the optimal variant of using the seed of servicing bulls of the Holstein breed of the Reflection Sovering 198998 line in the conditions of ART OAO in the Pravoberezhny District of the North Ossetia-Alania. For this purpose, we studied the growth rate of the crossbred young stock of the Black-and-White breed with a blood relationship of 1/2, 5/8 and 3/4 to the Holstein breed.

Materials and Methods. For the research, 3 experimental groups were formed from clinically healthy young animals, taking into account age, live weight, and the productivity of their ancestors. Each group included 10 heifers with a percentage of blood in the Black-and-White Holstein breed from 50 to 75 %: 1-st group – 1/2-thoroughbred, 2-nd group – 5/8-thoroughbred and 3-rd group – 3/4-thoroughbred.