BREEDING VALUE AND PRODUCTIVITY OF COWS DEPENDING ON THE LEVEL OF HOLSTEINIZATION IN THE STEPPE ZONE OF THE REPUBLIC OF NORTH OSSETIA-ALANIA

As a result of the absorption crossing of domestic cattle breeds with the best European breeds, a large array of animals with different bloodlines in improving breeds was formed. However the breeding and productive value of crossbreeds, depending on the genotype, is ambiguous. Therefore in the conditions of the ACS Mozdok district of the Republic of North Ossetia-Alania, a comparative analysis of the productivity of black-and-white cows with different proportions of Holstein blood was carried out. Using breeding and primary accounting data from 2010 to 2023, groups of cows were formed: the first with a share of Holstein blood of 50 % or less, the second - 51-75 %, the third 76-87.5 %, the fourth - 87.6 % or more. The results of the comprehensive assessment showed that Holsteinization improved the breeding qualities of the herd animals as a whole, with the highest breeding value being demonstrated by cows with a bloodline of 76-87.5 % and 51-75 %. In terms of the ratio of elite and class animals the advantage was noted in the second group with a Holsteinization level of 51-75 %. The analysis of the productivity and longevity of the animals showed that the highest milk yields were observed in cows in the groups with a bloodline of 51-75% and 76-87.5 %, and lower yields were observed in the groups of low- and high-blooded animals. The highest productivity indicators were demonstrated by cows with a Holstein bloodline of 51-75 %, and the superiority, compared to groups 1, 3 and 4, was as follows: milk yield: 943.1; 398.8 and 796.6 kg, and milk fat yield: 44.5; 20.2 and 39.6 kg, milk protein: 35.8; 15.7 and 29.4 kg. In all cases, the difference was reliable (P>0.999 and P>0.99). Cows with the share of improving breed blood of 76-87.5 %, although inferior to the animals of group 2, also reliably (P>0.99) surpassed the others both in productivity and in the duration of use. The difference, compared to the first (50 % and < ) and the fourth (87.6 and >), was in milk yield: 544.3 and 597.8 kg, the amount of milk fat: 24.3 and 19.4 kg, protein: 20.1 and 13.7 kg, longevity: 0.2 and 0.4 lactations, lifetime productivity: 2960 and 3216 kg.