Abstract
The article presents research materials on the adaptive and productive qualities of the third-generation heifers of Aberdeen Angus cattle in the conditions of the "Zholdasbay-agro" farming enterprise of the North Kazakhstan region. The object of study was the growth and development of third-generation heifers obtained by Canadian and European selection of the Aberdeen-Angus breed. According to the results of the study and the summary of clinical signs, the frequency of antenatal hypotrophy in newborn calves of the Aberdeen-Angus breed of Canadian selection was 12.3%, European 8.7%. The research results showed that the relative growth rate in European calves up to 6 months is higher than in peers of Canadian breeding, but in the period from 6 to 8 months, calves obtained from cows of the second generation of Canadian breeding are superior to calves of European selection. The established tendency of a lower growth rate of heifers obtained from cows of Canadian breeding may be associated with an increase in the tension of regulatory mechanisms that ensure the adaptation of animals to new environmental conditions.