Аннотация
The results of a study on testing Kazakh white-headed bull calves according to their own productivity are presented. The age dynamics of live weight, average daily gain, measurements and body indexes, feed costs per 1 kg of live weight gain, meat forms at the age of 12 and 15 months, indicators of class and index estimates of breeding value of bull calves, some breeding and genetic parameters of the most important signs of breeding and productive qualities of animals were studied. The average live weight of Kazakh white-headed bull calves tested for their own productivity at the age of 8 months was 229.97 kg, which exceeds the requirements of the breed standard by 20 kg, and indicates high milk production of cows and good feeding conditions for bull calves after weaning. The live weight of bull calves at the age of 12 months exceeds the breed standard by 13.9 kg, at the age of 15 months – by 35.6 kg. The highest coefficient of variation in body weight was observed at the age of 8 months (Cv=7.68) compared with 12 months (Cv=5.66) and 15 months (Cv=3.16). The highest average daily increase in body weight was observed in the period of 12-15 months (942.28 g.), the lowest value was established in the period of 8-12 months (699.43 g.). For the entire test period from 8 to 15 months of age, the average daily increase in body weight was 812.48 g. In the period from 12 to 15 months of age, the highest value of the coefficient of variability was 11.26, which to a certain extent makes it possible to select bull calves for breeding purposes most reliably. Feed costs per 1 kg. The average increase in the group from 8 to 12 months of age was 9.72 feed units, from 8 to 15 months of age, respectively, 9.29 feed units. For the period from 8 to 12 months of age, the number of steers that received the Elite complex class for breeding value was 3.4%, Class 1 – 34.5% and class 2 – 62.1%, while 17.2% of bulls received a breeding index over "100" during this period, and 82.8% received a breeding index up to "100". During the period from 8 to 15 months of age, the number of bulls with the elite–record complex class was 7.0%, the elite class was 58.6%, and the 1st class was 3.4%, while the number of bulls with a complex breeding index above "100" was 10.3%, and up to "100" was 89.7%.