An assessment of economically useful traits and external conformation of the Kazakh whiteheaded cows of the main genealogical lines, bred in the farms of the Altai Territory, was carried out. For the analysis, indicators of economically useful traits and conformation of first-calf heifers and full-aged cows of the Kazakh white-headed breed were used: live weight, measurements, total score for conformation, milk production. It was established that first-calf heifers of Zamok 3035 line surpass their herdmates in chest girth, and heifers of Zadorny 1325 and Korol 13682 lines are superior in oblique body length. Cows of Peon 29 line are inferior to their peers in live weight. The best indicators in live weight were noted in full-aged cows of Zadorny 1325 line, in milk yield – in Korol 13682 line. In general, there were no significant differences in most animal traits between the lines assessed. Analysis of full-aged cows belonging to the lines of Zamok 3035, Korol 13682, Zadorny 1325 showed that they surpass their herdmates in live weight, the lines of Korol 13682 – in milk yield. The study of the coefficients of heritability showed a low level of influence of the genotype on the variability of the main traits. This fact may indicate a high degree of consolidation of the Kazakh white-headed breed. In the breeding work with this breed, it is necessary to make wider use of sires belonging to the lines of Zadorny 1325, Zamok 3035. Particular attention should be paid to the rotation of genealogical groups. It is recommended to use new unrelated animals from other regions to increase the genetic variability of traits in herds. In order to do this, selection should be carried out in accordance with the grading requirements and selection parameters calculated for a particular farm.

The results of research on the creation of a breeding group of Hereford cows at the Novosibirsk Region breeding reproducer are presented. It was found that cows from the 3rd to 7th calves have the lowest coefficient of variability for live weight (from 1.9 to 2.7%), for milk yield - from 1.9 to 5.6%. The variation in height at hips (characterizing the manifestation of the type) was from 1.3-1.6%. Based on these indicators, a breeding group of 82 cows was selected and evaluated. The average live weight of the animals was 570.5 kg, which exceeds the standard of the breed by 50.5 kg or 9.7%, and corresponded to the elite-record class. The selection differential by live weight of cows of the whole herd and breeding group was 11 kg. Taking into account the coefficient of inheritance and the effect of selection on the first generation to achieve the indicators of the desirable type based on the cows of the breeding group will take 3.5 generations (10.5 years), respectively, for milk yield - 3.9 generations (4.5 years). More effective breeding achievement can be achieved in height at hips (1.1 generations and 3.3 years). Ten stud bulls selected for custom mating are homogeneous and rated elite-record class. They exceeded the breed standard by 151.5 kg (8.1%) in live weight at 3 years of age and by 115.3 kg (14.1%) at 5 years and older. They are characterized by a well-defined desirable type of constitution. Stud bulls obtained from the cross of the Canadian and Siberian selections with the complex index "B", according to the quality of progeny 104-105 recognized as improveers.

The results of studying the influence of the degree of kinship and genetic similarity of parental pairs on meat productivity of Hereford cattle are presented. An increase in homozygosity in herds of Hereford cattle in Siberia may reduce the effectiveness of breeding work. It was found that the selection of parental couples had a significant effect (p < 0.01–0.001) on the formation of offspring meat productivity. Cows from distant inbreeding and outbred (unrelated) parents were superior in live weight by 31–47 kg at the age of 3 and 5 years compared to closely related ones. The highest live weight ratios (16–66 kg) were observed in young animals obtained from outbred selection of parental couples compared to their peers obtained from closely related mating. Bullcalves from 8 to 15 months old, obtained from mating of unrelated parents, exceeded their peers from closely related mating by 105 g (14%), moderately related – by 87 g (11%) and distant by 69 g (9%). Low values of this indicator for the age-group of up to 18 months result from a large number of factors (genotype, maternal milk production, housing conditions) in the initial stage of organism formation. Bull-calves and heifers with an average degree of genetic similarity of parental couples at all ages had better live weight compared to their peers, due to heredity formed from both parents. A dispersion analysis of the data established a reliable effect (p <0.001) of the degree of genetic similarity of the parental pairs on the amount of live weight. The study of the degree of kinship and genetic similarity of parental pairs will allow to obtain the most accurate and reliable data on the breeding value of Hereford cattle of Siberian selection.