Studies were conducted to study the variability and correlation of indicators of dairy productivity of cattle in the conditions of breeding enterprises of the Omsk region, as well as the optimal size of the breeding group was determined on the basis of the Pareto diagram. It was found that the coefficient of variation of milk yield in cows of the red steppe breed was 23.4 %, which is 4.3% more than in cows of the black-and-white breed. To form breeding groups in breeding farms in the region, they must have a milk yield of at least 7000 kg of milk.