Ways of breeding of new generation of sires in Red-and- White breed

The purpose of the research was to analyze and substantiate the ways of breeding new generation of sires in Red-and-White breed. The materials of the article reveal theoretical approaches and practical implementation of breeding replacement bulls in breeding farms breeding Red-and-White breed. The criteria for equivalent evaluation of milk productivity traits by genetic value indices in the population of cows (Kd) and sires (B) both having evaluations for the quality of off spring and young ones were determined. Conditional selection differentials were determined and modeling of selection options for cows with different “blood-partness” of Holstein breed was carried out. The difference in the B and Kd values was positive values for milk yield of 460–1355 kg and negative by the mass fraction of fat 0.31–0.05 %. The milk yield coefficient was within the range of 7300–10 469 kg of milk, the milk mass fraction of fat coefficient was 3.95–4.71 %, and the milk mass fraction of protein coefficient was 3.18–3.79 %. The indices of the sires (B) selected for the “father of sires” group based on the same characteristics were: 8414–14 048 kg, 3.93–4.39 %, and 3.15–3.66 %, respectively. These parameters of milk productivity characteristics make it possible to breed a new generation of replacement bulls and successfully continue selection for their improvement. The cow longevity index and its average values for groups of daughters of individual sires were calculated for animal evaluation. A model of custom matings is proposed, and the breeding characteristics of the main and intermediate sires are given based on two variants of their evaluation. The replacement bulls will be the successors of the six previous genealogical complexes of the pedigrees of the sires of the “fathers of sires” group, which belong to the Holstein genealogical lines.