Breeding value and inheritance of signs of dairy productivity in crossed cows

Goal. To study the heritability of signs of dairy productivity of cows obtained from breeders of Holstein, Montbeliard, and Norwegian red breeds. Methods. The study was conducted during 2019–2024 using general scientific methods, including both empirical and theoretical approaches (theoretical analysis, hypothesis formulation), as well as special methods (genealogical, biometric, statistical, correlation analysis, determination of tribal value and its repeatability, inheritance). Biometric and statistical calculations were performed using the Statistica 13.0 computer program. Results. It was established that breeding bulls had the maximum influence on the value of genetic progress. Cows taken to the breeding core with low selection intensity have little effect on the genetic improvement of herds. The values of the coefficients of heredity of cow yield by 21.8–33.5% depended on hereditary factors and, accordingly, by 66.5–78.2% on paratypical ones. The qualitative composition of milk, namely: the content of fat in it and the total yield of milk fat, judging by the value of the coefficient of inheritance (from 0.312 ± 0.087 to 0.486 ± ± 0.113), was directly related to breed affiliation. Between the amount of milk yield and the content of the main components of milk (fat, protein, casein, dry matter, somatic cells), a significant negative relationship was established (from –0.37 ± 0.121 to –0.07 ± ± 0.037), which indicated a decrease in these signs for an increase in the level of milk yield. Conclusions. It was found that breeding bulls made the maximum contribution to the genetic improvement of the studied herds. Quantitative and qualitative signs of milk productivity had an average and high degree of inheritance, which gave reason to assert the possibility of effective selection on these productive signs.