The relationship of economically useful features of Holstein cows with different combinations of selection

The study of the relationship between economically useful features of Holstein cows with different combinations of selection is an urgent task of dairy cattle breeding. The article provides data on the analysis of the correlation between indicators of dairy productivity. The correlation of milk yield over 305 days of lactation and the mass fraction of fat in milk, the mass fraction of protein in milk, and body weight was studied. A positive correlation was found between milk yield and fat content in milk (correlation coefficients: 0.21; 0.49; 0.09) for animals belonging to the control, first and second groups. In animals of the first, second and fourth groups, a weak positive relationship was found between milk productivity and protein levels in milk (r = 0.09; r = 0.10; r = 0.01). For all groups of animals studied, there is a negative relationship between fat content and protein content in milk, as well as between total milk yield during lactation (305 days) and the live weight of the animal. A negative relationship was found between the percentage of protein and the live weight of the first heifers in cows of the first, second and third groups, while in the remaining groups this relationship is positive.