Dynamics of correlation coefficients of economic and productive characteristics depending on the age of cows

Abstract

In 2002, a new Ural type of black-and-white breed was officially registered. Animals of this type have high productivity indicators, but at the same time there is a decrease in the productive longevity of the breeding stock. The conjugacy of milk yield for lactation is established, which allows for the first lactation to carry out selection fory milk yield. The relationship of milk yield for the first lactation weakens with the age of the animals and becomes negative for the fifth lactation. The conjugacy of such characteristics as milk yield per lactation and fat mass fraction in milk varies both by lactation and relative to milk yield per lactation. The conjugacy between milk yield and protein in milk for lactation was negative with fluctuations from low to medium-negative. For 5 lactation, there is a high positive relationship between milk yield for the first lactation and protein mass fraction in milk for 5 lactation. There are fluctuations in the correlation coefficients for fat mass fraction in milk for lactations, the conjugation of the trait with each other remains positive in the period from the first to the 4 lactation, excluding the correlation coefficient of this indicator between 1 and 5 lactation.