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.
Highlights
Provision of the population with full-fledged food products of animal origin, including milk and dairy products ‒ is the main necessity in ensuring the health of the nation and food security of any country [1-7]
The relationship of milk yield for the first lactation weakens with the age of the animals and becomes negative for the fifth lactation
The correlation coefficients of milk yield by lactation are presented in figure 1
Summary
Provision of the population with full-fledged food products of animal origin, including milk and dairy products ‒ is the main necessity in ensuring the health of the nation and food security of any country [1-7]. For the production of milk in the country in recent years, the country has used dairy cattle of domestic and foreign breeding, the main livestock of which is represented by black-and-white and Holstein breeds. These are related breeds whose origin comes from Dutch cattle. In the Sverdlovsk region, purebred bulls of the Holstein breed with high productive qualities according to their maternal ancestors were used on the breeding stock of the black-andwhite breed of the Ural offspring This made it possible to create an array of highly productive black-and-white dairy cattle, which in 2002 was officially registered as a new Ural type of black-and-white breed. The assessment of the relationship between the productive indicators of the Ural type cows, depending on their age, is relevant and has practical significance
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