Since 2021, Holstein breed of cattle is considered the main dairy breed in the Sverdlovsk region. The results of holsteinization cannot be underestimated, however, along with positive aspects certain problems were also identified such as a decrease in reproductive abilities, productive longevity, and an increase in the demand for feeding and housing. The purpose of the research was to study the age dynamics of milk productivity of cows of Holstein breed. It was found that a regular change in the lactation activity of cows with a change in age is traced, namely, an increase in milk yield until reaching mature lactation and then a slow decrease. Since the difference in milk yield was insignifi cant and unreliable, it can be concluded that milk yields stabilized up to and including the 7th lactation. An increase in the duration of lactation although it leads to an increase in milk yield per lactation reduces the efficiency of the industry due to losses from a decrease in the duration of the productive period and a shortage of calves per technological cycle, which is taken as the duration of the calendar year of 365 days. We have notedin terms of the mass fraction of fat in milk that regardless of age it exceeded the standard requirements. An increase in this indicator with age was noted. In terms of the mass fraction of protein in milk all animals up to and including the 9th lactation met the requirements of the breed standard. In terms of milk fat yield cows up to the 7th lactation met the requirements of the standard for Holstein breed and even slightly exceeded it. In terms of milk proteinyield cows of 1–3 lactations met the requirements of the standard. The rest except for cows of the 14th lactation had a lower level of this indicator and did not meet the requirements of the breed standard.
Kostomakhin et al. (Mon,) studied this question.