THE RELATIONSHIP OF PRODUCTIVE AND REPRODUCTIVE QUALITIES OF COWS OF THE LINE OF REFLECTION SOVERING ON LACTATION
In order to effectively carry out breeding work, it is necessary to take into account the correlation coefficients between economically useful traits in cows. The magnitude of the positive and negative correlation varies depending on the direction of selection, feeding conditions and keeping of animals. As a result of the conducted research, it was found that the majority of cows belonging to the Reflection Sovering line, namely 64.0% are young animals for the first and second lactation. Cows with full-age (third) lactation had the highest milk yield. Their milk yield was 8834 ±288.54 kg, which is 1555 kg or 21.4% more than that of the first heifers. There is a natural increase in milk yield from the first lactation to full-age, and then a gradual decrease until the end of the use of animals. The difference in the change in milk yield by lactation is unreliable. The average daily milk yields of cows at the end of lactation activity are quite high and range from 15.0 to 30 kg or more, which leads to an extension of lactation activity in order to obtain higher productivity indicators and ensure the efficiency of the industry. there is a direct relationship between milk yield for lactation and the duration of the service period. The correlation coefficients between these traits are from 0.49 to 0.85 in cows of the Reflection Sovering line, which indicates an average and high correlation of traits. For 7 lactation, the relationship had a negative indicator. There was also a certain positive correlation between milk yield for 305 days of lactation and the duration of the service period, but it was either very low and average for the third lactation, or high for the seventh. With a small number of cows of this age, their use has no practical significance.