The nature of the relationship between milk yield and milk components

With the increase in milk yield of cows, the correlation between milk yield and the content of fat and protein in milk changes significantly. A positive relationship between milk yield and fat, milk yield and protein are maintained in the group of cows with a milk yield of 5,000 to 6,000 kg of milk, and as the milk yield increases, the correlation decreases. With the increase in milk yield, the fat content in milk decreased from 4.05 to 3.88 %, the decrease was 0.17 %, while the protein content decreased by 0.25 % from 3.54 to 3.29 %. With the increase in milk yield, the protein content in milk decreases more intensively compared to fat. Targeted selection of cows for fat contributes to an increase in protein in milk and selection of cows for protein will increase the relationship between the fat and protein content in milk. In practice, cows with high protein content but not high productivity indicators are often encountered. In our studies, 20 % of individuals have a combination of milk yield and milk protein content at a high level. The correlation in this case between fat and protein is positive with an average degree of reliability (P>0.99).