Cattle milk urea as a marker of technological properties and balanced feeding diet (review)

The purpose of the study is to summarize scientific data on the relationship between the level of urea and protein in cattle milk as a way to control the diet in terms of energy-protein ratio. A review of research papers over the past 10 years is presented on the analysis of the ratio of urea and the mass fraction of milk protein in cows, the relationship between changes in the urea index and a decrease in reproductive function in cows, the level of somatic cells and urea values, as well as the dependence of the urea index of milk on the method of housing and milking. The studies were carried out on cows of the Ayrshire, Holstein, Black-and-White and Kholmogory breeds. Determining the content of the mass fraction of protein and urea on farms in real time makes it possible to identify an imbalance in the diet of cows in terms of energy- protein ratio. Inadequate feeding of cows is a predisposing factor to the occurrence of diseases in animals; against the background of metabolic disorders and a decrease in the immune response, the animal deve- lops reproductive dysfunction, and the period of economic use of cows is reduced. An increase in the level of urea in milk indicates the insufficient efficiency of using crude protein in the diet for highly productive cows, as a result of which the resistance of the animal’s body decreases and vulnerability to pathogenic and opportunistic microflora increases. A decrease in the level of urea in milk leads to a decrease in the reproductive function and productivity of cows. The urea index, like other quality indicators of milk, may vary depending on age, clinical and physiological condition, lactation period and the level of milk yield of cows of various dairy breeds. Timely adjustment of animal feeding rations makes it possible to maintain their health, productivity, reproduction, improve the quality of milk and reduce the economic costs of overfeeding animals with proteins.