Рroteins and amino acids as the basis of nutrition in animal husbandry

Protein is considered a key nutrient in the ruminants diet. It provides not only the animal with amino acids, but also nitrogen (N) for microbial protein synthesis. The article studied the effect of a mixture of essential amino acids lysine-methionine-threonine-tryptophan on the digestibility of substances and the growth of calves from 9 to 18 months of age. The components of the diet (per 1 kg of feed) were used: I experimental group – 2 g of lysine+2 g of methionine+3 g of threonine+1 g of tryptophan, II experimental group – 3 g of lysine+3 g of methionine+4 g of threonine+2 g of tryptophan. The inclusion of a mixture of amino acids in the II experimental group was accompanied by an increase in live weight by 11.7 % (p<0.05) due to better use of bacterial nitrogen by 8.3 % (p<0.05), amino acids in the duodenum – by 3.46% (p<0.05) than in the I experimental group and by 8.83 % (p<0.05) than in the control group. The growth rate of the tissues and their protein composition changed with the growth of the animals. There are the content of amino acids in some tissues of the calves body. It can be noted that the amino acid composition of many organs and tissues of the calves body changes in the direction of increase in the first days of life compared to newborns, and in the bones, on the contrary, there is a decrease in their amino acid composition due to age. Thus, the positive effect of a mixture of amino acids in the ratio of 3 g of lysine+3 g of methionine+4 g of threonine+2 g of tryptophan provided an increase in the processes of protein biosynthesis in muscle tissue.