Proteins, like carbohydrates and lipids, are also essential nutrients. Without providing energy and complete protein, it is impossible to obtain complete products in the poultry industry. The experimental data of the researchers proved that not only the quantity, but also the ratio of the amount and amount of undetected proteins in the protein determines the biological value of the feed. It was shown that a chronic deficiency or lack of essential amino acids in the body leads to weight loss and ultimately to disorders. These indicators formed the basis for further research and laid the foundation for a more systematic study of the role of protein and amino acid nutrition in bird physiology. The role of individual amino acids in the life of the body was determined. It was found that a deficiency of methionine and cysteine causes a decrease in muscle tone, liver dystrophy, hemorrhage in the kidneys, weakness of the pelvic limbs. With a lack of lysine, deposition of subcutaneous fat decreases, dry skin appears, and hemoglobin synthesis decreases, the level of serum proteins, the absorption of feed nitrogen decreases. Increasing the concentration of lysine in the diet reduced the cysteine content and reduced the level of consumption. Chelated compounds of methionine and lysine have a positive effect on avian embryogenesis. Tryptophan deficiency is accompanied by clouding of the lens of the cornea. There is evidence that an increase in the concentration of linolenic acid and free tryptophan in the blood plasma of chickens depends on the amount of tryptophan in their diet. A lack of arginine or valine contributes to a violation of the functions of the nervous system in the form of a disorder of movement coordination, seizures. Valine, like glycine, affects the regeneration of hemoglobin. Hemoglobin level decreases with a lack of histidine. This is confirmed by the high content of this amino acid in the hemoglobin molecule. The absence, even temporary, of all amino acids is accompanied not only by loss of body weight, but also by muscle atrophy, hypoproteinemia and anemia; the body becomes more susceptible to infections and non-communicable diseases. A deficiency of amino acids leads to a decrease in hemoglobin, hematocrit, and the activity of certain enzymes. With an excess of a certain amino acid, the balance of the entire amino acid composition is disturbed. It can also cause impaired synthesis of another amino acid. So, antagonism is established between lysine and arginine, leucine and isoleucine, valine and leucine, tryptophan and threonine. Important is not only the number of individual or several amino acids, but also their entry in certain ratios. In the body during normal activity should be a continuous update of proteins. For different proteins, the update rate is different. So, 10% of blood plasma proteins are updated per day, about 50% of liver proteins - per week, and hemoglobin - in 28-30 days. Lack or absence in the diet of essential amino acids, the importance of which has also been established for the body, leads to a decrease in protein synthesis, an increase in the consumption of essential amino acids. The synthesis of essential amino acids in the body is carried out due to the products of the metabolism of carbohydrates, nitrogenous bases, carbolite and ammonium citrate. The ratio of non-essential amino acids also matters. So, nitrogen is used productively and is better absorbed by laying hens, if the ratio of essential amino acids to essential amino acids in feed diets is 1,0:0,8. The lack of proteins and amino acids in the body contributes to metabolic disorders, which affects not only the adult livestock of birds, but also young animals. As a result of metabolic disorders, the digestive system deteriorates, reproductive ability and resistance to infectious diseases decrease. Providing poultry with high-quality protein feed in industrial conditions, in which amino acids are contained in the required proportions, prevents economic damage, improves the quality of meat and egg products.