Relevance. The aim of the work is to study the effect of the biotechnological additive (dietary supplement) «Ares» in the cultivation of broiler chickens on their weight growth.Methodology. Scientific and production experience was carried out in the conditions of the poultry workshop of the educational and experimental farm of the Ural State Agrarian University on the poultry of the «Coob 500» cross. In all experiments, the control group›s poultry received a general household ration, the 1st experimental was given «Ares» additive in water in the amount of 150 g/t, the 2nd experimental was given «Ares» additive in feed in the amount of 300 g/t.Results. As a result of the research, it was found that all chickens (regardless of the group) increased their live weight with age, reaching 2632–2880 g by the end of cultivation, which meets the requirements of the cross standard. The highest live weight was obtained in the 2nd experimental group, where dietary supplements «Ares» were used in dry form in the amount of 300 g per 1 ton of compound feed. Absolute growth increases with age, which is most likely due to the increase in linear and volumetric sizes of chickens and their ability to increase feed intake. Over the entire growing period, their live weight increased 68.7, 67.2 and 73.8 times. The best indicators were in the group of chickens that additionally received 300 g/t of «Ares» dietary supplement feed. Starting from the 7th day, they had an excess of absolute growth indicators over chickens from other groups. The use of an additive in the form of a solution with a dose of 150 g per 1 ton of water showed a decrease in absolute growth over the entire growing period. The peculiarities of weight growth in broiler chickens receiving dietary supplements «Ares» were established, and the growth of broiler chickens itself followed the general biological patterns of growth and development.