The results of the monitoring of heavy metal contamination of components of the technological system "Soil – water – feed – production" in the conditions of poultry farms of Odessa region are presented in the dissertation, as well as theoretical and experimental substantiation of the use of sodium selenite and phytochemical supplements «Phytohol» and «Phytopank» to laying hens to increase the natural resistance, productivity and quality of their products. According to the results of laboratory studies, the average content of heavy metals in the soil of farms in the Odessa region, where cereals are grown for feeding poultry, was lower than the MPC. However, due to the summation effect (accumulation factor K = 1.12), the overall risk of heavy metals being combined is relatively high, requiring the development of appropriate precautions. In the poultry farms studied, the content of heavy metals was lower than the MPC in the feed and water for laying hens. However, despite the low level of contamination of feed and water with heavy metals, their content in the body of hens, as well as in eggs and litter was high. Thus, Cuprum content was 30.0% higher in the heart, 60.0% in eggs, 166.0% in blood, and Zinc content in litter was 22.0%. In comparison with the separate use, the complex use of phytochemical supplements «Phytohol» and «Phytopank» and sodium selenite proved to be the most effective in reducing the content of heavy metals in the body and eggs of hens. The use of sodium selenite, «Phytochol» and «Phytopank» supplements to laying hens in the period of active oviposition stimulated the state of natural resistance of the organism, as evidenced by the increase in hemoglobin and erythrocyte content in the blood, as well as higher rates of LASK and LAS. The use of sodium selenite and phytochemical supplements «Phytohol» and «Phytopank» contributed to a higher level of physiological processes in the body, which is confirmed by a significant increase in the serum content of total protein, non organic phosphorus and glucose, the activity of enzymes Aspartate and Alanine and the alkaline phosphatase. The physiological state of the body of the laying hens under the influence of sodium selenite and phytochemical supplements contributed to a higher live weight, significantly more mass of carcasses. The use of sodium selenite and phytochemical supplements to laying hens contributed to higher egg productivity, namely the egg production, egg mass, including egg yolk and shell. Combined use of feed additives of sodium selenite and «Phytohol» and «Phytopank» to laying hens is cost-effective, which is confirmed by the cost-effectiveness calculation, which was 2.30 UAH per 1.0 UAH of costs.
