SUMMARY
Selenium is a biologically active microelement, contained in a number of hormones and enzymes. In a bird or animal organism selenium performs the following functions: strengthens the immune system, stimulates formation of antibodies, macrophages and interferons. Also, it is a powerful antioxidant agent. It stimulates processes of metabolism in the organism, protects the organism against toxic manifestations of cadmium, lead, thalium and silver; stimulates reproductive function, decreases acute development of inflammatory processes; stabilizes functioning of the nervous system; normalizes functioning of the endocrine system. Furthermore, it stimulates synthesis of hemoglobin, takes part in secretion of erythrocutes, neutralizes toxins, prevents and stops development of malignant tumors. It also has a positive effect on the cardiovascular system of an animal organism: prevents myocardosis and decreases the risk of development of cardiovascular diseases. Deficiency of selenium in the organism causes (depending upon the extent of deficiency) either physiological changes within the regulatory norm, significant disorders of the metabolism, or specific diseases. Around 75 different diseases and symptoms of pain are related to selenium deficiency. In most countries, the level of selenium consumption remains low (20–40 µg/day). There are several ways of improving of the selenium consumption of a population: consumption of selenium as a medication or dietary supplement, producing selenium-enriched bread, growing greens and vegetables rich in selenium, producing selenium-enriched beverages, products of animal origin, which would be rich in selenium. In the scientific-agricultural sphere studies have been made on the influence of adding different doses (0.2–0.6 mg/kg) of selenium in mixed feeds and peculiarities of its depositing and distribution in the muscle tissues of young growth of different species of poultry. It has been found that feeding broiler chickens, baby geese and ducklings with mixed feeds containing selenium in studied doses contributed to a reliable increase in concentration of this microelement in the chest muscles respectively by 21.7–106.7%, 35.1–40.0% and 23.2–66.0% and the leg muscles – by 13.0–85.7%, 57.4–61.7% and 20.5–79.4%. The meat of these types of birds is safe for human consumption from the perspective of food hygiene, for its selenium content is not higher than the TLV of this microelement for meat products (1.0 mg/kg). Consuming selenium-enriched meat of chickens, baby geese and ducklings within recommended physiological norms (115 g of meat products/day) satisfies the daily need of an adult for this microelement (70 µg) y 12.0–23.5%, 29.1–30.6% and 11.3–21.5% respectively. Taking this into account, selenium-enriched bird meat can be considered a dietary foodstuff suitable for biocorrectional function in humans. The viability of enriching bird meat products with selenium by adding selenium-containing premixes to fodder was proven experimentally. It was proven that adding optimum doses of selenium to mixed feeds for young birds bred for meat has a positive effect on the quality of meat, particularly on its biological value.