Determination of productivity and natural resistance indexes of laying hens after application of dry multienzyme preparation Vitazim (xylanase, 3600 units/g; cellulose, 3000 units/g; beta-glucanase, 7000 units/g); as well as the specification of optimal doses the enzyme were realized in the conditions of the Republic of Belarus. Research results showed that the best indexes of egg yields of laying hens were obtained after application in the main poultry diet of enzyme preparation Vitazim in dose 500 g/t that made it possible to increase the productivity in the experimemtal group on 12%. Application of Vitazim also promoted the increasing of natural resistance level of laying hens. There was stated the positive effect of Vitazim on bactericidal activity of blood serum. Before the beginning of test this index was the level of 44,35+/-0,92 – 56,52 +/-1,63. By the 300-th day of life the bactericidal activity of blood serum in experimental group administrated Vitazim in dose 300 g/t exceeded the control idexes on 3,8%; in the second experimental group (Vitazim in dose of 500 g/h) – on 29,5%; in the third experimental group (/vitazim on dose of 700 g/h) – on 23,7%.Vitazim administration also exercised positive influence on lysozyme activity in blood serum of lying hens

In the conditions of the Republic of Belarus there was analyzed the efficiency of application multi-enzyme preparations (drugs) Ehkozim (contained beta-glucanases; endo-xilanase; cellulose) and Vitazim (contained complex of enzymatic carbohydrases: xylanase; cellulose; beta-glucanases) in diets of lying hens. Vitazim was applied for destruction of complex structures: dietary fibre, protein, starch. Ehkozim was applied for albuminolysis of the main nonstarch polysaccharides of fodders. It was established that application of preparations in feeding of lying hens promoted the increasing of biological value of poultry meat, and prove to be economically expedient. Poultry meat of analyzed samples in accordance with physical, chemical and bacteriological indices, as well as in accordance with biological value and harmlessness was not worse than meat of control samples. As a result of the realized bacteriological research of all experimental samples of meat and internal organs there were not stated microorganisms Е. coli, S. aureus, bacteria of sort Proteus, B. сеreus and sulfate-reducing clostridium, salmonellas.

In the conditions of the Republic of Belarus there was determined the efficiency of application of different levels of vitamins and trace elements in feeding of servicing bulls. In course of the study there was analyzed the influence of different levels of supply of servicing bulls with vitamins A, D, E and trace elements (copper; zinc; manganese; iron; cobalt; selenium) on their reproductive ability. On the basis of the experiment there was calculated the economic efficiency of application of the developed vitamin and mineral additive. Research results showed that application of the developed protein and mineral additive in diets of servicing bulls in winter and summer periods made it possible to increase the ejaculate volume on 7,4% and 12,4% (P less than 0,05), sperm activity on 6,7 % (P less than 0,05) and 7,3% (P less than 0,01), concentration of spermium in ejaculate on 6,3% and 7,8% (P less than 0,05). Also, it promoted the lowering of percentage of defective sperm doses.

Development of new selenium preparations in a complex with vitamins for the purpose of decrease of trace element toxicity and increase of its bioavailability is the topical problem of veterinary science. A new antioxidant water-soluble complex Aesel, which includes selenium as the activated product of interaction of methionine and sodium selenite, vitamins A and E, is researched. Lethal doses of the preparation for mice and rats were identified through intragastric and subcutaneous introduction. Due to the results of the research it was determined that Aesel is rated among the forth class of danger, so it is dangerous to a very little degree. Lethal doses of the preparation on the pure selenium, calculated on Pershin method, for rats at parenteral introduction is equal 5,48, at enteral introduction - 39, for mice at parenteral introduction - 7,72 mg/kg. Lethal doses of the preparation calculated on all making components equal to 39000 mg/kg.