Application of protein, vitamin and mineral supplement in diets of 1-3 months old calves in rate of 5% per weight instead of a part of sunflower cake, containing rape, peas, lupin and vitamid on a basis of halites, phosphite, phosphate, sapropel and a mineral-vitamin preparation in structure of grain forage against winter rations on the basis of rich in herbs hay (5%), milk (68%), mixed fodder (20%), whole grain (7%), and also summer rations with grass and legume mixture (7%), hay (1%), milk (65%), mixed fodder (20%), integral grain (7%) makes it possible to receive daily average weight gain of calves at level 833-867 grams at expenses of forages for 1 centner of weight gain on 3,3-3,4 сentner of forage units. Introduction into rations of the protein, vitamin and mineral supplement on the basis of local protein and mineral raw materials in number of 10% per weight in structure of mixed fodder for calves at the age of 3-6 months old against the background of winter diets with haylage (28%), mixed fodder (64%), molasses (8%), as well as summer diets with grass and legume mixture (30%), mixed fodders (66%), molasses (4%) makes it possible to receive daily average weight gains of calves on 944-967grams at expenses of forages of 4,0-4,1 сentner of forage units. Feeding of 1-6 months old calves with mixed fodders with inclusion of 5-10% of protein, vitamin and mineral supplement per weight with grain high-protein crops against the background of winter and summer diets with a ratio of the deconjugate protein to the non deconjugate one - 65:35 (in control group - 71:29) instead of sunflower cake makes it possible to receive the daily average weight gain at the level of 900-927 grams at expenses of forages 3,7-3,8 сentner per forage unit. Cost of presented mixed fodders decreases on 14%, and the cost price per 1 centner gain - on 7-8%

Determination of the influence of new premixes on sperm quality and natural resistance of sire bulls during winter and summer periods was realized in the conditions of the republic of Belarus. Application of the developed vitamin and mineral additive in rations of sire bulls in course of winter and summer periods made it possible to increase their natural resistance, that was proved by the 7,2-8,8% increasing of the bactericidal activity of blood serum indicators, 0,6% increasing of lysozymic activity of blood serum, and 3,3-5,1% increasing of the phagocytic ability of leukocytes. There was determined the possibility to increase sire bull sperm quality during different year periods by means of application of the enhanced doses of vitamins and trace elements. As a result, the ejaculate volume increased on 7,4-2,4%, concentration of male germ cells in ejaculate on - 6,3-7,8%, sperm activity - on 6,7-7,3%, and also there was stated the decrease of spoilage percent of sperm production. Results of the industrial testing have confirmed efficiency of use of the recommended vitamin and mineral additive and calculated on its basis premixes. Its application made it possible to increase the quality of bull of sperm production on 3,6-10,8%

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.