The efficiency of influence of iodon on the reproductive function of fullmouthed sire bulls of white-and-black breed was studied in the conditions of the Republic of Belarus. There were formed two groups of sire bulls: experimental group with low indices of sperm quality; control one – with high indices. In course of studying the interrelation of thyroid and sexual glands there was established the presence of parallelism in their development and function. In a period of sexual arousal the thyroid gland came into hyperactivity condition. At the same time, the quantity of triiodothyronine increased from 2,23 +/-0,02 to 3,05 +/-0,02 ng/ml, thyroxine - from 38,7 +/-1,02 to 59,8 +/-1,07 ng/ml. For the increasing of the reproductive qualities of sire bulls there was developed a iodine-containing preparation Iodon which should be spread with a medical syringe over a skin along the spine column. Iodon preparation applied in such a way made it possible to reduce the stressful influence more efficiently in comparison with an injection; it was well acquired and promoted the increasing of the reproductive function of sire bulls. The Iodon was developed on a basis of dimethylsulfoxide that promoted the efficient absorption through a skin. The preparation is a homogeneous hyaloid russet liquid with a specific smell, it is produced in bottles of 200 and 400 cm cubic. Iodon preparation realizes medical and preventive action in cases of impairment of sexual glands function against the background of iodine hunger. The preparation does not possess any allergenic properties, shows weak cumulative properties, and is harmless. The sperm quality improvement has been marked in all parameters, sexual reflexes become more stable and vigorous, animal fertility increased

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%

Balanced complete feeding proved to be one of the major conditions of animal productivity increase and improvement of their reproductive qualities. Full value of feeding could be obtained at the expense of forage quality improvement and perfection of structure of the rations providing the increasing of metabolic energy use by breeding bull-calves. Analysis of the efficiency of metabolic energy use by the replacement bull calves under conditions of various sugar and protein ratio was realized in the Republic of Belarus. Research results showed that enrichment of replacement bull calves (with 325-405 kg of live weight) rations with easy digestible carbohydrates (sugar and starch) in ratio of 32% from a dry matter ration, including 15% of stable starch made it possible to increase the transformation of metabolic energy into energy of body weight gain on 21,73 - 23,96 MJ or on 10,3%, that as a result correspondingly increased the daily average weight gains on 7,9% and reduced the expenses for forage energy for 7,1% counting on an energy unit. According to the ejaculate volume indices the bull calves of the second experimental group surpassed analogues of a control group on 14,8%, and according to sperm concentration indices - on 12%. The average quantity of the frozen doses of sperm has made 65%

Research was directed towards selection of national, accessible and cheap ingredients of whole milk replacers in the conditions of the Republic of Belarus. The efficiency of compounding preparation and its use in calves feeding at an early age was analysed. There was developed the technological scheme of application of hydrodynamic installation which operates according cavitating principle and makes it possible to receive the homogeneous and finely divided mass directly from grain forage that is very important for preparation of milk replacer. New equipment gives the chance to lower power consumption on 17%, to receive economic benefit. During testing of developed of milk replacer-1 (used for calves feeding since one month old) and milk replacer-2 (used for calves feeding since two months old) and their comparison with the whole milk replacer Kalvolak (the Netherlands) it was revealed, that indices of a daily average weight gain in calves of the first group fed with foreign milk replacer, and in calves of the second groups, which were fed with the national milk replacer, did not show authentic differences (806 and 816 g). However, the prime cost of 1kg of live weight gain in the second case was on 43% cheaper than in the first one. The cost price of 1kg of live weight gain of calves on expenses for fodder units in trial group was on 33% cheaper in comparison with the control group

Studying of influence of various levels of selenium on growth, protein structure of blood serum, natural resistance, and reproductive performance of pedigree bull-calves was realized in the conditions of the Republic of Belarus. It was established, that feeding with an optimum dose of selenium (0,4 mg per 1 kg of dry matter) in rations of replacement bull-calves during the raising period promoted the increasing of daily average weight gain on 6,8%, indexes of natural resistance - on 0,5-13,9%, and sperm production quality - on 4,5-27,3%. In the conditions of optimization of selenium level of in diets the protein structure of blood serum of replacement bull-calves exceeded the similar index at control animals by the crude protein index - on 8,3 (Р less than 0,05), by albumine and alpha globulin -on 2,2% and 1,6%, respectively. Application of selenium in dose of 0,4 mg per 1 kg of dry matter made it possible to increase the indexes of natural resistance on 0,5-13,9%. Increase of selenium dose up to 0,4 mg per 1 kg of dry matter in made it possible to increase the quantity and quality of sperm of bull-calves, that was proved by the increasing of ejaculate volume on 4,5%, concentration of male germ cells in ejaculate – on 15,7% (Р less than 0,05) and male germ cells activity - on 7,3% (Р less than 0,001)

Determination of the efficiency of young fat stock feeding with wet rolled maize grain which was preserved by means of different preparations was realized in the conditions of the Republic of Belarus. The following preserving agents were applied: HV-2 (by- product of amino-formaldehyde resin); AIV 3 Plus (mixture of 62% formic acid and 24% ammonium formate; KEMIRA, Finland); carbamide (30 kg/t) with 40 g/t of complex mineral supplement. Feeding of young fat stock with rolled maize grains preserved by NV-2 promoted the increasing of nutrient digestibility on 1,5-5,0%, nitrogen use - on 2% in comparison with control. Application of rolled maize grain preserved with AIV-3Plus and carbamide with the complex mineral supplement made it possible to increase the digestibility of nutrients on 1,0-4,8% and nitrogen use - on 1,6-1,7%. Introduction of rolled maize grain preserved with NV-2 into rations of bull calves increased their productivity on 4,7% (P less than 0,05) with the simultaneous lowering of forage expenses on 1,9%. Application rolled maize grains preserved with AIV-3Plus made it possible to increase daily average weight gain on 3,8% and lower the forages expenses on 2,6%. Use preserved with NV-2 and AIV-3Plus rolled maize grains in rations of young fat stock lowered the production cost price on 11,9% and 10,8% that proved the efficiency of the studied fodder

Evaluation of maize (Zea mays) silage prepared in combination with biological preserving agent Laktotim and calculation of its economic efficiency were realized in the conditions of the Republic of Belarus. Application of Laktotim rendered positive influence on forage dry matter content, on nutritive substance safety, and made it possible to increase the organoleptic indicators of silage. Use of the maize silage prepared with the preservative in a cow ration has positively affected their dairy efficiency. Cow milk yields have raised on 4,5%. Application of the preparation for silage making of green maize mass proved to be economically worth. The realized toxicological estimation of biological preserving agent Laktotim did not reveal any signs of preparation toxicity. Introduction of the preparation into mice stomach in a single maximum dose (25000 mg/kg; 12500; 5000 mg/kg of body weight), as well as application of the preparation in mixture with water in ratio which in 100 and 200 times exceeded the standard ratio in plant green mass, did not cause destruction of experimental animals. According to classifications of All-Union State Standard 12.1.007-76, the preparation Laktotim belongs to the4 class of danger - low-hazardous substances (LD50 over 5000 mg/kg)