Studying of efficiency of application of modified scheme of hyperimmunization of bull-producers with a designer salmonella polyantigenin in comparative analysis with the production scheme of hyperimmunization was realized in the conditions of the Republic of Belarus. Research results showed that engineered polyvalent antigen for hyperimmunization of producer bulls contained in their formula the following serovariants of salmonella in 1:1 ratio: S. typhimurium 371, S. dublin 373, S. choleraesuis 370, and S. enteritidis CB. The obtained antigen was sterile, harmless and had pH 7,3. Hyperimmunization of producer bulls in the experimental scheme revealed in increasing of leukocytes quantity on 57,3 %, banded neutrophils on 86,7 %, B-lymphocytes - on 42,2 %, content of total protein - on 25,6 %, content of Ig G - on 77,8 %, lg M - on 51,6%. After the fifth administration of antigen there was stated the lowering of agglutinating activity of blood serum on 25%, content of Ig G - on 54,4%, Ig M - on 14,6 %, that indicated to the inefficiency of antigen administration and became the basis for termination of hyperimmunization cycle. Immunobiological reaction of bull-producers which were hyperimmunized by the suggested scheme differed from reaction of animals which were hyperimmunized by the production scheme: content of total protein increased on 10,1%, protein content - on 27,3 %, content of lg G - on 24,8 %, lg M - in 23,7%

Growth and development of mixed bred Charollais x white-and-black young stock and black-and-white bull-calves since 8-month old age till and 15-month old age were studied in the conditions in the Republic of Belarus. In course of studied there were analyzed linear growth; young stock growth intensity; forage consumption; efficiency of experimental results. On the basis of obtained data there was determined the absolute growth rate of bull-calves at certain growing periods. Research results showed that dramatic changing of technology of management and feeding of mixed bred Charollais x white-and-black young stock bulls after weaning period caused the decrease of daily average live weight gain from 8-month old age till and 15-month old age in comparison with white-and-black cattle on 99 grams or 14%. Analysis of exterior of experimental animals confirmed the priority of mixed bred young cattle over white-and-black herdmates. They were characterized by massive corpus, wider and deeper barrel, wide withers, back and coupling

Application in diets of breeding bull calves of an optimum dose of selenium (0,4 mg on 1 kg of a solid of a diet) renders positive influence on formation of reproductive ability of bull-calves: promotes increase daily average gains live weight on 7,1%, indicators of natural resistance – on 0,6-6,7% and to improvement of quality sperm production – on 16,4% during the winter period. During the summer period daily average gains live weight on 6,8%, indicators of natural resistance – on 0,5-13,9% and to improvement of quality sperm production – on 15,7% accordingly

The research in RUP Scientific and Practical Center of Animal Breeding of National Academy of Sciences on such parameters as consumption of forages, processes of rumen digestion, morphological and biochemical structure of blood has shown that usage of wet grain preserved with Kormoplus for young cattle fattening has a positive effect on physiological condition and digestibility of nutrients and promotes nitrogen usage by animals that increases at 7,0 and 1,6%

Feeding replacement calves of 369-460,8 kg of live weight with diets of non-degradable protein level that is 10% higher than approved norm increases metabolically energy transformation into weight gain energy from 19,10 to 20,81 MJ or at 9% that promotes increase of average daily weight gains at 5% and decrease of energy spends at 5% counted per 1 unit of energy for weight gain. Ejaculate volume is increased at 14% and sperm concentration – at 12%

Addition of 0,01 mg/ml epibrassinolid in 100 ml laktoza-gliceryn-yolky thinner during the autumn-winter period has resulted, on the average on groups of bulls, to mobility increase sperms on 10,6 %, the survival rate sperms has increased by 17,9 %, the quantity pathological sperms has decreased on 32,5 %, safety sperm cover has increased by 4,5 %, resistance sperms has raised on 15,6 %, discoloration time blues has decreased on 8,5 %, has allowed to raise percent insemination cows and the calf on 12%

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)

Influence of various levels of the organic form of selenium of Sel-Pleks on the formation of reproductive function of breeding bull-calves is studied in the conditions of the Republic of Belarus. Feeding of organic selenium to bull-calves promoted volume increase of ejaculate on 5,0%, quantities of male germ cells in ejaculate - on 9,1% and concentration of male germ cells in ejaculate - on 7,5% in comparison with animals in which rations sodium selenit was used. Application in winter period of the premix with inclusion of selenium in a dose of 0,4 mg per 1 kg of a dry matter of a ration allows to increase the quantity and quality of sperm of bull-calves: volume ejaculate - on 9,5%, concentration of male germ cells in ejaculate - on 16,4% (Р less than 0,05) and activity of male germ cells - on 8,9% (Р less than 0,001). Increasing of a dose of selenium up to 0,4 mg per 1 kg of a dry matter in rations of bull-calves in summer period allows to increase quantity and quality of sperm. At bull-calves of the third experimental group the ejaculate volume has increased on 4,5%, concentration of male germ cells in ejaculate - on 15,7% (Р0,05) and activity of male germ cells - on 7,3% (Р less than 0,001).

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.