Serological properties of leptospirae bacteria grown on differential nutritive media were studied by the example of sheep in the conditions of the Republic of Belarus. In the experiment there were used 6 pathogenic industrial leptospirae stock: Leptospira pomona VGNKI-6; Leptospira tarassovi VGNKI-4; Leptospira grippothyphosa VGNKI-1; Leptospira icterrohaemorragia VGNKI-2; Leptospira conicola VGNKI-3; Leptospira hardjo VGNKI-5. The results showed a serological difference of leptospirae grown on conventional and experimental media derived from ram's blood.

The realized studies of an experimental series of inactivated vaccine showed that the developed biological preparation made it possible to achieve high preventive efficiency in the conditions of cows heavy with calves for the creation in newborn calves the expressing immunity after milk feeding in the first hours of their life. As a result realized in the conditions of the Republic of Belarus production experiment of emulsified vaccine against rotavirus infection and colibacillosis of cattle in animal breeding farms of different regions of the Republic the prophylactic efficacy of a developed vaccine made up 97,9-98,9%. Research results showed that the developed inactivated vaccine caused at the immunizated animals the formation of specific antibodies at a higher level in comparison with other analyzed national and foreign analogue preparations.

Data on changes of infectious titer of Porcine Reproductive & Respiratory Syndrome (PRRS) virus depending on variability of cultivation conditions was analyzed in the conditions of the Republic of Belarus. There were determined the regimes of cultivation which made it possible to minimize the terms of virus containing material production up to 3 days. The following factors influenced the infectious titer of PRRS: adaptation to cell culture; completeness of cell culture monolayer; number cells moving into stage of logarithmic growth; infectious dose of virus; storage duration; usage intensity.

Investigation of histological structures of liver of fattening broiler chickens after application of concentrate of E and F vitamins produced on the basis of rapeseed oil was realized in the conditions of the Republic of Belarus in order to evaluate their efficiency for prophylaxis of massive hepatic necrosis. Research results showed that application of the vitamins on the basis of rapeseed oil promoted the support of structural properties of hepatic cells that proved their higher antioxidant efficiency in comparison with synthetic vitamin analogues

A description of a method of chemical inactivation of Aujeszky's disease virus by teotropin was studied in the conditions of the Republic of Belarus. The developed inactivated viral suspension was tested for its antigenic activity. On the basis of realized experiments there were determined the optimal parameters of inactivation of Aujeszky's disease virus y means of 0,1% solution of teotropin under temperature of 37 deg C, pH 7,8 and duration of exposition of 24 hours. There were studied indexes of antigenic activity of inactivated virus

Research results showed that in the conditions of correct organization and application of technological methods of livestock breeding and feeding it was possible to achieve high livability rate of sheep and lambs up to 90%. Also it was possible to get a substantial break of infection chain of many sheep diseases (especially those which had a respiratory nature). Research results showed that simultaneous application of convalescent-phase serum against sheep acute respiratory diseases, as well as Nitox 200 and Invamek for treatment of sheep and especially 2-3 month old lambs with respiratory infectious diseases promoted the recovery of 80-100% of animals.

In the conditions of immunization of swine by experimental produced at Vitebsk Biofactory in the Republic of Belarus vaccines in blood of experimental swine there stated the morphological changes which pointed to formation of immune response.

Analysis of national studies and literary sources on problems of haemophilus pleuropneumoniae of swine was realized in the conditions of the republic of Belarus. Research was realized in the conditions of Agricultural Production Co-operative Uritskoe (Gomel region, Belarus). It was established that medical actions gave positive result only at early stages of disease.

Results of studying the local of irritating properties of preparative forms of marsh cinquefoil (Comarum palustre) which were intended for treatment of parasitic of diseases of animals, namely, strongylatosis of gastro-intestinal tract of sheep and calves realized in the conditions of the Republic of Belarus were presented. Preparative forms of Comarum palustre (liquor, tincture, liquid extract and powder) had poorly expressed irritating properties after application into skin of animals and weak irritating action, excluding native forms of tincture and liquid extract on mucous coat eye, that confirms their low toxicity action as a whole on organism of animals.

Development of a new national preparation for the preventive maintenance of cow mastitis, fissures of milking tubes skin of cow udder was realized in the conditions of the Republic of Belarus. The preparation Maz' Solnechnaya ("Unguent Solnechnaya") did not contain antibiotics, hormones and other synthetic components. Natural components of a preparation provide long anti-inflammatory action, stimulate local blood circulation, regeneration of epidermis and accelerate processes of healing of microtraumas. Besides it possesses high efficiency at preventive maintenance of mastitises at cows.