To evaluate economic effects and health and performance of the general cattle population after exposure to cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) in a feedlot. 21,743 high-risk calves from the southeastern United States. PI status was determined by use of an antigen-capture ELISA (ACE) and confirmed by use of a second ACE, reverse transcriptase-PCR assay of sera, immunohistochemical analysis, and virus isolation from sera. Groups with various amounts of exposure to BVDV PI cattle were used. After being placed in the feedlot, identified PI cattle were removed from 1 section, but PI cattle remained in another section of the feedlot. Exposure groups for cattle lots arriving without PI animals were determined by spatial association to cattle lots, with PI animals remaining or removed from the lot. 15,348 cattle maintained their exposure group. Performance outcomes improved slightly among the 5 exposure groups as the risk for exposure to BVDV PI cattle decreased. Health outcomes had an association with exposure risk that depended on the exposure group. Comparing cattle lots with direct exposure with those without direct exposure revealed significant improvements in all performance outcomes and in first relapse percentage and mortality percentage in the health outcomes. Economic analysis revealed that fatalities accounted for losses of $5.26/animal and performance losses were $88.26/animal. This study provided evidence that exposure of the general population of feedlot cattle to BVDV PI animals resulted in substantial costs attributable to negative effects on performance and increased fatalities.

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.

Investigation of antimicrobial activity of liquid extractions from the following medicinal plants and their mixtures against S. aureus, B. subtilis, E. coli, P. aeruginosa, and P. vulgaris was realized in the conditions of the Republic of Belarus: peat moss (Sphagnum); greater plantain (Plantago major); plumepoppy (Macleaya); common comfrey (Symphytum officinale); speckled alder (Alnus incana). Research results showed that the best results for septic wounds treatment were obtained apter application of mixture of plumepoppy and greater plantain as it showed the acute antimicrobial, anti-inflammatory, and wound-healthing effect. Antimicrobial activity of the analyzed infusion formula revealed in quicker (on 3-6 days in comparison with control) wound cleansing from microorganisms, quick lowering of bacterial content up to 10E3 bodies per 1 g of tissue and in provision of wound healing without inclusion of saprogenous microflora. Anti-inflammatory effect was characterized by quick (by 2 days) cancellation of acute inflammatory response, that was revealed in lowering of neutrophilic leukocytes quantity up to 59,8 +/- 0,49 %; quicker normalization hematologic indexes and early reduction of perifocal edema; weakening of hyperthemia and hyperemia; decreasing of wound secretion without purulence; absence of leaks and leak pouch; normalization of microcirculation in wound. Wound-healthing effect was revealed in increasing of fibroblast number from 7,1 +/- 0,4 % up to 29,4 +/- 0,4 % on the 7th day and in activation proliferate and synthetically function

Investigation of connection of experimental trichophytosis and relations between changes of clinical implications of disease and dimensions of some immunological indexes was realized in the conditions of the Republic of Belarus. At the first stage of the experiment there analyzed 48 guinea pigs (Cavia porcellus) infected with Trichopyton verrucosum. Phagocytic ability of phagocytes and level of circulating antibodies in indirect hemagglutination test were investigated each 5 days before and during disease. The second stage was realized by the example of 2,5-6 months old calves. In course of study there were analyzed blood and blood serum indexes, indexes of nonspecific resistance, as well as some indexes of cell-mediated immune response and antibody mediated immunity. Comparative analysis the following morphological and biochemical blood indexes of clinically healthy calves, calves after trichophytosis, and calves sick with mild, moderate and severe of disease were presented: erythrocytes; hemoglobin; leukocytes; basophils; eosinophiles; rods; microxyphils; lymphocytes; monocytes; ESR; total albumin; albumins; alpha globulins; beta globulins; gamma globulins; carotene; calcium; inorganic phosphorous; alkaline reserve; copper. The realized experiment made it possible to conclude that determination intensity of leukocyte absorption of microconidia of the agent, antibodies against the agent, and specific for cytoplasm fungus, morphological and biochemical blood indexes made it possible to control the development of inflammatory phenomenon in centers of infection, as well as to predict the formation of face, infiltrative and suppurant disease forms

Determination of influence of long acting antihelminthics (Aversictini boluses and boluses with albendazole) and influence of usual antihelminthics (farmatsin, alverm, fenbendavet) on first stomachanimal digestion, as well as on quantity and quality composition of microflora and microfauna in first stomach and large bowel was realized in the conditions of the Republic of Belarus. In course of the experiment there were used 6 groups of calves infested with helminths (Neoascaris vitulorum, Strongylata sp.). Research result showed that different antihelminth preparations to a greater or lesser degree rendered negative influenced on quantity and quality composition of microorganisms in first stomach and large bowel of cattle. Alverm and boluses with albendazole rendered the least influence on microflora and microfauna that could be explained by low toxicity of active substance (albendazole) of the above preparations. Aversictini boluses, fenbendavet, and farmastin changed the composition of microorganisms. It could be explained by high toxicity of preparations containing aversictini which rendered influence not only of gastro-intestinal tract but also on the whole organism. Active ingredient of mentioned above preparations (Aversektin C), being the product of microbial synthesis, rendered the antagonist action on the normal microflora of digestive tract. Negative influence of fenbendavet was caused by the chemical composition of the preparation and neurotoxic action of fenbendazol