Immunomorphological changes in young hens vaccinated with an associated inactivated emulsion vaccine against bursal disease, infectious bronchitis and Newcasle disease was realized in the conditions of the Republic of Belarus. Replacement young hens of 130-158 days old were divided into 2 groups with 200 head in each according the analogue principle. At the age of 130 days old the first experimental group of chickens was immunized against bursal disease, infectious bronchitis and Newcasle disease with a liquid inactive emulsion vaccine (produced in the republic of Belarus) in dose of 0,5 ml intramuscularly. In course of the experiment chickens from each group were killed on the third, seventh, fourteenth, twenty-first and twenty-eighth days. For the analysis of immunomorphological reaction there were tested tissue pieces from the places of vaccine administration, as well as thymus, bursa of Fabritius, lien, cecal tonsils and Garder's gland. Research results showed that in tissues in places of the vaccine administration there were developed hemorrhages, serous inflammatory edema, necrobiosis and necrosis of muscular fibers, inflammatory cellular infiltration, and moderate plasmocytic reaction. At a later stage at the places of damaged structures there was noted the development of granulation tissue with presence of some lymphoid nodules. In response to vaccination in the central organs of poultry immunity there was stated the sinuated changes of morphological indexes. Immunization of chickens against infectious bursal disease, infectious bronchitis and Newcasle disease promoted the increasing of absolute weight of lien, activation of blastic and plasmocytic reaction in bursa of Fabritius and lien and did not render substantial influence on immunomorphological indexes of cecal tonsils and Garder's gland

Investigation of immunity of broiler chickens of Kobb-500 cross vaccinated by national associated viral vaccine and foreign (ABIC, Israel; Vitex XXI vek Seva) vaccines against Newcastle disease and infectious bronchitis was investigated in the conditions of the Republic of Belarus. In course of studies there was analyzed the content of immunoglobulin in blood serum, as well as the influence of living vaccines on immunity formation. Research results showed that broiler chickens immunization against Newcastle disease and infectious bronchitis by national and foreign vaccine produced by ABIC company made it possible to increase the phagocytic activity of pseudoeosinophils, bactericidalal and lysozyme activity of blood serum, that proved the activation of nonspecific protection factors. At the same time in blood serum there was stated the increasing of immunoglobulin number in 1,5-3,0 times in comparison with control groups. Economic efficiency of all analyzed vaccines was analyzed

Influence of potassium orotate on hematological, immunomorphological indexes and and marrowy myelopoiesis of broiler chickens in the process of oral associated immunization against infectious bronchitis and poultry Newcastle disease was investigated in the conditions of the Republic of Belarus. There were studied 60 broiler chickens divided into 3 groups: one control group and two experimental ones. Research results established that potassium orotate application in combination with associated poultry immunization against infectious bronchitis and Newcastle disease increased the number of leucocytes and the volume of adenoid tissue as well as raised the lymphocytes density in thymus and bursa of Fabricius. In the bone marrow aspirates in 7 days after immunization in the control group there was stated the increasing of basophilic myelocytes number in comparison with the second experimental group. In 14 days in the control group there was noted the increasing of a total number of basophiles. In 21 days after immunization there were stated no considerable changes in the composition of basophil cells in the experimental groups. Research results showed that potassium orotate intensively stimulated the development of plasmocytic reaction in the conditions of multipartial immunization

For the well-timed prevention and treatment of sick animals there was analyzed the therapeutic efficiency of a produced survivor serum against acute respiratory diseases of sheep and lambs, as well as Catosal in combination with Nitox 200 against the mixed flow of parainfluenza-3, adenovirus, respiratory syncytial, chiamydial and pasteurellosis infection. Comparative efficiency of all mentioned preparations was presented. Research results showed the correct and timely application of drug preparations as well as their qualitative selection made it possible to lower the death cases. Application of the presented survivor serum in combination with Nitox 200 and Catosal made it possible to lower the loss of cattle in 4-5 times and increase the viability rate of animals