Complex analysis of maize (Zea mays) yielding capacity and content of nutritive substances in silage and green mass depending on the phase of crop development and sowings damage due to frost was realized in the conditions of the Republic of Belarus. Yielding capacity of green mass in the analyzed sowings of hybrid maize Beliz on sod-podzolic light loamy soils was 75,1 n/ha at the stage of grain formation. Insufficient amount of positive temperatures at the beginning of vegetation stage was compensated by means of favourable weather conditions for growth and development of maize in July-September. In proportion to maize crops maturity there was stated the appropriate lowering of green mass. Taking place frosts lowered moisture content in crops. Yielding capacity of maize top biomass after cold spell was from 45,7 up to 44,8 c/ha. For the obtaining of the optimal amount of nutritive elements in the conditions of Vitebsk region of Belarus it was proposed to realize crop harvesting at the stage of milky-wax ripeness. The best composition of nutritive elements in silage was at the stage of milky-wax ripeness

Investigation of morphological changes in bone marrow of young hens in the conditions of application of associated virus vaccines and sodium thiosulphate immunostimulant was realized in the Republic of Belarus. The associated virus vaccine was applied against infectious bursal disease, infectious bronchitis, infectious laryngotracheitis, and Newcastle disease. Research results showed that under the influence of inactivated vaccine against mentioned above diseases there was noted the increasing of quantity of granulocytic cells, there was stated an active hyperplasia of pseudoeosinophil cells. Immunization of young hens with the presented vaccine developed in the Institute of Experimental Veterinary Medicine of the National Academy of Sciences of Belarus promoted a short-term increasing of leucoerythroblastic index. Application of an alternative vaccine developed by Scientific and Production Enterprise Avivak did not render substantial influence on the morphology of bone marrow of chickens. Sodium thiosulphate applied in combination with associated vaccines (in 7% concentration in vaccine) caused the hyperplasia of lymphoid and thrombocyte cells, strengthened the proliferation and maturity of granular leukocytes

Investigation of peculiar features of productive and reproductive qualities (milk producing ability; reproductive qualities; live weight at different ages) of milking cows of white-and-black breed was realized in the conditions of CJSC Lipovtsy of Vitebsk region of the Republic of Belarus. On the basis of obtained results there was calculated the selective differential of milk yield and butter-fat yielding capacity which were increased by means of maternal and father's cattle; genetic progress through selection in reliance on generation and target standard for the analyzed herd, as well as the minimal requirements to first-calf heifer productivity.Research results showed that average milk yield in the analyzed herd was 5204 kg with average butterfat percentage 3,59%; for first-calf heifers – 4838 kg with butter-fat yield of 3,47%. Productivity of first-calf heifers and cows was higher than the standard valuation requirements to milk yield on 1350-1588 kg

Evaluation of amino-acid, mineral, and vitamin content, as well as indexes of meat safety obtained from young stock of cattle of different genotypes in accordance with possibility of its application as raw material for baby food production was realized in the conditions of the Republic of Belarus. In course of study there were used bull calves of white-and-black breed, Limousin breed and their crossbreeds. Research results showed that young stock of Limousin breed, Limousin x white-and-black crossbreds, and white-and-black breed (control group) gave high quality meat. In meat of animals of experimental groups there was stated high quality of almost all nonessential amino acids and nonreplaceable amino acids, in meat of crossbreeds there was noted considerable increasing of polyunsaturated fatty acids. In it there was 12,31% of linoleic acid against 4,75 in Limousin breed and 2,77% in white-and-black breed; and eicosatetraenoic acid – 2,4% against 1,24% and 0,7%, respectively. Also in meat of experimental bull calves there was stated higher content of vitamins, calcium and phosphorus, while the content of cuprum and zinc decreased

Determination of genetic structure of different population lines of Belarusian white-and-black breed in accordance with locus of kappa-casein gene (CSN3) was realized in the conditions of the Republic of Belarus. In course of study there were used DNA samples of Belarusian white-and-black breed cows (380 samples) and bioprobes of servicing bulls (83 samples). With the help of endonuclease Hindill there were revealed two alleles of kappa-casein (A and B) in DNA preparations. As a result of genetic typing of breeding animals by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods there were revealed three genotypes CSN3**AA, CSN3**AB, and CSN3**BB. The frequency of occurrence of desirable genotype CSN3**BB of Belarusian white-and-black breed of cows depending on breed and linear pertain varied from 2,2% up to 7,69%, for servicing bulls – from 0 up to 11,1% . The majority of homozygotic cows with undesirable cow genotype CSN3**AA belonged to the following lines: of Ruties Edward (2,31646 - 92,3%), Niko (86,0%), Vis Ajdal (933122 - 71,9%), Reflection Sovereign (198998 – 63,9%). The desirable CSN3**BB genotype in most of the cases was stated at Annas-Adema (30587) and Hiltes-Adema (37910) lines. Presence of heterozygote genotype predominated in Annas-Adema (46,1%) and Montvik Chiftein (36,3%) lines. Realized analysis of cow population lines of Danish and Holstein breeds showed that the average frequency of occurrence of CSN3**B allel was 17%, but lower concentration (15%) of CSN3**b allel was typical for the Danish breeds. Frequency of occurrence of CSN3**B allel in Holsten lines was 18%. In was revealed that in 86,6% of cases bulls were the genetic carriers of CSN3**A allel and only 11,4% of animals had the desirable allel CSN3**B in their genotype

Morphological indexes in immune system organs of piglets which were vaccinated which were immunized by SPS vaccine (against salmonellosis (Salmonella), pasteurellosis (Pasteurella) and streptococcus) in combination with immunostimulative drugs and without them were studied in the conditions of the Republic of Belarus. Piglets of the first group were vaccinated against salmonellosis, pasteurellosis and streptoccocusis by SPS vaccine. Piglets of the second group were vaccinated by SPS vaccine in combination with vitamin C. Piglets of the third group were vaccinated by SPS vaccine with immunotstimulant sodium thiosulphate. The fourth (control) group of animals was administrated with normal saline. Animals were immunized twice, intramuscularly with 7 day interval and in dose 4 ml (primary), 5 ml (secondary). Vitamin С was added in dose 0,05g per head. Research results showed that immunization by SPS vaccine with sodium thiosulphate and Vitamin С activated the morphological reaction of immune system. Application of Vitamin С and sodium thiosulphate (30% concentration) in combination with SPS vaccine promoted the increasing of lymphoid nudels in lymphodnudus and lien, increasing of plasma cells quantity in 1,3-2,2 times, activation of micro- and macrophage reaction in 1,5-2,8 times in comparison with vaccinated animals

Experimental application of a vaccine against salmonellosis, pasteurellosis, and streptococcosis (SPS) for piglets of 30-35 days was realized in the conditions of the Republic of Belarus. Research results showed that administrationof sodium thyosulphate and vitamin С in combination with SPS vaccine promoted the statistically-valid increasing of preventive properties of blood serum of piglets and increasing of titers of specific antibodies to agents of pasteurellosis and a salmonellosis in 1,3-2 times, as well as increasing in blood serum of quantity of immunoglobulins and to reduction of quantity of globulins.

After the pathomorphological and histological studies of innards of fallen experimental animals in all realized experiments it was found that sheep and lambs infected with pneumoviral infections (Parainfluenza-3, Adenoviridae, respiratory streptococcosis infection) with their additional infestation with radioactive substances there was stated the acceleration of infectious process, and disease recrudesced up to 2-5 and more times (depending on irradiation doze). The immunity of sheep and lambs decreased caused by reproduction of viruses, and in acute cases animals died but in cases of mild forms the disease transformed into chronic form and caused animal death.

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 morphological characteristic and parameters of a thyroid gland of a thyroid gland of growing cattle stock made it possible to specificate the age-specific and species-specific parameters of adaptation of cattle in concrete conditions of environment was realized in the conditions of cattle breeding complexes of the Republic of Belarus. As a result of studies there were obtained new data on form-building processes, macromorphology, topography and referential parameters of thyroid gland of cattle breeds.