Determination of productivity and natural resistance indexes of laying hens after application of dry multienzyme preparation Vitazim (xylanase, 3600 units/g; cellulose, 3000 units/g; beta-glucanase, 7000 units/g); as well as the specification of optimal doses the enzyme were realized in the conditions of the Republic of Belarus. Research results showed that the best indexes of egg yields of laying hens were obtained after application in the main poultry diet of enzyme preparation Vitazim in dose 500 g/t that made it possible to increase the productivity in the experimemtal group on 12%. Application of Vitazim also promoted the increasing of natural resistance level of laying hens. There was stated the positive effect of Vitazim on bactericidal activity of blood serum. Before the beginning of test this index was the level of 44,35+/-0,92 – 56,52 +/-1,63. By the 300-th day of life the bactericidal activity of blood serum in experimental group administrated Vitazim in dose 300 g/t exceeded the control idexes on 3,8%; in the second experimental group (Vitazim in dose of 500 g/h) – on 29,5%; in the third experimental group (/vitazim on dose of 700 g/h) – on 23,7%.Vitazim administration also exercised positive influence on lysozyme activity in blood serum of lying hens

Determination of influence of polymorphism of gene of erythropoetin receptor (EPOR) on productive qualities of sows and reproductive characters of boars of Belarusian meaty breed was realized in the conditions of the Republic of Belarus. Research results proved the possibility of EPOR gene application as a genetic marker which determined productive abilities of swine of Belarusian selection breed. Frequency of undesirable allel EPOR**c of EPOR gene in the analyzed swine stock balanced within the frames of wide range: from 44% for Belarusian meaty breed sows up to 78% for Belarusian Kripnaya Belaya breed sows. Analysis of influence of genotype with EPOR gene on multiple fetation of sows of Belarusian meaty breed showed that sows with the preferred genotype (EPOR**tt) statistically reliable (P less than 0,01) exceeded sows with undesirable genotype (EPOR**cc) in accordance with number of alive birth piglets on 1,7 heads. Among sows of Belarusian Kripnaya Belaya breed with genotype EPOR**ct there were stated multiple fetation indexes exceeding the sows with genotype EPOR**tt on 0,5 heads. Desirable EPOR**tt genotype irrespective of sow age rendered the positive influence on their multiple fetation. It was recommended to realize genetic testing on determination og polymorphism of gene of erythropoetin receptor among the animals of Belarusian meaty and Belarusian Kripnaya Belaya breeds. Selection of parental pairs of the selection nucleus was recommended to realize taking into consideration genotypes, giving preference to animals with EPOR**t allel

In course of realized in the conditions of the Republic of Belarus evaluation of growing intensity and level of meat productivity depending on cattle sex there was conducted the scientific and economic experiment by an example of two groups of white-and-black bull-calves and heifer calves. In the first growing period the animals of experimental groups were fed with milk substitute. At the stage of completion of growing and fattening the bulls and heifers of experimental groups obtained ration containing haylage, plus 2 kg of flattened grains and 2 kg mixed fodders. Results of linear and weight indexes analysis showed that in changes of exterior of bulls and heifers of black-and-white breed there was noted a certain regularities in their growth and development. The most intensive growth and development of analyzed young cattle was stated at age from 6 till 12 months. At the same time, bulls exceeded heifers according to the main exterior indexes. According to the visual evaluation of bulls and heifers there were determined the differences in constitutional type

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

Analysis of influence of boar genotype by MUC4 gene on viability of progeny was realized in the conditions in the Republic of Belarus, as well as the evaluation of possibilities of association of polymorphic variants of gene with fattening and meaty qualities of obtained from the boars progeny were conducted. In course of studies there was analyzed the polymorphism of MUC4 gene at producer boars of studied breeds. There was revealed high occurring frequency of desirable allele MUC4**c and MUC4**cc genotype in all studied populations. Boars of Belarusian Meaty breed with genotypes MUC4**cc by MUC4 gene authentically (P less than 0,01) exceeded boars with genotype MUC4**cg according to piglet viability indexes at weaning period on 5,6%. For the further evaluation of the potential role of MUC4gene in marker selection there was realized determination of relations between genotypes of studied marker and other economic traits of swine (fattening and meaty traits of boar progeny). There was stated the authentic increasing of fattening and meaty traits of stores obtained from boars with homozygous genotype MUC4**cc in comparison with progeny fathers of which in their genotype had mutant allel MUC4**g. For the forecasting and modeling of genotypes resistant to colibacillosis there was presented a scheme of selection boars and sows of different genotypes by MUC4 gene for the increasing of progeny viability. According to the scheme the preferred selection was MUC4**cc x MUC4**cc. This selection was recommended for the self-replacement and creation of nuclear stock

Investigation of quality and quantity indexes of sperm production of boars of Yorkshire, Landrace, Duroc breeds of Danish selection was realized in the conditions of the Republic of Belarus. Quality and quantity indexes were analyzed in accordance with ejaculate volume, spermium concentration and activity at different age-specific periods in the comparative aspect. Thorough analysis of quality indexes (ejaculate volume; spermium concentration; spermatozoon motility; sperm quantity) of semen production of studied breeds at different age-specific stages (before 7 months old; 7-10 months; 10-12 months; 12 months and older) was presented. Coefficients of variation of valuation indexes of semen production were stated. Research results showed that the lowest ejaculate volume was typical for boars of Duroc breed, but the quantity of spermium in ejaculate of this breed since 10-month old age was the highest – 92,6 milliard, that made it possible for this breed of boars to take premier place according to the index of spermium quantity in ejaculate. The same index for boars of Landrace and Yorkshire at age of 12 months old and older was 77,5 and 76,3 milliards, respectively. High variability of indexes of evaluation of semen production was due the reason that the research was taking place at the period of formation of productivity over the whole pig stock. Research results proved that indexes of semen production of producer boars of Yorkshire, Landrace, Duroc breeds of Danish selection depended on the breed and high variability indexes

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

Determination of a degree of manifestation of immunomorphological changes in immune system organs of piglets vaccinated against salmonellosis, pasteurellosis and streptoccocusis with SPS vaccine (against salmonellosis (Salmonella), pasteurellosis (Pasteurella) and streptococcus) in combination with immunostimulative drugs and without them was realized in the conditions of the Republic of Belarus. Piglets of 30-35 days old were divided into 4 groups according to the analogue principle. 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 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 in dose of 4 ml (primary), and 5 ml (secondary). Vitamin С was administrated in dose of 0,05g per head. Sodium thiosulfate was administrated in combination with the vaccine in 30% concentration. The research results showed that immunization with SPS vaccine in combination with sodium thiosulphate and vitamin С promoted the activation of morphological reactions in tissues at locus of vaccine administration, lymphodnudus and lien. Immunization of piglets by SPS vaccine with sodium thiosulphate and with vitamin С activated the limphiod, micro- and macrophage reactions at locus of vaccine administration, as well as in organs and cells there was stated the well-marked vitamin C and glycogen distribution. Sodium thiosulphate showed higher immunostimulate influence in comparison with vitamin C

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

Selection of an optimal dose of Cryptosporidium parvum agents which were isolated from swine and could cause expressed changes in organs of experimentally infestated mice was realized in the conditions of the Republic of Belarus. Data about on persistence of homoxenous coccidia Cryptosporidium parvum at laboratory white mice and pathomorphological changes in the bodies of experimental animals were presented. In a mucous coat of intestines there was marked a catarrhal inflammation with mucous membrane necrosis and its infiltration by leukocytes and macrophages.