In the conditions of the Republic of Belarus the was studied the age-specific dynamics of content of total lipids, triglycerides, total cholesterol, phospholipids, total iron and catalase activity in spleen of broiler chicken during the incubation period (1-46 days). The content of total lipids, total cholesterol, and phospholipids was at maximal level at one day-old age, and gradually lowered by the end of growing period. The amount of total iron in ontogeny increased till the 30 day-old age and a bit lowered by the end of growing period. In broilers with lower live weight the iron content in spleen was lower during the whole growing period. The catalase activity had a wave-like character and depended on prophylactic vaccinations undertaken and the amount of lipids in tissues.

In the conditions of the Republic of Belarus there was analyzed the influence of inclusion into broiler chickens diets of probiotoc preparation Bifidoflorin zhidkij (liquid) and prediotic veterinary drug Biofon AIL on the natural resistance, hematopoiesis, growth, metabolic function, development and viability of broiler chickens. In course of the study there was analyzed the dynamics of total haemoglobin, total protein of blood serum, albumins and globulins of broiler chickens which were fed with veterinary drugs probiotoc Bifidoflorin zhidkij and prediotic Biofon AIL. Indexes of chicken viability and life weight gain were marked. Research results showed that application of the presented veterinary preparations rendered the growth promoting action, lowering of disease incidence, increasing of chicken viability, increasing of live weight gain and stimulation of metabolic processes in the most intense period of poultry growing. All these factors were expressed in highest degree after the combined application of the probiotic and prebiotic veterinary drugs.

In the conditions of the Republic of Belarus there was analyzed the efficiency of bactericidal action of tartaric acid aerosol for air sanitation of poultry buildings and increasing of broiler chickens viability. The bactericidal action was analyzed by the example of Staphylococcus aureus, Eschericia coli and Proteus vulgaris. In course of study there were analyzed biochemical indexes of blood and blood serum, lymphoid tubercle in proper mucous plate of trachea of broiler chickens after 6-time treatment with tartaric acid and Ekotsid C preparation. Research results showed that the analysed preparations did not render negative influence on metabolic indexes of broiler chickens and increase poultry viability. Application of tartaric acid did not cause pathomorphologic changes in tissues and organs of birds, stimulated the active proliferation of leucocytes in immune system organs (thymus gland; spleen; and lymphoid tissue).

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

Investigation of stress reaction response and productivity of poultry by means of stimulation of natural resistance by biologically active substances was realized in the conditions of the Republic of Belarus by an example of 4 experimental group of broiler chickens of Kobb-500 cross. The first group was a control one. Chickens of the second group were administrated preparation Vigozin twofold in dose of 1 ml/l with water in course of the first three days in 2 cycles and with interval of 8 days. Chickens of the third group were given the preparation with water in dose of 1 ml/1 in course of the first 3 days. The fourth group was given the preparation with water in dose of 1 ml/1 in course of the first 5 days. In course of observation over chickens there was analyzed their clinical state, mortality rate, weight gain, and meat yield. In course of study in chickens of experimental group the daily average weight gain was 37,8 g against 34,1 in control; average live weight – 1099,6 +/- 7,57 g against 95,98 +/- 0,50 g in control. In 46-day old broiler chickens the average daily weight gain was 46,2 g against 43,1 g in control, average live weight – 2166,94 +/- 0,49 g against 2021,08 +/- 1,05 g in control. Forage expenses per 1 kg of weight gain were 2,01 kg against 2,18 kg in control. Forage conversion was 7,8%. Research results proved the efficiency of application of Vigozin preparation: viability of chickens in the second group on increased 3,5%; the third group - on 1,7% ; in the fourth group - on 2,5%

Investigation of influence of probiotic Dialact and immunostimulant Alveozan on digesting of nutritive substances by broiler chickens of Kobb-500 cross, as well as control over their individual development were realized in the conditions of the Republic of Belarus. The first (control) group of chicken was given standard well-balanced ration. Chickens of the second group were administrated immunostimulant Alveozan in dose of 10 mkg/kg of live weight with drinking water once a day in course of 5 days, with 10 days interval till the end of the growing period. Chickens of the third group were administrated preparation Dialact in dose of 0,1-0,2 ml with drinking water once a day in course of 3 days, with 14 days interval till the end of growing period. Chickens of the fourth group were given Alveozan in dose of 10 microgram/kg of live weight once a day in course of 5 days with 10 days interval, and Dialact in dose 0,1-0,2 ml once a day in course of 3 days, with 6 and 14 days interval. Research results showed that complex application of probiotic Dialact and immunostimulant Alveozan increased the viability of chickens on 100%, average live weight - on 5,1%, average daily weight gain - on 5,1%. Administration of Dialact and Alveozan, both separately and in complex, increased the digestibility of nutritive substances of mixed fodders: application of nitrogen increased on 1,93-6,38%, application of calcium decreased on 10,41-12,54%, phosphorus use increased on 2,38%

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

Development of axial skeleton bones of meat type broiler chickens of Kobb-500 and Ross-308 crosses at the postnatal ontogenesis period was investigated in the conditions of the Republic of Belarus. In course of studies there were used broilers of 5 age groups (1 day old, 20 days old, 30 days old and 40 days old) which were selected in accordance with analogous principle with 10 heads per each group. Research results showed that live weight gain as well as axial skeleton weight gain of both crosses chickens increased wavily. The highest growth intensity of body weight and axial skeleton weight was stated at broiler chickens of Kobb-500 cross at the last age period. The opposite way, there was noted the increasing of axial skeleton growth for broiler chickens of Ross-308 cross at the age of 20 days. At the further age periods till the end of fattening-off there was stated the slowing of axial skeleton and body weight. In the period of 1 to 10 days there was stated an intensive growth of cervical spine of spinal column of broiler chickens of both crosses. High intensity of absolute weight growth of cervical spine of spinal column for Kobb-500 cross chickens was stated at the age period 30-40 days; for Ross-308 cross chickens - at the age 10-20 days

In article results of studying of efficiency and quality of poultry-fanning production under influence chitosan are considered. It is established that the preparation promotes safety increase on 0,5%, efficiency on 6% and biological value of meat on 20% at chickens whom gave to drink chitosan in a dose of 5 mg/goal from 32 day age it) comparison with the control. Such technological reception leads to decrease the receipt in an organism of a chicken of microtoxins, heavy metals, products of a metabolism of bacteria

Data on studying of efficiency of application of immunobiological preparations on efficiency and other clinical and biochemical indicators for chickens-broilers are cited. It is established, that their application to chickens-broilers promotes increase of biological value of fowl as foodstuff and is economically expedient. Application of a preparation the Biococktail-NK in an optimum dose 0,1 - 0,2 ml/goal (10,0-20,0 million microbic bodies) has allowed to increase intensity of growth of chickens-broilers by 3,5%, to lower forage expenses for production of a gain of body weight of 1 kg on 4,95%, to raise safety of young growth of birds on 3,4 % and to lower a case of birds to 1,6% (technological norm of 5%). The carried out calculations have shown, that introduction of the Biococktail-NK in a ration of broilers is economically justified, as safety of young growth in 4th trial group has raised on 3,4%, in the third - on 2,5%, in the second - on 1,3%. On the basis of the spent research fowl of the delivered samples in which ration it was entered the probiotic Biococktail-NK from calculation 0,1 - 0,2 ml/goal (10,0-20,0 million microbic bodies) since daily age within the first 5 days into 4 cycles with an interval of 7 days till the end of the cultivation period is established, that on organoleptic, physical and chemical, bacteriological indicators, and also biological value and harmlessness does not concede to meat of control group and is good-quality. In the literature there are data about influence of biologically active substances on growth and development of bird. Despite it, about influence of probiotical and immunostimulatory preparations as separately, and in a complex with probiotics, on an organism of chickens-broilers it is not enough data that induces carrying out of scientific research in the given direction. Simultaneous use of probiotics on the basis of an intestinal stick in rations of chickens-broilers is the perspective directions. Proceeding from it, working out of new effective ways of increase of chickens-broilers efficiency with a view of reception of ecologically pure and safe products of poultry farming is actual for poultry-farming economy of Belarus.