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%

Analysis of the optimal scheme of doses and rates of combined administration of probiotic Dialakt and immunostimulant Alveozan was realized in the conditions of the Republic of Belarus by the example of 1500 broiler chickens of cross Kobb- 500. Chickens of the first (controlled) group were given only total ration, balanced with the main nutrients. For the chickens of the second group were administrated with immunostimulant Alveozan with water starting from one day old age, every day in dose of 10 mkg/kg of body weight once a day in course of 5 days successively and with 7 days interval till the end of growing period; and probiotic Dialakt was administrated with water in dose of 0,1-0,2 ml/head (10,0-20,0 mln microbial bodies) starting from one day old age, once a day in course of 5 days successively and with 6 and 14 days intervals till the end of growing period. Chickens of the third group were administrated Alveozan in dose of 10 mkg/kg of body weight with drinking water once a day in course of 5 days with 10 days interval till the end of growing period; and Dialakt in dose of 0,1-0,2 ml/head with drinking water starting from one day old age, every day in course of 5 days with 6 and 14 days interval till the end of growing period. The research results showed the following optimal regime of complex application of the analyzed preparations: immunostimulant Dialakt - in dose of 0,1-0,2 ml/head with drinking water starting from one day old age, once a day in course of 3 days successively with 6 and 14 days intervals till the end of growing period; and immunostimulant Alveozan - in doze of 10 mkg/kg of body weight with drinking water once a day in course of 5 days with 10 days interval till the end of growing period. Complex application of Dialakt and Alveozan promoted the increasing of organometric indexes, specific volume and size of thymus in 1,5-1,8 times (P less than 0,01), Fabritsiya bursa - in 2 times (P less than 0,01) and lien - on 11,1% (P less than 0,05)

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

The purpose of research is to study influence of fodder additive Water Trit liquid on dynamics of live weight, natural resistance and determination of an optimal dose for pigs on growing. Thanks to рН decrease of intestines contents and presence of organic acids the additive is applied for disease prevention. Presence of organic acids stimulates the development of useful Lactobacillus micro flora in intestines gleam. From the received data positive influence of the fodder additive on a gain of body weight is visible. In the beginning of experiment the difference in body weight of a control and a trial groups was insignificant and made from 9,2 kg to 9,4 kg in the experimental group, and 9,3 kg - in the control group. In the end of experiment the difference in body weight was essential: 28,6 kg, 30,5 kg, 29,5 kg in the trial groups and 28,05 kg in the control. After application of the fodder additive Water Trit liquid in the trial groups there were noted the raised daily average weight gains: on 2,6% in the second, on 13,4% (P less than 0,05) - in the third and on 8,5% - in the fourth group in relation to control group. For studying of the influence of the fodder additive on animal organism there was carried out the blood testing: phagocytosis, bactericidal activity of blood serum, lysozyme activity of blood serum. Indexes on phagocytal index at animal of the control and trial groups were in the beginning of experiment approximately at one level. At 45-day age the indexes in the second and fourth trial groups were above the control ones on 5,2% and 8,9%, respectively. By the end of the experiment the phagocytal index in all four groups changed insignificantly. At studying of lysozyme activity of blood serum at pigs the given research have shown, that at 30-day age the indexes in the third and fourth trial groups were above the control, and indexes in the first group were above the standard of the control. At 70-day age the highest lysozyme activity of blood serum was in the second trial group and has made +16,0% to the control. It is necessary to notice, that on the 70th day this indicator was above the control in all three trial groups

In the conditions of the Republic of Belarus there was studied the nonspecific resistance of lambs of Latvian Black Face breed during the colostrum and milk fed period of their growth development. In course of the experiment there were used 10 newborn lambs. Analysis of resistance was realized in accordance with a scheme: before colostral milk sucking; in 6, 12, 24 hours; in 3, 7, 14, 21 days; in 1, 2 and 3 months after birth. In lambs during the colostrum and milk fed period of growth there were marked two critical periods, which were characterized by low indicators of resistance: before colostral milk uptake and at 7-21 day-old age. Increasing of leukocytes, bactericidal, lysozymic activity of blood serum, phagocytal activity of leukocytes, crude protein and antibodies in the first days of lamb life took place due to their entrance in blood with colostral milk, just because at this time the intestines wall possessed ability to transit in native condition the antibodies, enzymes, and leukocytes. At 7-21 day-old age in connection with reduction of these factors quantity of in colostral milk, and also due to reduction of intestines capacity, their was stated that their entrance in blood of newborn lambs decreased, but at 3 month old age of lambs there were stated to form internal protective factors of resistance because of which their quantity in blood started to increase.