Animal organism immunobiological reactivity increase, its resistance to technological stress factors for better use of animals and obtaining  their products is a common biological problem.

Among the substances that have the ability to stimulate the immune system, biologically active preparations are the leaders, namely: immune active components of bacterial cells, thymic peptides and hormones, bone marrow regulators of the immune system (myelopeptides and their analogues), polyelectrolytes, cytokines, etc.

The research aim includes theoretical justification for the use of exogenous immunomodulators in animal husbandry and conducting experimental studies to establish the influence of the Mobes preparation on immunological reactivity indexes and productivity of young cattle.

According to the developed scheme, the 1–3 days old calves in the first experimental group were twice injected subcutaneously in the middle third of the neck with 14 days interval by the immunomodulating  preparation KAFI (TU U 24.4-20573778-003:2007) with a dose of 0.015 ml / kg of body weight (optimal dose). This  preparation is used as a prototype to the Mobes  preparation. Young cattle of the second experimental group was injected by Mobes dose of 0.01 ml / kg body weight (optimal dose), and the control group animals – by isotonic solution NaCl similarly. Blood samples were taken before administration of the preparations, and on the 30-th and 60-th days of studies.

It was found out that from the 30-th day till the end of studies there occurred valid increase of the red blood cells number in experimental animals. The optimal indexes were noted in calves of the second experimental group after repeated administration of Mobes preparation: 6,12 ± 0,22 in the control group and 8,92 ± 0,36 t / l (Р≤0,001) in the experimental group. Hemoglobin content in erythrocytes of control animals in this period was 96,82 ± 4,16 g / l in, in the first experimental group it was 102,14 ± 4,22 (Р≤0,05) g / l, and in the second group – 111 44 ± 6,74 (Р≤0,001) g / l. The leukocytes content in the blood of control calves during the studies period ranged from 5,21 ± 0,64 to 9,14 ± 1,16 g/l. The leukocytes content in the blood of 2 months old calves of experimental animals was by 7,6 and by 13,3% higher as compared with the control analog.

There was noted a tendency for increase of both the absolute and percentage content of B-lymphocytes in young cattle of the first experimental group, which was injected by KAFI preparation, namely: the absolute content of these cells increased by 0,38 g / l and percentage – by 1,32%. In the second experimental group, that was injected by Mobes preparation, there was noted the probable increase in both absolute and percentage B-lymphocytes respectively by1,06 g/l and 7.5%. This regularity was kept in 2 months old animals. The BABS (bactericidal activity of blood serum) in the control group was 37,72 ± 2,14%, and in the 1 and the 2 experimental groups respectively 54,42 ± 2,34 and 58,64 ± 2,32% (Р≤0,001). The LABS (lysozyme acti-vity of blood serum) indexes grew by 6,8 (Р≤0,05) – 29,0 (Р≤0,001)% and phagocytic activity of neutrophils by 29,1 – 36,1 (Р≤0,01). IF increased by 1,3-1,9 times, and AF by 8,5-44,3 (Р≤0,05)%. The nonspecific antibody titer in the blood serum of control animals was 1: 4 and 1: 6, and in experimental animals it increased to 1: 6 and 1: 8, respectively.

The activation of immunological reactivity indicators reflected the positive productivity of animals. The obtained results indicate that calves survival in the control and the first experimental group was 90%, and in the second experimental group 100%. The average daily live weight gain of calves in the first experimental group was by 74,30 g (11,56%), and in the second experimental group of calves by 44,54 g (6,9%) higher as compared with control counterparts.

Key words: biotechnology, stress, resistance, cells, erythrocytes, leukocytes, immunomodulators, activation, productivity, survival, calves.