The influence of the complex application of nanocobalt and probiotic microorganisms of the genus Lactobacillus on the microflora of the cecum, its biofilm-forming ability, immune status, antioxidant defense and detoxication function of the liver and kidneys of the laying hens during the period of maximum productivity were studied in the dissertation work. The method of their correction was developed on the basis of the obtained results. In 2015–2017, the fall of the bird (technological waste) fluctuated within 6.32–9.15%, which in absolute terms ranged from 98,944 to 380,051 of poultry in four regions of the Western region of Ukraine.
The bioavailable dose of nanocobalt, investigated in acute and chronic toxicology experiments on rats, is 0.1 mg/kg body weight.
In the laying hens receiving probiotic and nanocobalt at a dose of 0.08 mg/kg body weight, the content of the cecum increased the amount of Lactobacillus spp., Bifidobacterium spp., Streptococcus spp. and E. coli respectively by 13.5 % (p < 0.01), 13.4 % (p < 0.01), 14.3 % (p < 0.01) and 12.0 % (p < 0,05) and decreased the number of Staphylococcus spp., Enterococcus spp. and Candida spp. respectively by 23.0 % (р < 0,001).
At the correction of the diet of laying hens with probiotic and nanocobalt at a dose of 0.08 mg/kg body weight the ability to form a low density biofilm in Streptococcus spp. by 5.2 %, Staphylococcus spp. increased by 10.0 %, Enterococcus spp. by 8.2 %, E. coli by 10.0 % and Candida spp. by 16.6 %, of average density in Streptococcus spp. by 7.2 %, Staphylococcus spp. by 9.6 %, Enterococcus spp. by 4.3 % and high density in Lactobacillus spp. by 26.9 %. At the same time, the ability to form low density biofilms in Lactobacillus spp. by 4.9 %, of the average density of Lactobacillus spp. by 22.0 %, E. coli by 10.1 %, Candida spp. by 6.6 %, of high density Streptococcus spp. by 12.4 %, Staphylococcus spp. by 19.5 %, Enterococcus spp. by 12.5 % and Candida spp. by 10.0 %.
By correction of the cellular immunity level with probiotic in combination with nanocobalt at a dose of 0.08 mg/kg body weight, the number of lymphocytes increased by 9.4 % (p .0.01), T cell by 6.7 % (p < 0.05), B cell 6.6 % (p < 0.001), T helper cells by 3.8 % (p < 0.01), 0 cells per 4.4 % (p < 0.01) phagocytic activity was 4.1 % (p < 0.001), the phagocytic index was 21.8 % (p < 0.001) and the number of T suppressors decreased by 1.7 % (p < 0.001).
By correction of the humoral immunity of the probiotic together with nanocobalt at a dose of 0.08 mg/kg body weight, the γ- and β-globulins level increased significantly by 5.7 and 1.9 % (p < 0.05), the total number of immunoglobulins by 15,0 % (p < 0.05), Ig G, Ig A, by 15.1 %, 15.1 % (p < 0.01) and Ig M by 14.5 % (p < 0.05), and no probable changes in the level of CIC and serum counts have been identified. In this case, the SBA and SLA increased by 10.3% and 4.5 % respectively (p < 0,001).
It has been established that application of probiotic and nanocobalt at a dose of 0.08 mg/kg body weight to laying hens contributed to an increase in the number and size of lymphoid nodules in the spleen, accumulation of pyroninophilic lymphocytes and plasma cells around the pulpal arteries; in the thymus — the preservation of a clear division into cortical and cerebrospinal fluid, the densely placed thymocytes in the cortex, the proliferation and differentiation of plasmacytes in the brain, and the slowing down of the involution of the organ. The pronounced immunostimulatory effect of probiotic and nanocobalt at a dose of 0.08 mg/kg body weight was also noted on the lymphoid tissue of the cecal tonsil, as indicated by a significant number of primary and secondary lymphoid nodules with dense placement of lymphoid cells and an increase in the number of plasma cells, which positively affects local immune defense.
For correction by nanocobalt and probiotic, there were no probable changes in the intensity of the LPO processes in terms of the level of production of its products (TBC-active products and DK) in plasma, as well as the activity of catalase and total AOA, and no statistically significant deviations in glucose, uric acid and creatinine, as well as activity of AsAT, AlAT and LF, indicating no negative effect on detoxification functions of the liver and kidney of the laying hens. However, an increase in the number of erythrocytes was detected by 17.6 % (p < 0.05), hemoglobin content was 22.9 % (p < 0.01) and total protein by 7.4 % (p < 0.05).
