Nano-zinc particles was synthesized using the Bacillus subtilis and the particles were characterized by trans- mission electron microscopy (TEM) methods. Treatment was applied in a completely randomized design with three sources of zinc (zinc sulfate, organic zinc, and nano-bio zinc) along with a control diet nonsupplemented with zinc, resulting in a total of 4 treatments with 6 replicates of 10 chicks. Performance criteria, ileum morphometry and microbial population and jejunum tight junction proteins relative expression were evaluated during the trial. The particle size of the synthesized zinc nanoparticles ranges 80 to 350 nm, with crystalline spherical or roughly spherical forms. Inclusion of nano-bio zinc increased BW and improved FCR compared to the organic and ZnSO4. Zinc supplementation meaningfully (P< 0.01) changed ileum morphology and reduced ileum microbiota compared to non-supplemented control group. Relative length of duodenum, jejunum and ileum and relative weight of liver and bursa of Fabricius were reduced (P< 0.01), but relative weight of carcass, breast and thigh were increased by supplementation of zinc on d 42. Supplementation of zinc increased (P<0.01) the relative expression of claudin-1, occludin and zonula occluden-1 and reduced (P<0.01) claudin-5 and zonula occluden-2 on day 28. Claudin-1, claudin-5, occludin and zonula occluden-1 expression were higher (P< 0.01) in chicks fed organic and nano-bio zinc compared to the chicks fed ZnSO4 on d 42. Taken together, the results indicated that the biosynthesis of zinc bio-nanoparticles using Bacillus subtilis for poultry is feasible. Furthermore, the data reported herein demonstrated that nano-bio zinc can effectively improve performance, intestinal health and integrity.
