Antioxidative and immunostimulatory effect of dietary cinnamon nanoparticles on the performance of Nile tilapia, Oreochromis niloticus (L.) and its susceptibility to hypoxia stress and Aeromonas hydrophila infection

An experiment was conducted to evaluate the effect of dietary cinnamon nanoparticles (CNP) on the growth performance, antioxidant and digestive enzymes activities, and innate immunity of Nile tilapia, Oreochromis niloticus (L.). Fish (9.7 +/- 0.3 g) were fed on diets enriched with 0.0, 0.25, 0.5, 1.0, 3.0, 5.0, and 10.0 g CNP/kg diet for 8 weeks. After the feeding trial, fish were challenged against hypoxia stress or pathogenic bacteria (Aeromonas hydrophila) infection. Fish performance was significantly improved with increasing CNP levels over the control diet. Furthermore, only crude protein contents in whole-fish body were significantly higher in CNP-fed fish than those fed the control diet. Antioxidant-stimulated activity was observed with dietary CNP where malondialdehyde (MDA) level and activities of superoxide dismutase (SOD) and catalase (CAT) increased significantly, whereas glutathione peroxidase (GPx) activity decreased significantly in CNP-fed fish. Likewise, CNP supplementation induced the secretion of protease, lipase, and amylase, which were maximized at 3.0-10.0 g CNP/kg diet. All innate immunity variables i.e. nitrous oxide (NO), nitro blue tetrazolium (NBT), and lysozyme activity were significantly higher in CNP-fed fish than the control one. No fish mortality was observed during hypoxia stress among all treatments, but CNP administration protected the fish against A. hydrophila infection. No mortality was observed in fish fed 3.0-10.0 g CNP/kg diet after bacterial challenge; meanwhile the mortality of fish fed the control diet was 66.7%. This study evoked that dietary CNP enhanced the performance, antioxidant and digestive enzymes activity, and innate immunity of Nile tilapia and its optimum level is 3.0 g CNP/kg diet.