Comparative effects of dietary different zinc forms on performance, immunity, and oxidative stress-related gene expression in Nile tilapia, Oreochromis niloticus

Abstract Zinc is one of the essential elements, which play an important role for fish performance, occurred naturally in different types of inorganic, nano-sized, organic, and elemental forms. Thus, the present study was carried out to assess the effects of Zn forms on the performance of Nile tilapia, Oreochromis niloticus (L.). Three isonitrogenous (30% crude protein) and isolipidic (7.0% lipids) diets were formulated containing biogenic zinc oxide nanoparticles (ZnO-NP), ZnO supported on kaolinite (ZnO-K), or mineral Zn form (ZnSO4) as a control diet. Fish (2.0–2.5 g) were fed on one of tested diets in triplicates up to apparent satiation four times a day for 12 weeks. Results showed that highest growth performance and feed intake were recorded in fish fed ZnO-K. However, this diet elevated villus width/length, absorption area, and goblet cells and significantly enhanced activities of intestinal digestive enzyme and cholecystokinin content. Comparing to the control diet, serum alanine and aspartate aminotransferases were significantly lower, while serum total protein, albumin, and globulin contents were obviously higher in fish fed ZnO-K containing diets. Additionally, significant higher values of total antioxidant capacity, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) activity accompanied with lower value of malondialdehyde (MDA) were observed in fish fed ZnO-K in diets. The expression of SOD, CAT, and IgM-2 genes were significantly up-regulated in the liver of fish fed a diet containing ZnO-K compared with other Zn forms. Results obtained herein indicated that the ZnO-K was the optimum Zn form followed by biogenic ZnO-NP to enhance growth performance, health, immunity, and oxidative stress biomarkers of Nile tilapia. Statement The authors stat that their individual contribution is equal.