Zinc is one of the essential elements, which plays an important role for fish performance. It occurs naturally in
different types of inorganic, nano-sized, organic, and elemental forms. Thus, the present study was carried out to
assess the effects of dietary 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 the tested diets in triplicates up to apparent satiation four times a day for
12 weeks. Results showed that the 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 |
