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This study investigated the protective effect of dietary cinnamon (Cinnamomum zeylanicum) powder (CzP) on the growth performance, haemato-biochemical, innate immunity, and hepatic antioxidant indices of tilapia (Oreochromis niloticus) fingerlings against the toxic effect of prolonged lead (Pb) exposure. Fish (22.6–25.3 g) were fed on diets supplied with two CzP levels (0.0 (control) and 10 g/kg diet) up to satiety for 60 days. At each CzP level, fish were exposed to 0.0 and 7.94 mg Pb/L in five replicates. At the end of this trial, Pb residues in the whole-fish body as well as haemato-biochemical, antioxidant, and immune indices were determined. The waterborne Pb adversely affected the growth performance, white blood cells and red blood cells counts, hematocrit, and hemoglobin levels. Blood cortisol, glucose, total cholesterol, serum alanine and aspartate aminotransferases and lactate dehydrogenase values were significantly higher; meanwhile, total lipids, total protein, albumin, and globulin as well as alkaline phosphatase were significantly lower in Pb-exposed fish. Hepatic oxidative stress biomarkers (malondialdehyde, superoxide dismutase, catalase, and total antioxidant activity) and serum immune indices (respiratory burst activity, serum lysozyme activity, and total immunoglobulins) were progressively suppressed by Pb exposure. On the other hand, the dietary supplementation of cinnamon powder alone significantly enhanced the growth, hemato-biochemical, antioxidant, and immune indices of Nile tilapia. Additionally, dietary CzP significantly mitigated Pb-induced effects in regard to the above-mentioned variables. Exposing Nile tilapia to Pb toxicity induced significant Pb accumulations in the whole-fish body; meanwhile the dietary CzP effectively reduced the Pb accumulation in the body of Pb-exposed fish. Thus, the dietary CzP had several encouraging effects on growth, antioxidant, and immune indices of Nile tilapia. Feeding the Pb-exposed fish with CzP effectively reduced the Pb accumulation in the fish body and offered direct protection against Pb-induced oxidative stress. The findings of the present study suggest that dietary cinnamon can be used as an immune-stimulant for mitigating the effects of heavy metals toxicity in Nile tilapia aquaculture. |
