Effects of Activated Charcoal on Growth, Immunity, Oxidative Stress Markers, and Physiological Responses of Nile Tilapia Exposed to Sub-Lethal Imidacloprid Toxicity

Abstract

The existing study was designed to assess the influences of dietary activated charcoal (AC) on the growth performance, immune responses, antioxidative status, and its mitigating roles against the physiological responses of Nile tilapia exposed a sub-lethal dose of a neonicotinoid agriculture pesticide, namely, as imidacloprid (IMID). Nile tilapia juveniles were fed on diets supplemented with graded AC levels as 0 (control), 5, 10, 15, and 20 g/kg diet for eight weeks. Growth, hemato-biochemical indices, and antioxidant and immune responses of fish in all groups were evaluated at the end of the feeding experiment. Afterward, fish in all experimental groups were subjected to a sub-lethal dose of IMID (0.0109 μg/L) for two weeks. Then, fish mortalities, stress indicators, and IMID residual levels in liver and flesh were examined. Results of the feeding experiment showed that total feed intake, weight gain, final body weights, and feed efficiency ratio were significantly increased in all AC groups compared with the control group. The survival rate was 100% in all experimental groups. No statistical differences were observed in the hematological picture of all experimental groups except the lymphocyte count, which was significantly increased in all AC groups compared to the control group. Total protein, albumin, globulin, nitric oxide levels, lysozyme, and respiratory burst activities were significantly increased in all AC groups. Serum alanine transaminase, aspartate transaminase, alkaline phosphatase activities, and malondialdehyde (MDA) levels were significantly decreased in all AC groups compared with the AC0 group. After exposure to a sub-lethal dose of IMID, survival rates were significantly elevated, and IMID residual levels in liver and flesh were significantly decreased in all AC groups than in the control group. Moreover, second-order polynomial regression showed that dietary supplementation with 14.30 g AC/kg diet resulted in the lowest blood glucose and serum MDA levels. Conclusively, we suggest dietary supplementation with 14.30 g AC/kg diet to modulate physiological responses of Nile tilapia to sub-lethal IMID toxicity.

Keywords: Oreochromis niloticus; antioxidant; hematology; lysozyme; nitric oxide.

Figure 1

Serum lysozyme (LYZ) activity (A) and Nitro blue tetrazolium (NBT) levels (B) of Nile tilapia fed diets supplemented with graded, activated charcoal (AC) levels for 8 weeks. (a, b, c) indicate significant differences between groups.

Figure 2

Serum malondialdehyde (MDA) (A) and nitric oxide (NO) levels (B) of Nile tilapia fed diets supplemented with graded, activated charcoal (AC) levels for 8 weeks. (a, b, c) indicate significant differences between groups.

Figure 3

Residual imidacloprid (IMID) levels in the flesh (A) and liver (B) of Nile tilapia fed on diets supplemented with graded, activated charcoal (AC) levels for 2 months and then exposed to a sub-lethal IMID level for 2 weeks. (a, b, c, d) indicate significant differences between groups.

Figure 4

Second-order polynomial regression equation between blood glucose levels of Nile tilapia fed different dietary activated charcoal (AC) levels for 8 weeks and then exposed to a sub-lethal imidacloprid (IMID) level for 2 weeks. Values expressed as means ± S.E.M.

Figure 5

Second-order polynomial regression equation between malondialdehyde (MDA) levels of Nile tilapia fed different dietary activated charcoal (AC) levels for 8 weeks and then exposed to a sub-lethal imidacloprid (IMID) level for 2 weeks. Values expressed as means ± S.E.M.