THE OPPOSING EFFECT OF ASCORBIC ACID (VITAMIN C) ON OCHRATOXIN TOXICITY IN NILE TILAPIA (Oreochromis niloticus)

The opposing effect of ascorbic acid against ochratoxin induced perturbations in some haematological and biochemical parameters in Nile tilapia (Oreochromis niloticus) was investigated. This study was carried out to evaluate the ability of a minimum level (500 mg/ kg diet) of vitamin C to counteract the toxicity of two levels of ochratoxin (400 and 600 μg/ kg diet). Nile tilapia (5060 g/ fish) was assigned to five treatments with three replicates each. The first treatment was fed normal diet and kept as control. The second and third ones were fed normal diet containing 400 and 600 μg of ochratoxin/kg diet, respectively. The fourth group was fed normal diet containing 400 ug of ochratoxin and 500 mg of vitamin C /kg diet. The fifth group was fed normal diet with 600 μg of ochratoxin and 500 mg of vitamin C/kg diet. The obtained results showed a significant decrease in erythrocyte count (RBCs), haemoglobin content (Hb) and haematocrit value (Hct) in fish exposed to the low or high level ochratoxin and the vitamin C enhanced the blood parameters in fish exposed to both levels of ochratoxin to values close to those of control fish. The high level of ochratoxin (600 μg/ kg diet) induced a significant decrease in mean corpuscular volume (MCV), mean corpuscular haemaglonin (MCH) and mean corpuscular haemaglonin concentrate (MCHC) blood indices. Moreover, the plasma total protein, total lipids and lactate dehyrogenase were decreased significantly in response to the two doses of ochratoxin. On other hand, the glucose concentration was increased significantly in fish fed the low or high level of ochratoxin, whereas the plasma glucose concentration, total lipids and lactate dehyrogenase in the fish group fed ochratoxin with vitamin C became similar to those of the control. The total protein content and the activity of aspartate aminotransferase (AST) in the liver and muscle were significantly decreased in fish fed on the two levels of ochrayoxin. On the other hand, the activity of alanine aminotransferase (ALT) in the liver and muscle was increased significantly in the fish group exposed to the high dose of ochratoxin. Vitamin C administration into the ochratoxin toxicated fish normalized the total protein content and AST activity to become similar to those of the control group.