Alteration of haematological and antioxidant parameters in common carp ( <i>Cyprinus carpio</i> ) fed olive ( <i>Olea europea</i> ) leaf extract after exposure to Danitol ^®

Abstract

The present study aimed to assess the benefits of dietary olive (Olea europea) leaf extract (OLE) on haematological, biochemical and antioxidant parameters in the blood and livers of common carp (Cyprinus carpio) exposed to the pesticide Danitol®. Four treatments were carried out: (a) fish fed the control diet for 37 days (control); (b) fish fed the control diet for 30 days, followed by 7 days of exposure to 0.05 mg/L Danitol®; (c) fish fed the E1 diet for 30 days, followed by 7 days of exposure to 0.05 mg/L Danitol® (1 g/kg OLE); and (d) fish fed the E2 diet for 30 days, followed by seven days of exposure to 0.05 mg/L Danitol® (2 g/kg OLE). Exposure to Danitol® significantly decreased red blood count (RBC), haematocrit, haemoglobin, plasma and hepatic catalase (CAT), and superoxide dismutase (SOD) activities. However, the pesticide increased plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and plasma and hepatic malondialdehyde (MDA) contents. The RBC showed lower resistance against hypotonic osmotic shock, as established by the osmotic fragility test. OLE administration restored the changes caused by Danitol®, of which the most pronounced effects were observed in the fish fed 2 g/kg OLE. We may conclude that Danitol® exposure causes oxidative stress, yet provide protection against numerous adverse effects through the supplementation of olive oil extract (OLE), resulting in a higher red blood cell count.