Effects of dietary selenium on the pathological changes and oxidative stress in loach (Paramisgurnus dabryanus)

In this study, loach (Paramisgurnus dabryanus) were fed artificial diets containing 0.31 (control), 0.39, 0.48, 0.50 and 0.62 mg kg(-1) of selenium (Se) for 60 days, respectively. Liver histopathology, hepatocyte ultrastructure, blood indices, biochemical parameters of liver functions and oxidative stress in the Se-treated loach were then assayed. The results showed the following: histopathological and ultrastructural lesions in liver were only observed in loach fed the 0.62 mg Se kg(-1) diet; Haemoglobin and total protein were significantly increased in the 0.50 mg Se kg(-1) group; albumin and high-density lipoprotein were increased significantly in the 0.48-0.50 mg Se kg(-1) groups. However, white blood cell count was significantly decreased in the 0.48 mg Se kg(-1) group; alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were decreased in the 0.39-0.50 mg Se kg(-1) groups. In liver tissue, the content of hydrogen peroxide was lower than that of controls in the 0.48-0.50 mg Se kg(-1) groups, and the malondialdehyde level was lowest in the 0.48 mg Se kg(-1) group. The activities of superoxide dismutase and glutathione peroxidase were significantly increased in the 0.50 mg Se kg(-1) group; catalase and total antioxidant capacity were markedly increased in the 0.48-0.50 mg Se kg(-1) group. These present results indicated that the dietary Se requirement for loach is 0.48-0.50 mg Se kg(-1) diet.