Effects of Dietary Pro- and Antioxidants on Some Protective Mechanisms and Health Parameters in Atlantic Salmon

Abstract

Health aspects were investigated in postsmolt Atlantic salmon Salmo salar fed high (below known toxic limit) or low (above the minimum requirement) dietary levels of vitamin E, vitamin C, astaxanthin, total lipid, iron, copper, and manganese using a 2⁷⁻³ reduced factorial design. Hematocrit and hemoglobin were positively affected by iron after 14 and 23 weeks of feeding. Red blood cell count was not influenced by the dietary differences. Phagocytic chemiluminescent responses were positively affected by vitamin E after 14 and 23 weeks, but serum complement-mediated hemolysis and lysozyme activity in serum and in head kidney were unaffected. Some biological effects on endogenous antioxidants were positive effects of vitamin E on total superoxide dismutase activity in liver after 14 weeks and in muscle after 23 weeks, negative effects of astaxanthin on muscle catalase activity, and positive effects of dietary lipid on liver glutathione and total mercaptans after 23 weeks. None of the measured biological responses were affected dramatically by the dietary variables, indicating that the fish seem to tolerate a large range of dietary pro- and antioxidants under normal rearing conditions.