Antioxidant vitamins, minerals and lipid levels in diets for Atlantic salmon (Salmo salar, L.):: effects on growth performance and fillet quality

An experiment with 2((7 - 3)) reduced factorial design was conducted to study the biological effects of pro- and antioxidant micronutrients and lipid in Atlantic salmon. Vitamins C and E, astaxanthin, lipid, iron, copper and manganese were supplemented at high and low levels. For vitamins and minerals, high levels were chosen to be below the anticipated toxic level and the low levels were just above the requirement (vitamin C, 30 and 1000 mg kg(-1); vitamin E, 70 and 430 mg kg(-1); Fe, 70 and 1200 mg kg(-1); Cu, 8 and 110 mg kg(-1); Mn, 12 and 200 mg kg(-1)). For astaxanthin, the dietary levels were 10 and 50 mg kg(-1) and for lipid, 150 and 330 g kg(-1). The experiment was started with postsmolts (148 +/- 17 g) and lasted for 5 months. The variation in micronutrients had only minor effects on growth, feed conversion and fillet quality, measured as lipid and astaxanthin deposition. High dietary lipid had a profound positive effect on growth and feed conversion but gave fillets nearly two times the fat content that was found in fish fed the low lipid diet. Astaxanthin deposition in the fillet was primarily affected by dietary astaxanthin with a positive effect of high dietary lipid in week 14 but not in week 23. Vitamin E protected the fillet against iron ascorbate stimulated oxidation, with no effect of the other nutrient variables.