Influence of dietary lipids on survival, growth, and fatty acid composition of brown trout and Atlantic salmon juveniles

Two subsequent experiments were conducted to evaluate the effect of dietary lipids on survival, growth, and fatty acid composition of brown trout and Atlantic salmon. Fish (average individual mass, 0.09 and 0.20 g, for brown trout and Atlantic salmon, respectively) were fed, in triplicate tanks, four experimental diets containing 14% lipids with different fatty acid composition: diet 1, contained oleic acid (deficient essential fatty acids diet); diet 2, contained linseed oil and provided linoleic (18:2n-6) and linolenic (18:3n-3) acids; diet 3, contained cod liver oil and provided all polyunsaturated fatty acids; and diet 4, contained lecithin which provided 18:2n-6 in the form of phospholipids. After 8 weeks, survival and growth of brown trout were not significantly different among dietary treatments. In contrast, growth of Atlantic salmon differed significantly and after 6 weeks. Fish fed diet 1 (average individual mass 0.37 g) grew significantly less than those fed diets 3 and 4 (average individual mass 0.69 and 0.68 g, respectively). Survival of Atlantic salmon was poor (average 45.1%), and did not significantly differ among dietary treatments. Fatty acid composition of whole body lipids are currently being analyzed and will be presented.