2.1. Feed ingredients and diet production
Four different diets (Table 1) that contained soybean meal (SBM), rapeseed meal (RSM), pea meal (PM) or faba bean meal (FBM) were produced at the Center for Feed Technology at the Norwegian University of Life Sciences (Ås, Norway). All diets were formulated to have similar level of starch and lipids, and contain macro nutrients at levels recommended for commercial feeding for salmonids. Fish meal was the major ingredient in the diets. In the diets with protein-rich plant ingredients, SBM and RSM, whole wheat was included as a source of starch at levels to reach a SBM:wheat and RSM:wheat ratio of 2:1. This ratio is similar to that used by Denstadli et al. (2006) with similar pretreatment system, however the ratio led to different crude protein and dietary fibre levels. For the two diets with starch-rich plant ingredients, PM and FBM, no additional starch was added.