Linking the applied EWOS protein replacement program to the basic research in the Aquaculture Protein Centre

Soy has made a significant contribution to sustainable aquaculture by allowing fish meal replacement. However, high dietary levels of soy induce pathological changes in the hindgut of salmonids. This may also be problematic with other plant materials. Th e content of nutrients, structural compounds, and antinutritional factors (ANFs) vary among different soy products, and among different soy cultivars and crops. Thus, soy of different origin should impact the intestinal function in salmon differently. Thi s study will characterise and profile soy (and other plant) products of different origin in terms of composition and ANFs, and grade how they affect growth and digestive function, induce pathology in the intestine, and change the gut microflora in Atlanti c salmon. We will measure growth and digestibility of nutrient, enzyme activities in intestinal contents and tissues, bile salts in intestinal contents, pathology in the gastrointestinal tract (GIT), systemic and GIT immunologial responses, rate of tissu e regeneration (cell division) in the GIT, and changes in both the adherent and luminal intestinal microflora. Pathology and immunological responses of the GIT will be evaluated histologically and by histochemical colouring techniques. Cell division GIT tissue will be indicated by staining the proliferating cell nuclear antigen (PCNA) and quantified by image analysis. The definition soy and other plant proteins with low negative impact on the intestine will ameliorate negative effect associated with pla nt proteins in salmon feed. It will also increase the general understanding about effects of different vegetable components in salmon. This will reduce the dependence on marine feed ingredients and will contribute to increased profitability in the salmon industry.