Dietary starch, non-starch polysaccharides and their interactions affect nutrient digestibility, faecal waste production and characteristics differentially in three salmonids: Rainbow trout, Atlantic salmon and Arctic charr

Summary

Waste management has emerged as a critical issue in aquaculture. In this study, we examined the impact of dietary starch and non-starch polysaccharides (NSP) content on nutrient digestibility, faecal waste production, faecal removal efficiency and the faecal characteristics in three salmonid species, namely rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar) and Arctic charr (Salvelinus alpinus). Four diets were formulated according to a 2 × 2 factorial design. The first factor, starch, was tested by including 0% gelatinised wheat flour (low starch) or 20% gelatinised wheat flour (high starch) in a plant-based basal diet. The second factor, NSP, was tested by adding 0% NSP source (low NSP) or 10% NSP source (high NSP). High NSP level was achieved by adding an equal mixture of soya hull (5%) and wheat bran (5%). Diets were tested in triplicates for each species and feeding was done restrictively. Experimental duration was 42 days for rainbow trout and Atlantic salmon and 49 days for Arctic charr