The Effect of Feeding Varying Levels of Soybean Meal in High‐Nutrient‐Density Diets on Growth Performance and Body Composition of Juvenile Atlantic Salmon

Abstract

AbstractSix experimental, high‐nutrient‐density (HND) diets containing practical ingredients (55% protein, 20% lipid) were fed to juvenile (initial weight [mean ± SE] = 27.6 ± 1.0 g) Atlantic salmon Salmo salar reared in freshwater for 12 weeks. The control diet was the open‐formula Atlantic salmon diet MNR‐98HS, which contained 0% soybean meal (SBM) and 30% fish meal (FM). Four experimental diets had 30% FM and soybean levels from 5% to 30%. Two additional diets contained a reduced level of FM (24%) and either 20% or 30% SBM. Weight gain (specific growth rate [SGR]), feed conversion ratio (FCR), protein efficiency ratio (PER), condition factor, trypsin activity, body composition, and hepatosomatic index were determined. No differences in SGR (1.88–1.94), FCR (0.78–0.82), PER (2.20–2.32), or trypsin activity were observed between treatments and the control diet. A negative linear response was observed between SBM content and either body lipid or fecal dry matter. Fish whole‐body lipids decreased linearly from 22.0% to 12.9% between control and 30% SBM dietary groups. Results suggest that the use of HND diets may contribute to protein‐sparing functions of Atlantic salmon by SBM carbohydrates; however, SBM inclusion may induce changes along metabolic pathways into muscle tissue.