Replacement of LT fish meal with a mixture of partially deshelled krill meal and pea protein concentrates in diets for Atlantic salmon (Salmo salar)

The aim of the study was to investigate how the replacement of LT-fish meal by a 3.5:1 mixture of an experimentally produced partially deshelled krill meal (PDKM) and a pea protein concentrate (PPC) affected growth rate, digestibility of main nutrients and minerals, fluoride accumulation and histology in Atlantic salmon (Salmo salar). Five extruded diets were fed to salmon with an average weight of 546 g, distributed into 15 tanks equipped with flow through sea water. During extrusion, increased krill meal resulted in increased lipid content in the feed mash and subsequently decreased pellet expansion and decreased pellet water stability. The salmon had an optimum growth rate with a PDKM/PPC inclusion of 400 g kg− 1. Starch digestibility decreased and lipid digestibility increased with increasing PDKM/PPC inclusion. Fluoride in faeces increased linearly with increasing dietary fluoride levels. Plasma cholesterol decreased with increased PDKM/PPC inclusion, whereas no major differences were seen for triglycerides, free fatty acids, glucose, or bile acids. Fish fed increased dietary PDKM/PPC showed an increased prevalence of mild to moderate nephrosis.