Effects of dietary inclusion of Antarctic krill (Euphausia superba) meal in low fishmeal diets on Atlantic salmon (Salmo salar L.) growth, nutrient utilization, fillet quality, and wound healing capacity

Ecological and economic concerns of fishmeal and terrestrial crop contributions to protein and lipid in the diets of cultured fish have resulted in significant reductions over the last few decades, initiating investigations into alternative sources. Marine zooplankton, such as Antarctic krill possess high levels of protein, phospholipid, essential n-3 LC-PUFA (EPA and DHA) as well as carotenoids like astaxanthin. Salmon were fed experimental diets containing 0, 8 and 12 % Antarctic krill meal (KM) over a 25-week period and quantified various production characteristics of the fish as well as their responses to mechanical wounding. Atlantic salmon gained over 300 % of their initial body weight over the 25-week feeding period and their Condition Factor, FCR, PER, diet digestibility and whole-body composition of fish receiving the 8 and 12 % KM test diets did not significantly differ from the 0 % control diet. However, fish fed KM test diets were able to maintain the high performance of the control diet fed fish, but with up to 31 % lower plant proteins, 15 % less micronutrient additives, 14 % lower lipid supplements, and 4 % less synthetic astaxanthin due to KM meal. In addition, salmon fillets showed a significantly higher mean level of pigmentation (i.e., yellow and red colouration) in fish fed the 12 % KM meal diet, and gross imaging showed wounded skin from fish fed 12 % KM had significantly less variation in colouration/appearance from unwounded skin, compared to control, which could be beneficial to the Atlantic salmon industry by reducing hyperpigmentation that often leads to costly downgrades for producers. • Krill meal could replace/ reduce the use of conventional plant-proteins with better protein utilization. • Inclusion of krill meal enhanced pigmentation of the Atlantic salmon fillet. • Krill meal in the diet positively impacted wound healing processes through pathways regulated by Akt and TGFβ. • Benefits of these diets to Atlantic salmon aquaculture exist as hyperpigmented fillets cause significant losses for producers.