Influence of dietary phospholipid on early development and performance of Atlantic salmon (Salmo salar)

The present study aimed to confirm the requirement for dietary phospholipid in Atlantic salmon and better define the level and period of requirement. Thus, the effects of dietary supplementation with phospholipid supplied by krill or soy lecithinwere investigated in Atlantic salmon, Salmo salar. First feeding frywere fed diets containing 55% protein and 17% lipid supplementedwith krill oil or soybean lecithin in a regression design at five levels, 1.5 (unsupplemented), 2.6, 3.2, 3.6 and 4.2% total phospholipid and fish were sampled at 1 g (1400 degrees day postfertilisation, dpf), 2.5 g (1990 degrees dpf), 5 g (2350 degrees dpf), 10-20 g (2850 degrees dpf) and smolt (3800 degrees dpf). Survival was high overall with a positive correlation (r(2) = 0.59-0.72) between survival and dietary phospholipid supplementation. Growthwas improved by phospholipidwith highest growth achieved in fish fed krill phospholipid at 2.6% and in fish fed soy lecithin at 3.6%. The pattern of growth differed between fish up to 2.5 g and that from 2.5 g onwards with SGR (0-2.5 g) being significantly higher in fish fed 2.6% krill phospholipid and 3.6% soy phospholipid compared to the basal diet, whereas there was no difference in SGR (2.5 g-smolt) between the treatments. Intestinal steatosis was observed in 2.5 g fish fed the unsupplemented diet (20% prevalence) and lower levels of soy (10% prevalence), whereas it was absent from 2.5 g fish fed krill oil and higher levels of soy lecithin (>= 3.2%), and fish at all later stages. Prevalence of vertebral deformities was low but was reduced by increasing dietary phospholipid with krill oil generally being more effective. The results were consistent with salmon having a dietary requirement for dietary phospholipid in early life stages.

Statement of relevance: Determining the effects of dietary phospholipid level and source on growth, gut and skeletal health will help improve and optimise future diet formulations for early life stages (fry) of salmonids including, Atlantic salmon. (C) 2015 Elsevier B.V. All rights reserved.