Long-term effects of high-energy, low-fishmeal feeds on growth and flesh characteristics of Atlantic salmon (Salmo salar L.)

Long-term effects of feeding high-energy, low-fishmeal feeds on growth and flesh characteristics were investigated in ~ 1–4.5 kg Atlantic salmon (Salmo salar). Feeds were a high-fishmeal control (HFM; 20% fishmeal of total feed ingredients), medium-fishmeal (MFM; 15%), and low-fishmeal (LFM; 10%). Growth and feed utilisation were assessed regularly over a 9 month growth trial, and flesh characteristics (fillet fat, pigment concentration, visual colour) were monitored at ~ 1 kg weight intervals. These were expanded to include instrumental colour and texture analyses and sensory evaluation in harvest-size (ca. 4.5 kg) salmon. There were no significant differences between feed treatments with respect to growth, feed utilisation, mortality and flesh characteristics; confirmed by a lack of cluster formation in a multivariate principal component analysis (PCA). The most pronounced correlations were found between flesh pigment and a*-value, SalmoFan, hue and intensity, between muscle fat and pigment, and between fat and sensory attributes (odour, taste, flavour, texture and colour). This study demonstrates that dietary fishmeal levels can be substantially reduced from present commercial levels without compromising growth performance or flesh quality of harvest-size salmon.