The effect of feed pigment type on flesh pigment deposition and colour in farmed Atlantic salmon, Salmo salar L.

The characteristic pink colour of salmonid flesh is a result of deposition of naturally occurring carotenoid pigments. Achieving successful pigmentation in farmed salmonids is a vital aspect of fish farming and commercial feed production. Currently commercial diets for farmed salmonids contain either or both of the synthetic pigments commercially available, astaxanthin and canthaxanthin. Atlantic salmon, Salmo salar L. ( = 220 g initial weight) were given feeds where the pigment source was astaxanthin only, canthaxanthin only or a astaxanthin/canthaxanthin mix. The rearing environment was 12 x 3 m tanks supplied with sea water at the EWOS research farm Lonningdal, near Bergen, Norway. As the proportion of dietary canthaxanthin increased, flesh pigment levels also showed an increase; the pigment content in the muscle of canthaxanthin-only fed fish was 0.4 mg kg(-1) (or 14%) higher than that of the astaxanthin-only fed fish, with the mixed pigment fed fish being intermediate between the two extremes. Results of cross-section assessment for Minolta colorimeter redness (a*) values and Roche Salmofan(TM) scores also showed an increase in colour with increasing proportions of canthaxanthin in the feed. The data reported clearly indicates that S. salar ( = 810 g final weight) of this size deposit canthaxanthin more efficiently than they do astaxanthin. These results contrast with those obtained by other authors with rainbow trout, Oncorynchus mykiss (Walbaum), and imply that the absorption or utilization of the pigments differs between species.