Effects of dietary Antarctic krill Euphausia superba meal on growth performance and muscle quality of triploid rainbow trout Oncorhynchus mykiss farmed in sea water

The present study was conducted to investigate the effects of replacement of dietary fish meal by Antarctic krill Euphausia superba meal on growth performance, body composition and organoleptic quality of triploid rainbow trout Oncorhynchus mykiss (initial body weight 102.06 +/- 0.04 g) farmed in sea water. The basal diet contained 51% of fish meal. Based on it, five isonitrogenous and isolipidic experimental diets were formulated with the protein replacement ratio of fish meal by krill meal as 0, 15%, 30%, 60% and 100%, respectively (DM0, DM15, DM30, DM60 and DM100, respectively). After an 8-week feeding trial, results showed that increasing levels of dietary krill meal linearly and quadratically increased significantly FBW, SGR and FI (P < 0.05). Significant positive linear trends were found between the increasing levels of dietary krill meal and carotenoid concentrations, redness (a*), yellowness (b*) and chroma (C*) in muscle; and significant negative trends were found in the lightness (L*) and hue (H*) responses (P < 0.05). The pH and liquid holding capacity (LHC) were not affected by dietary krill meal levels (P > 0.05). A positive quadratic trend was found between the dietary krill meal level and the springiness, and a negative linear trend in cohesiveness occurred (P < 0.05). The content of fluorine in vertebra increased linearly and quadratically significantly (P < 0.05) but the content of fluorine in muscle was not significantly affected by increasing levels of dietary krill meal (P > 0.05). The highest fluorine content in muscle was within the safe edible limit for humans. These results suggested that Antarctic krill meal could improve the growth performance and muscle pigmentation of triploid rainbow trout farmed in seawater.