Replacement of fish meal with rapeseed protein concentrate in diets fed to turbot (Psetta maxima L.)

Replacement of fish meal with rapeseed protein concentrate in diets fed to turbot (Psetta maxima L.) The potential of rapeseed protein concentrate as fish meal alternative in diets for juvenile turbot was evaluated. Triplicate groups of fish were fed isonitrogenous (58.1 +/- 0.9% CP) experimental diets with equal gross energy content (21.5 +/- 0.3 MJ kg(-1)) where 0, 33 and 66% (designated as R0, R33 or R66, respectively) of fish meal was replaced with rapeseed protein concentrate. At the end of the feeding period (84 days), fish fed diet RO or R33 showed significantly higher weight gain and feed intake than fish fed diet R66. It is assumed, that reduced feed intake and growth in fish fed diet R66 can mostly be attributed to negative effects on diet taste resulting from the glucosinolate content of rapeseed protein concentrate. The control diet gave significantly better feed efficiencies than diets R33 and R66. This was probably due to lower protein, amino acid and phosphorus availability in diets R33 and R66.