Dietary protein requirement for young turbot (Scophthalmus maximus L.)

This study was conducted to determine the optimum dietary protein level for young (an initial weight of 89 g) turbot, Scophthalmus maximus L. Duplicate groups of the fish were fed the five isoenergetic diets containing the various protein levels ranging from 290 to 570 g kg−1 diet for 45 days. Survival was not affected by dietary protein level. Weight gain and feed efficiency were improved with dietary protein level up to 490 g kg−1 diet. Dietary protein requirement of young turbot using the broken-line model was estimated to be 494 g kg−1 diet based on weight gain response. Protein efficiency ratio was not influenced by dietary protein level. The highest protein retention was obtained from the fish fed the 490 g protein kg−1 diet. Proximate composition of the fish was not significantly affected by dietary protein level. In considering these results, it was concluded that the 494 g protein kg−1 diet with 100 g lipid kg−1 diet (15 MJ kg−1 diet) provided optimal growth of young turbot under these experimental conditions.