Growth of mediterranean yellowtail (Seriola dumerilii) fed extruded diets containing different levels of protein and lipid

Abstract

Young Mediterranean yellowtail were maintained for 10 months in three different weight groups (114, 141 and 192 g initial mean liveweight) and fed four extruded diets containing two protein levels (45 and 50% CP) and two lipid levels (14 and 17%) according to a factorial design. Survival at the end of trial was around 70% and was unaffected by treatment. Final mean liveweights were 1044, 1098, 1336 and 1163 g for groups fed 45/14, 45/17, 50/14 and 50/17 protein/lipid diets, respectively. The effect of lipid level was not significant, but the growth of fish fed diets containing 50% CP was higher than those fed the 45% CP diets. Nutritive parameters such as, feed intake, feed conversion ratio and PER were not affected by diets. Body composition and nutrient retention values were similar for fish fed various diets. Viscerosomatic index was higher for fish fed diets containing 17% lipid and hepatosomatic index was higher for those fed 50% CP or 12% lipid. Dressout percentage was higher for fish fed diets containing 50% CP.