Differences in performance, flesh composition and water output quality in relation to density and feeding levels in rainbow trout, Oncorhynchus mykiss (Walbaum), farming

Abstract. The aim of this research was lo evaluate the effect of density and feeding level (initially 8 or 16kg/m³ and 1·3% or 2% of present biomass respectively) on productive traits, meat composition and water quality output in farmed rainbow trout, Oncorhynchus mykiss (Walbaum). Individual fish growth shows significant differences in relation to density and feeding level; feed conversion rate is positively Influenced by the lower feeding level and low rearing density. At low density, specific growth rate, protein efficiency ratio and coefficient of variation of individual final weights are more favourable than at high density. Dry matter and lipid composition of meat are positively affected by feeding level; whereas no differences are recorded on the amino acid and fatty acid profiles. Water quality shows differences due to density (NO₃ and NH₄⁺) and feeding level (NO₂, NH₄⁺ and P).