DIETARY LYSINE REQUIREMENT OF JUVENILE EURASIAN PERCH (Perca fluviatalis)

The aim of this study was to estimate the optimum dietary lysine requirement of juvenile Eura-sian perch (Perca fluviatalis), and to investigate the influence of different dietary lysine levels on growth, carcass composition, somatic indices and haematocrit value. A total of 240 juvenile perch was included in a 12-week feeding study. Based on the whole body amino acid profile of in total 48 perch of three different weight groups, eight semi-purified diets containing graded levels of lysine (L1-L8) were produced. The diets contained approximately 12% crude lipid and 40% crude protein and the lysine level varied from 12.2 (L1) to 24.3 (L8) g kg-1 dry matter (DM). Approximately 40% of the total nitrogen content in the diets was in the form of protein-bound amino acids. The ideal protein concept was applied for estimation of the amino acid re-quirements. Fish fed diets L5-L8 (18.3-24.3 g lysine kg-1 DM) had higher final body weight, weight gain, protein gain and specific growth rate (P