Effects of dietary fat levels on growth, feed efficiency and biochemical compositions of Eurasian perch Perca fluviatilis

Abstract

A feeding experiment was conducted for 10 weeks with Eurasian perchPerca fluviatilis juveniles (33.1–35.9ginitial body weight) using three dietary fat levels (11.7, 15 and 19.3%). Theresults showed that increasing dietary fat content increased growth, feedefficiency and protein utilization of perch (P < 0.05) but did not affectmortality. Lipid analysis showed that the composition of some perch tissueswerealso significantly affected by increasing dietary fat content, with an increaseof lipid deposition in the viscera (from 64.9% in fish fed 11.7 % fat to 78.8%in fish fed 19.3% fat) and liver (from 12.4 to 23.8%) (P < 0.05), while themuscle composition was not affected by the dietary treament. Highdocosahexaenoic acid (22:6n-3, DHA) and high docosahexaenoicacid/eicosapentoenoic acid (20:5n-3, EPA) ratios were found in the liver andmuscle lipids as compared to the dietary fatty acid compositions, suggestingthat Eurasian perch might possess a high capability of converting the longchainhighly unsaturated fatty acids, especially DHA from its dietary precursors.