Effects of Different Lipid Sources on Growth and Fatty Acid Composition of Juvenile Triangular Bream Megalobrama terminalis

Abstract

AbstractFive diets containing lipids from different sources, namely fish oil (FO), soybean oil (SO), linseed oil (LO), rapeseed (canola) oil (RO), and palm oil (PO), were fed to juvenile Triangular Bream Megalobrama terminalis (initially weight, 1.20 ± 0.02 g) for 70 d. At the end of the feeding trial, weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), and daily feed intake (DFI) were not significantly different among all treatments. The retention rates of C22:6(n‐3) (docosahexaenoic acid [DHA]) in fish fed LO‐based (143.8%) diets were significantly higher than in those fed FO‐based (61.0%) diet. Moreover, fish fed LO‐based diet showed a significantly higher C20:5(n‐3) (eicosapentaenoic acid [EPA]) content (1.6%) in the liver than fish fed SO‐, RO‐, and PO‐based (1.1, 0.9, and 0.9%, respectively) diets. The retention rates of C20:4(n‐6) (arachidonic acid [ARA]) in fish fed RO‐based (341.3%) diets were significantly higher than in those fed FO‐, LO‐, and PO‐based (87.3, 176.8, and 216.3%, respectively) diets, while fish fed SO‐ and RO‐based diets had significantly higher ARA concentrations in the liver than did fish fed FO‐based diet. The fatty acid compositions of fish tissues were significantly affected by different lipid sources. Fish fed vegetable oil (VO) diets had lower n‐3 long‐chain polyunsaturated fatty acid (LC‐PUFAs) concentrations in dorsal muscles than did fish in the FO group (18.4%), and significant differences were detected in fish fed SO (10.1%) and RO (10.9%) diets. These results showed that Triangular Bream have an ability to synthesize DHA, EPA, and ARA from alpha‐linolenic acid (ALA) and linoleic acid (LA). However, fish fed VO‐based diets could reduce the nutritional value of the fish flesh.