Effects of broodstock dietary lipid on fatty acid compositions of eggs from sea bass ( Dicentrarchus labrax)

Abstract

Samples of sea bass ( Dicentrarchus labrax) eggs from broodstock which had been fed either a formulated pelleted feed, containing fish and corn oil, or a local trash fish, bogue ( Boops boops) were analysed for lipid class compositions, fatty acid compositions of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) and wax ester and fatty alcohol compositions of wax esters. The pelleted feed contained 1.3 mg g −1 of arachidonic acid (20:4n-6; AA) and an AA/eicosapentaenoic acid (20:5n-3; EPA) ratio of 0.1 while the trash fish contained 4.8 mg g −1 AA and an AA EPA ratio of 0.7. Docosahexaenoic acid (22:6n-3; DHA) concentrations were similar for both diets (about 23 mg g −1). The fatty acid compositions of PC, PE and PI from eggs of fish fed trash fish contained significantly more AA, 22:5n-6 and DHA compared to fish fed the pelleted feed. The AA EPA ratios in these phospholipids were around five-fold higher in the trash fish-fed group compared to those fed the fish and corn oil containing diet. In PI, which contains characteristically high levels of AA, the AA EPA ratios were 1.5 and 8.6 for eggs derived from broodstock fed the pelleted diet and the trash fish, respectively. Determination of lipid class compositions of sea bass eggs revealed the presence of high levels of wax esters which were previously unrecorded in this species. The use of broodstock diets containing blends of corn oil and Northern hemisphere fish oils may be undesirable in that they contain high levels of 18:2n-6 and have low ratios of DHA EPA and of AA EPA . In an effort to improve egg quality and larval viability, efforts should be directed towards establishing the best ratio of DHA/EPA/AA in formulated feeds such that requirements for neural function and visual performance are maximised and that production and efficacy of eicosanoids are adequate to permit physiological functions to operate efficiently.