Changes in fatty acid profile and chemical composition of meagre (Argyrosomus regius) fed with different lipid and selenium levels

This study aimed to evaluate changes in body composition, specially muscle and liver fatty acid profile in meagre (Argyrosomus regius) fed with different dietary lipid sources and levels, with or without selenium supplementation. Six hundred meagre were fed twice a day, 6 days per week, with eight experimental diets for 60 days. Diets were a combination of fish oil or a vegetable blend (45% linseed + 35% rapeseed + 20% soybean oil), at 12 or 17% of oil and 0 or 1 mg/kg of organic selenium, in a 2 × 2 × 2 factorial design. The whole body protein and lipid content were affected by the dietary oil source. Fish oil diets increased long-chain (LC) PUFAs content in the edible tissues, while vegetable oil-based diets increased short-chain (SC) PUFAs. Vegetable oil diet tended to decrease the fish protein content. A higher lipid liver content was observed in meagre fed the vegetable oil blend. The results also suggested the ability of meagre to convert SC-PUFA to LC-PUFA when the vegetable oil is included in their diet. The possibility for partial substitution of fish oil by vegetable oil in meagre diets, resulting in lower dependence of fish oil in meagre farming, is also demonstrated here. Practical applications: The growing importance of aquaculture for basic food supply, and the urge for cost-effective and sustainable feeds that maintain or even increase fish quality, makes the search for alternatives to common feeds a route of upmost importance, as the vegetable oil here addressed. SC-PUFA and LC-PUFA contents of the studied tissues increased with diets supplemented with 17% oil level, which may ultimately add more value to this farmed species. These results indicate the possibility of the partial substitution of fish oil by vegetable oil in meagre diets, resulting in lower dependence on fish oil for fish farming. Meagre were fed with different dietary lipid sources and levels, with or without selenium supplementation, in a total of eight experimental diets during 60 days, in a 2 × 2 × 2 factorial design. Fish oil diet increases HUFAs and vegetable oil diet increases PUFAs in body composition. There is great potential for partial substitution of fish oil by vegetable oil in meagre (Argyrosomus regius) diets, resulting in lower dependence of fish oil in meagre farming. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This study had the support of the Fundação para a Ciência e a Tecnologia (FCT) Strategic Project UID/MAR/04292/2013 granted to MARE, and was partially supported by the European Regional Development Fund (ERDF) through the COMPETE—Operational Competitiveness Programme and national funds through FCT—Foundation for Science and Technology, under the project “PEst‐C/MAR/LA0015/2013. Tiago Simões and Luana Granada wish to acknowledge the financial support given by FCT (SFRH/BD/98266/2013 and SFRH/BD/102036/2014, respectively). Sthelio Braga wishes to acknowledge the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the financial support given (Process nº 0277‐13‐4).