Regulation of feed intake (FI) and lipid deposition in fish is of extreme relevance for aquaculture, either from economic, environmental and consumer perspectives. Indeed, feeding represents more than 50% of operating costs in intensive fish farming. Thus, reducing FI may have a high economic impact and also contribute to reducing the environmental impact associated with feeding. Further, reducing muscle lipid deposition will also have considerable implications on fillet quality to consumers.
Oleic acid (OA) is a monounsaturated long-chain fatty acid, highly present in several vegetable oils. In mammals, increasing OA intake has been linked to weight gain and lipid deposition control by interfering with FI (Hammad et al., 2016). Despite its interesting potential role, the potential use of OA as an additive in aquafeeds has been almost neglected until now, except for a recent study indicating that intraperitoneal administration of OA inhibited FI in rainbow trout (Librán-Pérez et al., 2014).
Thus, the aim of this study was to evaluate the effect of OA supplementation at different dietary lipid levels on appetite regulation and fatty acid-sensing mechanisms in European seabass (Dicentrarchus labrax). For that purpose, six isoproteic (45% crude protein) with two different dietary lipids levels (16 and 22%) were formulated with fishmeal and cod liver oil as protein and lipid sources and supplemented with 0, 1 or 2% of OA. Triplicate groups of European sea bass juveniles (21.4g) were fed with these diets. At the end of growth trial, final body weight, weight gain, and daily growth index were not affected either by dietary lipid level or OA supplementation. Diet supplementation with OA was associated with a reduction of FI without major impacts on the growth performance of the animals. This finding is of very high practical interest, as improvements in feed efficiency may result in significant reductions of waste outputs and production costs of fish farming. The putative beneficial effects that dietary OA may have on fish flesh quality in terms of lipid content are being analyzed as well as mechanisms involved in FI regulation at central peripheral levels. A new abstract containing data of neuropeptides expression and fatty acid-sensing mechanisms will be submitted soon.
Acknowledgments: Present study was funded by FEDER-Operational Programme Competitiveness and Internationalization and FCT under the project SPO3 (ref. POCI-01-0145-FEDER-030377) and by Programa Operacional Mar2020, Portugal 2020 under the project InovFeed (ref. MAR-02.01.01-FEAMP-0111)
Reference: Hammad, S., Pu, S., Jones, P.J., 2016. Current Evidence Supporting the Link Between Dietary Fatty Acids and Cardiovascular Disease. Lipids 51, 507–517. https://doi.org/10.1007/s11745-015-4113-x
Librán-Pérez, M., Otero-Rodiño, C., López-Patiño, M.A., Míguez, J.M., Soengas, J.L., 2014. Central administration of oleate or octanoate activates hypothalamic fatty acid sensing and inhibits food intake in rainbow trout. Physiol. Behav. 129, 272–279. https://doi.org/10.1016/j.physbeh.2014.02.061