Does the bioactive resveratrol modulate the fatty acid composition of gilthead sea bream (Sparus aurata)?

Abstract

Possibilities to improve the lipid quality of fish in favor of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) are increasingly important in times of fish oil supply restriction. A promising approach is the use of bioactive phytochemicals with LCPUFA increasing potential in diets of cultured fish. The objective of this study was to evaluate the bioactive resveratrol (RV) and its effects on the marine species gilthead sea bream. A three-factorial approach was chosen to investigate whether effects of RV also depend on dietary fish oil level and temperature of the rearing water. Juvenile gilthead sea bream were fed four different experimental diets over the duration of two months. The diets were formulated to contain two different fish oil levels, 6% DM (F6) and 2% DM (F2). These diets were either supplemented with 0.15% DM resveratrol (+RV) or remained un-supplemented, resulting in four diets (F6, F2, F6+RV, F2+RV). The experiment was carried out in a triplicate approach per dietary treatment, simultaneously at 19 °C and 23 °C rearing temperature. Dietary RV supplementation exhibited none or only minor effects on fish growth, performance and body composition, whereas effects of the rearing temperature and dietary fish oil level were present. Similarly, the fatty acid composition of gilthead sea bream whole body and fillet was rather affected by the rearing temperature and the dietary fish oil level than RV supplementation. In contrast, the liver fatty acid composition was modified by RV supplementation depending on the dietary fish oil level, but only at 19 °C rearing temperature. Most interestingly, the contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were increased when fish were fed diet F6+RV in comparison to diet F6, whereas EPA and DHA were decreased in livers of fish fed diet F2+RV in comparison to diet F2. Overall, dietary RV neither had beneficial, nor detrimental effects on fish growth, performance, and fatty acid composition of gilthead sea bream. The modification of EPA and DHA levels in livers of fish held at the low water temperature might indicate possible RV mediated mechanisms affecting fatty acids, which remain to be elucidated.