Dietary supplementation with n-3 high unsaturated fatty acids decreases serum lipid levels and improves flesh quality in the marine teleost golden pompano Trachinotus ovatus

Abstract

The roles of dietary n-3 high unsaturated fatty acids (HUFA) in fish as essential fatty acids for normal growth and development have received much attention, especially those in marine carnivorous teleosts. However, their effects on flesh quality and physicochemical properties have seldom been reported. In this study, six isoproteic, isolipidic, and isocaloric diets (D1–D6) containing different levels of n-3 HUFA were prepared. D1 contained 2.30% n-3 HUFA using fish oil as the sole lipid source, while D2–D6 contained 0.64, 1.00, 1.24, 1.73, and 2.10% n-3 HUFA, respectively, using a blend of vegetable oils supplemented with docosahexaenoic acid-, eicosapentaenoic acid-, and arachidonic acid-enriched oils. After the golden pompano (Trachinotus ovatus) juveniles were fed the diets in sea nets for 8 weeks, their growth performance showed no significant difference among the six dietary groups (P > 0.05). However, serum levels of total triglyceride, total cholesterol, and low-density lipoprotein cholesterol were markedly decreased with increasing dietary n-3 HUFA levels in D2–D6 groups (P < 0.05). Moreover, flesh quality indices, including water holding capacity, gumminess, lipid content, and total antioxidant capacity, were largely improved in the D4 and D5 groups compared with the other groups. The levels of n-3 HUFA in the muscle increased substantially with increasing dietary n-3 HUFA level. Consistent with the increased lipid content, the expression levels of genes related to lipid anabolism, such as fatty acid synthetase (fas), acetyl-CoA carboxylase (acc), fatty acid translocase 36 (cd36), 1-acyl-glycerol-3-phosphate acyltransferase 3 (agpat3), and peroxisome proliferators-activated receptor gamma (pparγ), were significantly up-regulated in muscle of D4 group (P < 0.05). These results demonstrate that dietary n-3 HUFA supplementation at 1.24%–1.73% can decrease serum lipid concentration and improve flesh quality in juvenile golden pompano.