| Summary: | This study was conducted to investigate the impacts of potassium diformate (KDF) on growth performance, fillet quality, plasma indices, immune response and intestinal morphology of juvenile Trachinotus ovatus. Six diets with 0 (KDF1), 3.00 (KDF2), 6.00 (KDF3), 9.00 (KDF4), 12.00 (KDF5) and 15.00 (KDF6) g/kg KDF were formulated to feed T. ovatus (average fish weight: 5.87 ± 0.03 g) for 8 weeks. The results indicated that 3.00 g/kg and 6.00 g/kg KDF significantly increased the growth parameters of juvenile T. ovatus (P < 0.05), whereas 6.00 g/kg and 9.00 g/kg KDF significantly reduced feed conversion ratio (P < 0.05). KDF level presented a significant improvement on fillet quality of juvenile T. ovatus (P < 0.05). With the increasing levels of KDF, triglyceride and glucose of plasma significantly declined (P < 0.05), whereas high density lipoprotein cholesterol significantly increased (P < 0.05). 6.00 g/kg dietary KDF significantly up-regulated mRNA levels of Nrf2, CAT, CuZn-SOD, MnSOD (P < 0.05) and increased antioxidative enzyme activities in liver (P < 0.05). Furthermore, 6.00 g/kg KDF supplementation significantly enhanced immune function of juvenile golden pompano by regulating the expression levels of hepatic NF-κB, TGF-β, ZO-1, Occludin and Claudin-3a (P < 0.05). 6.00 g/kg KDF significantly improved intestinal morphology compared with KDF1 diets (the control) (P < 0.05). In conclusion, the supplement of dietary KDF was beneficial for T. ovatus by promoting growth performance, improving fillet quality and intestinal morphology and enhancing immune response. The optimum supplement level of KDF in T. ovatus diet was 6.58 g/kg based on WGR.
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