The effects of nano-curcumin on growth performance, feed utilization, blood biochemistry, disease resistance, and gene expression in European seabass ( Dicentrarchus labrax ) fingerlings

Phytochemicals are used in fish farming to reduce stress and combat diseases during intensification. Recently, nanotechnology has represented a paradigm shift in the aquatic feed industry to improve the solubility, availability, and efficacy of phytochemicals. The purpose of this research was to investigate the effects of dietary supplementation with nano-curcumin (CUNE) on the growth, feed utilization, body composition, blood biochemistry, antioxidant status, disease resistance to Vibrio parahaemolyticus (V. parahaemolyticus), and the expression of insulin-like growth factor 1 (IGF-1), growth hormone (GH), interleukin-10 (IL-10), and interlukin-1 beta (IL-1 beta) genes in European Seabass (Dicentrarchus labrax) fingerlings. Fish (6.02 +/- 0.01) were randomly divided into four equal groups and fed varying levels of CUNE: 0 (CUNE0), 50 (CUNE1), 60 (CUNE2), and 70 mg/kg (CUNE3) of nano-curcumin for 56 days, respectively. The inclusion of dietary CUNE significantly improved the growth indices (final body weight and weight gain, and specific growth rate) and feed utilization (improved feed intake and lower FCR) of European seabass fingerlings (p<0.05). However, CUNE inclusion had no significant effect on body composition including the percentages of dry mater, crude protein, crude lipid, and ash (p>0.05). All CUNE groups established an enhancement in blood hematology in a dose-dependent manner, with CUNE3 demonstrating the highest values. CUNE supplementation (70 mg/kg diet) produced the highest levels of total protein, albumin, globulin, and triglycerides, as well as the lowest levels of glucose, and hepatic enzymes (ALT, AST, and ALP; p<0.05) compared to other groups. Furthermore, the CUNE-supplemented groups showed significant improvements in superoxide dismutase, catalase, and glutathione peroxidase, while reducing malondialdehyde (p<0.05). Additionally, the consumption of CUNE increased the expression of IGF-1, GH, and IL-10 genes in a dose-dependent manner (p<0.05). Interestingly, fish fed 70 mg of CUNE in their diets had lower expression of the IL-1 beta gene compared to the other groups (p<0.05). When the fish were challenged with V. parahaemolyticus, the addition of CUNE in their diets resulted in reduced mortality rates. Therefore, nano-curcumin could be considered as a natural feed additive to promote growth, feed utilization, and bacteria resistance via supporting antioxidant status, serum metabolites, and the regulation of GH, IL-10, and IGF-1 in the hepatic tissues of European seabass fingerlings.