An 8-week study was carried out to examine the influence of dietary Biotronic® Top3 (BTT3) which is a blend of short chain fatty acids (formate, propionate, and acetate), a phytogenic agent (cinnamaldehyde) and a permeabilizer complex (Biomin®) on growth and some physiological responses of whiteleg shrimp (Litopenaeus vannamei) juveniles (2.7 g). In this regard, five isoproteic (∼38%) diets were formulated that supplemented with BTT3 at 0.3, 0.6, 0.9 and 1.2 g/kg. A diet without BTT3 was used as a control. Shrimps were allocated into 15 circular fiberglass tanks filled with 300 L seawater (20 shrimp per tank) and each dietary treatment replicated in triplicate. Shrimps were handfed at 7 % of their initial biomass thrice. Growth rate and feed conversion ratio in shrimps fed with 0.3 g BTT3/kg diet were more than the control (P < 0.05), but higher dietary BTT3 levels did not improve growth and feed utilization compared to those fed 0.3 g BTT3/kg diet (P > 0.05). Protein deposition in the whole body of shrimps fed with 0.3 or 0.6 g BTT3/kg diets was increased compared with the control (P < 0.05). Total alkaline proteases in shrimp fed BTT3-supplemented diets was elevated compared to the control (P < 0.05). The activity of antioxidant enzymes including catalase, superoxide dismutase and glutathione peroxidase were increased in the hepatopancrease of shrimps fed BTT3-supplemented diets; meanwhile, the level of lipid peroxidation (i.e., malondialdehyde concentration) reduced by increasing dietary BTT3 level (P < 0.05). Shrimps fed diets supplemented with 1.2 g BTT3/kg and the control, had the highest and lowest plasma phenoloxidase activity, respectively. The plasma alkaline phosphatase content in shrimps fed BTT3-supplemented diets was higher than the control. The highest relative abundance of prophenoloxidase gene mRNA transcript was in the hepatopancreas of shrimps fed 1.2 g BTT3/kg diet. The relative abundance of lysozyme and penaeidin-3a genes mRNA transcript in the
