Vitamin D3 is essential for calcium and phosphorus metabolism, antioxidant defense, and immune regulation in vertebrates, and recent evidence indicates similar roles in crustaceans. Pacific white shrimp ( Penaeus vannamei) is the most widely farmed aquaculture species, yet its dietary requirement for vitamin D₃ remains unclear. This study therefore evaluated the effects of graded dietary vitamin D3 levels on growth, antioxidant capacity, immunity, digestive enzymes, tissue histology, and disease resistance in P. vannamei.
Six experimental diets were formulated to contain 0, 37.5, 75, 150, 300 and 600 μg /kg vitamin D₃ supplementation (designated as CON, VD37.5 , VD75 , VD150 , VD300 and VD600). HPLC analysis confirmed actual dietary vitamin D3 levels of 4.8, 37.6, 78.4, 152.8, 313.7 and 609.4 μg /kg diet. A total of 600 shrimp (initial body weight: 2.02 ± 0.01 g) were randomly distributed into 24 tanks (240 L, 25 shrimp/tank) with four replicates per treatment and fed the diets at 3–6% of body weight per day for 10 weeks. After the feeding trial, a Vibrio harveyi challenge test was conducted by immersion at 8.1 × 10⁶ CFU/mL with 16 shrimp per tank in triplicate for 11 days.
Growth performance (final body weight, weight gain, specific growth rate) was significantly higher in VD75 , VD150 and VD300 compared to CON ( P < 0.05). Feed conversion rate was significantly lower in VD75 , while protein efficiency rate was significantly higher in VD75 than in CON ( P < 0.05). Survival and feed intake were not significantly different among groups ( P > 0.05). During Vibrio harveyi challenge, all vitamin D3-supplemented groups exhibited significantly higher survival than CON ( P < 0.05). In hemolymph, lysozyme activity was significantly higher in VD300 and VD600 compared to CON ( P < 0.05) and phenoloxidase activity was highest in VD75 compared to CON ( P < 0.05). Hemolymph calcium level and alkaline phosphatase activity were significantly higher in VD150 , VD300 and VD600 compared to CON ( P < 0.05), while hemolymph inorganic phosphorus level was significantly higher in CON than in VD37.5 and VD75 ( P < 0.05). In carapace, calcium content was significantly higher in VD300 and VD600 ( P < 0.05), phosphorus content was significantly higher in VD37.5 ( P < 0.05). In hepatopancreas, s uperoxide dismutase activity was significantly higher in VD37.5 , VD75 and VD150 ( P < 0.05), glutathione peroxidase in VD37.5 and VD75 ( P < 0.05), catalase in VD37.5 , VD75 and VD300 ( P < 0.05). M alondialdehyde levels were significantly lower in VD37.5 , VD75 and VD150 compared to CON ( P < 0.05). T rypsin activity was significantly increased in VD37.5 , VD75 and VD150 ( P < 0.05), and lipase activity was higher in VD150 compared to CON ( P < 0.05).
In conclusion, dietary supplementation of vitamin D3 improved growth, feed efficiency, non-specific immunity, digestive and antioxidant enzyme activities , mineral deposition and V. harvei resistance in P . vannamei. The q uadratic-plateau regression model estimated the optimal dietary vitamin D3 level for weight gain at 53.6 μg/kg.