Assessing the impact of a diet incorporating folic acid and/or chitosan nanoparticles loaded with folic acid (FA/CNPs) on the growth performance and immune response of juvenile beluga sturgeon (Huso huso)

The study examined how chitosan nanoparticles loaded with folic acid (FA/CNPs) and/or folic acid impact on growth performance and immune response of juvenile beluga sturgeon (Huso huso). Fish weighing an average of 15.3±0.7 g were placed in 15 fiberglass tanks with 25 fish per tank and given diets with varying levels of FA/CNPs and/or folic acid: 0 (control), treatment 1 (T1: 1 mg of FA/CNPs per kg of feed), treatment 2 (T2: 1 mg of folic acid per kg of feed), treatment 3 (T3: 1 mg of FA/CNPs + 1 mg of folic acid per kg of feed), and treatment 4 (T4: 2 mg of FA/CNPs + 1 mg of folic acid per kg of feed) for 8 weeks. The findings demonstrated notable improvements in various growth indicators, including daily growth rate, body weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and immune indices (total serum protein, levels of immunoglobulin M, total immunoglobulin, and complement C3). Additionally, antioxidant parameters such as catalase, superoxide dismutase, and glutathione peroxidase also showed significant improvements with T3 and T4 treatments that incorporated both FA/CNPs and folic acid compared to the control group (P < 0.05). Furthermore, these treatments resulted in lower serum cholesterol and triglyceride levels compared to other treatments, particularly the control group (P < 0.05). The study found that incorporating FA/CNPs and folic acid into the diet resulted in notable improvements in red and white blood cell counts, lymphocytes and neutrophils percentages, hematocrit, and haemoglobin concentration, as well as reduced levels of triglycerides, cholesterol, ALT and AST enzymes, and cortisol in the blood. It is recommended to use a combination of 1–2 mg/kg of FA/CNPs with 1 mg/kg of folic acid to improve growth and general immune status of juvenile great sturgeon.