The effects of diet supplementation with inorganic and nanoparticulate iron and copper on growth performance, blood biochemical parameters, antioxidant response and immune function of snow trout Schizothorax zarudnyi (Nikolskii, 1897)

Iron and copper are two essential micronutrients that play important roles in vital biological processes, key enzymes and the immune system. In this study, the effects of diet supplementation with inorganic and nanoparticulate iron and copper on growth performance and hemato-immunological responses of snow trout Schizothorax zarudnyi (23.97 ? 0.45 g) were investigated for 84 days. The fish were fed by seven experimental diets supplemented with 0 mg copper and iron (Cu, Fe) (control), 150 mg inorganic iron (FeI), 3 mg inorganic copper (CuI), 150 mg FeI and 3 mg CuI (FeI + CuI), 150 mg nanoparticulate iron (FeNPs), 3 mg nanoparticulate copper (CuNPs), 150 mg FeNPs and 3 mg CuNPs (FeNPs+CuNPs) per kg of diet. The results showed that the diet supplementation with Fe and Cu improved the growth and feeding indices compared with the control treatment; however, the nanoparticulate Fe and Cu acted more effectively than their inorganic counterparts. The values pertaining to the most hematological parameters, such as RBCs, hematocrit and hemoglobin, were higher in nanoparticulate treatments than in the inorganic ones (P < 0.05). Serum total protein, albumin, globulin, cholesterol and triglyceride increased while glucose decreased with Fe and Cu supplementation to the diets, especially with the nanoparticulate form. The dietary addition of Fe and Cu, especially in nanoparticulate form, improved the levels of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), whereas it decreased the serum malondialdehyde (MDA) compared with the control treatment (P < 0.05). The activities of liver enzymes showed a decreasing trend in the fish fed with inorganic and nanoparticulate Fe and Cu compared with the control treatment. Lysozyme, complement component (C3) and alternative complement activity (ACH50) were improved in the fish fed with the diets supplemented by Fe and Cu, especially in the form of nanoparticulate, consequently increasing the bactericidal activity of blood serum. In total, the concurrent adding of dietary nanoparticulate Fe and Cu improved the fish growth, antioxidant and hemato-immunological indices more effectively than their individual supplementation as well as the inorganic and control treatments. These promising findings are valuable as a basic knowledge in formulating performancebased diets for this endemic aquaculture candidate.

Automated summary

The supplementation of nanoparticulate forms of iron and copper in the diet was found to be more effective in improving the growth and hemato-immunological responses of snow trout compared to their inorganic forms.