Effect of dietary supplementation with Chlorella sorokiniana meal on the growth performance, antioxidant status, and immune response of rainbow trout (Oncorhynchus mykiss)

The aim of the study is to investigate whether dietary Chlorella sorokiniana supplementation could improve growth performance, antioxidant status, and immune response of Oncorhynchus mykiss. Three isonitrogenous (47%) and isolipidic (16.5%) diets supplemented with 0% (Control), 5% (5% CS), and 10% C. sorokiniana meal (10% CS) were assigned to O. mykiss (three replicates per diet, 30 fish in each replicate, initial body weight 165.24 ± 0.46 g). The results indicated that O. mykiss fed with 5% CS diet had an increased feeding rate (FR), specific growth rate (SGR), and weight gain rate (WGR) compared to the control (P < 0.05). Dietary 5% or 10% C. sorokiniana supplementation significantly increased activity levels of superoxide dismutase (SOD) in the liver and catalase (CAT) in the liver and head kidney. In addition, dietary supplementation with 10% C. sorokiniana also significantly increased activity level of glutathione peroxidase (GPX) and simultaneously decreased contents of malondialdehyde (MDA) in the liver and head kidney. Furthermore, fish fed with 5% CS or 10 CS diet demonstrated increased activity level of lysozyme (LYZ), higher content of immunoglobulin M (IgM), and upregulated transcriptional expression of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), hepcidin (HEP), and nuclear factor kappa-B (NF-κB) in the head kidney. Based on fish growth performance, antioxidant capacity, and immune response, dietary supplementation of 5% C. sorokiniana was recommended.