Impact of dietary vitamin c on plasma metabolites, antioxidant capacity and innate immunocompetence in juvenile largemouth bass, Micropterus salmoides

The present study aimed to investigate the effects of dietary vitamin c on plasma metabolites, antioxidant ca- pacity and innate immunocompetence in juvenile largemouth bass. To achieve this, the fish were fed diets supplemented with 0 (basal), 25, 50, 75, 100, 125, 150, and 175 mg/kg dietary VC for 60 day. Then, fish were sampled and tissues were collected to determine antioxidant capacity and innate immunity. Also, post bacteria challenge evaluations were carried out. In the present study, hemorrhagic lip, hemorrhagic fin, dark skin col- oration, eroded fin and scoliosis were observed in AMP0 group. Dietary VC (AMP125, AMP150 and AMP175) significantly elevated plasma high density lipoprotein cholesterol, total protein and endogenous antioxidant enzyme activity and their hepatic mRNA level (superoxide dismutase, glutathione peroxidase and catalase), these treatments also lowered low density lipoprotein -cholesterol, aspartate aminotransferase, alanine amino- transferase concentration and Malondialdehyde. In addition, AMP125 and AMP150 significantly enhanced immune parameters (C3, C4 and IgM). Conclusively, dietary VC triggers antioxidant system, prevent oxidative stress and enhances some innate immune components. Moreover, dietary VC improves liver integrity and percentage survival rate during Aeromonas hydrophila infection. Dietary VC administration at 125 -150 mg/kg is suitable to enhance antioxidant and immune capacity in largemouth bass without negative effects on the growth and feed utilization efficiency.