The effects of dietary supplementation of α-lipoic acid on the growth performance, antioxidant capacity, immune response, and disease resistance of northern snakehead, Channa argus

The study was the first time to explore the positive effects of alpha-LA on growth performance, antioxidant capability, immunity, and disease resistance of northern snakehead (Channa argus). Five hundred and forty northern snakehead fish (initial body weight: 8.74 +/- 0.12 g (mean +/- SE)) were randomly allocated into six groups with three replicates each. Six diets supplemented with alpha-LA at doses of 0 (CON), 300 (LA300), 600 (LA600), 900 (LA900), 1200 (LA1200), and 1500 (LA1500) mg/kg were fed to northern snakehead for 8 weeks. The results demonstrated that, when compared with the control group, optimal dietary alpha-LA increased the weight gain (WG), protein efficiency ratio (PER), and specific growth rate (SGR) and reduced the feed conversion ratio (FCR) of the fish (P < 0.05). Also, optimal dietary alpha-LA enhanced the immune-related parameters and antioxidant enzyme parameters levels in the head kidney, spleen, and liver of northern snakehead (P < 0.05). Dietary alpha-LA upregulated the mRNA expression levels of anti-inflammatory cytokines (il10 and tgf beta) and antioxidant related genes (gst, gsh-px, gr and Cu/Zn sod), down-regulated the pro-inflammatory cytokines (il1 beta, il8, il12 and tnf alpha) mRNA levels in the liver, spleen and head kidney of the northern snakehead (P < 0.05). The above results demonstrated that optimal dietary alpha-LA showed enhancement effects on the growth, antioxidant and anti-inflammatory capability, and immune response of northern snakehead. The survival rates in all alpha-LA treatments were significantly raised after the challenge with Aeromonas veronii (P < 0.05). Based on the quadratic regression analysis of WG, GSH-Px, LYS, and il1 beta, the optimal dietary alpha-LA levels were estimated to be 737.0, 775.0, 890.0, and 916.7 mg/kg, respectively. Considering the overall responses in growth performance, antioxidant status, immune response, and inflammatory factors, the recommended dose of alpha-LA in the diet of fish is 737.0-916.7 mg/kg.

Automated summary

This study is the first to investigate the positive effects of alpha-LA on the growth performance, antioxidant capability, immunity, and disease resistance of northern snakehead. The results showed that optimal dietary alpha-LA improved the weight gain, protein efficiency ratio, specific growth rate, and reduced the feed conversion ratio of the fish. Additionally, it enhanced the immune-related parameters and antioxidant enzyme levels, and regulated the expression of inflammatory and antioxidant genes. The recommended dose of alpha-LA in fish diet is 737.0-916.7 mg/kg.