Sodium butyrate mitigates aflatoxin B1 toxicity in largemouth bass

The aim of this study was to investigate the effects of aflatoxin B1 (AFB1) on growth performance, lipid metabolism, oxidative stress, histopathology, and gut microbiota composition in largemouth bass, and to evaluate the mitigation effect of sodium butyrate (SB). The initial body weight of largemouth bass was 3.38 ± 0.10 g, and the experimental period was 56 days. The experiments were divided into three groups: CON (basal diet without AFB1), AFB1 (basal diet +1.0 mg/kg AFB1), and SB (basal diet +1.0 mg/kg AFB1 +2.0 g/kg SB). The results showed that AFB1 significantly reduced the rate of weight gain in largemouth bass compared with CON, whereas there was no significant difference in the SB supplemented group. AFB1 decreased serum TG levels and increased CHO, HDL, and LDL levels, whereas SB addition did not mitigate these effects. In addition, blood glucose levels were also significantly lower in the AFB1 and SB groups compared to CON. In terms of oxidative stress, AFB1 exposure increased the activities of liver antioxidant enzymes, including GSH-Px, ACP, and AKP, while SB supplementation increased the activity of intestinal catalase CAT, both of which significantly increased the content of MDA. Histopathological results showed that AFB1 increased inflammatory responses in the gut and liver, which were attenuated by SB addition. In terms of gut microbial composition, AFB1 decreased the relative abundance of gut microbes in largemouth bass, whereas SB addition decreased the relative abundance of Firmicutes and Mycoplasma genera and increased the relative abundance of Proteobacteria. In conclusion, SB alleviated the negative effects of AFB1 on largemouth bass to some extent, especially in promoting growth performance, gut microbiota, and reducing inflammatory responses, providing a scientific basis for mitigating the adverse effects of AFB1 in the aquaculture industry.