Sodium butyrate improves the growth performance, intestinal immunity, and ammonia tolerance of yellow catfish Pelteobagrus fulvidraco by increasing the relative abundance of Candidatus_Arthromitus

The study aimed to analyze the effect of dietary sodium butyrate (SB) on intestinal digestive enzyme activity, liver physiological status, immune parameter, intestinal microbiota structure and composition, and ammonia tolerance in yellow catfish. Over the course of an 8-week experiment, four separate groups including 480 healthy male yellow catfish (1.52 +/- 0.66 g) were fed diets containing varying concentrations of SB: 0, 0.05, 0.1, and 0.2%. Following this, an acute ammonia stress experiment that lasted for 96-h was conducted. The study showed that dietary supplementation of SB can improve growth performance and feed utilization (weight gain rate increased from 163.66 to 226.1%; specific growth rate increased from 1.73 to 2.11%/d; feed conversion rate decreased from 2.02 to 1.34), and increase intestinal digestive enzyme activity (lipase increased from 22.66 to 41.46 U/mg prot; amylase increased from 0.38 to 0.46 U/mg prot; pepsin increased from 10.13 to 12.83 U/mg prot). Plasma total protein (from 510.79 to 523.02 mu g/mL), 50% hemolytic complement (from 35.46 to 40.46 U/ mL), and immunoglobulin M (from 0.45 to 0.48 g/L) increased as dietary SB levels. On the contrary, plasma glucose (from 6.2 to 3.39 mmol/mL), high-density lipoprotein cholesterol (from 0.38 to 0.25 mmol/mL), aspartate aminotransferase (from 55.66 to 37.36 U/L), alanine aminotransferase (from 358.82 to 283.25 U/L), superoxide dismutase (from 163.84 to 147.13 U/mL), catalase (from 152.89 to 135.07 U/mL), tumor necrosis factor-alpha (from 67.58 to 62.13 pg/mL), interleukin-1 (from 40.07 to 30.96 pg/mL), and interleukin-8 (from 57.16 to 52.16 pg/mL) decreased with dietary SB levels. In addition, dietary supplementation of 0.2% SB significantly increased the relative abundance of Candidatus_Arthromitus in intestine by approximately 22-fold. To sum up, the utilization of SB has potential to enhance fish growth performance, elevate its physiological status, and improve its ability to tolerate acute ammonia toxicity. This is achievable by increasing the prevalence of Candidatus_Arthromitus in the intestine.