Abstract
This study investigated the effects of sodium propionate (SP) on intestinal microbiota and liver lipid metabolism in yellow catfish (Pelteobagrus fulvidraco). A control diet containing 42% crude protein was formulated, and experimental diets were created by supplementing 0.00%, 0.25%, 0.50%, 1.00%, and 2.00% SP. A total of 600 juvenile yellow catfish (averaging 3.20 ± 0.10 g) were randomly allocated into five dietary treatment groups (SP0 to SP4), with each group consisting of three replicate tanks (n = 3) and 40 fish per tank. The fish were fed their respective diets for 42 d. Results demonstrated that supplementation with 1.0% SP significantly improved weight gain rate (P < 0.001) and specific growth rate (P < 0.001), while reducing the feed conversion ratio (P = 0.002). Furthermore, 1.0% SP significantly enhanced intestinal pepsin (P < 0.001), amylase (P < 0.001), and lipase activity (P < 0.001), and significantly enhanced serum total antioxidant capacity (P = 0.006), superoxide dismutase (P < 0.001), and catalase activity (P = 0.044). 16S rRNA sequencing and quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that 1.0% SP supplementation significantly increased the relative abundance and copies of the beneficial bacteria Cetobacterium (P < 0.001). Liver lipid metabolism analysis showed that 1.0% SP significantly decreased liver total triglycerides (P = 0.027) and total cholesterol levels (P = 0.004). Moreover, 1.0% SP significantly upregulated the expression of genes associated with liver fatty acid oxidation, including peroxisome proliferator-activated receptor alpha (pparα) (P < 0.001), carnitine palmitoyltransferase (cpt) (P < 0.001), adipose triglyceride lipase (atgl) (P < 0.001), acyl-coenzyme a oxidase (aco) (P = 0.028), and hormone-sensitive lipase (hsl) (P < 0.001), while downregulating the expression of genes involved in fatty acid synthesis, such as fatty acid synthase (fas) (P < 0.001) and acetyl-coa carboxylase (acc) (P < 0.001). Histological analysis via hematoxylin-eosin staining revealed that SP supplementation significantly reduced liver steatosis and hepatocyte vacuolation. In conclusion, SP supplementation promotes fatty acid oxidation via the PPARα/ACO pathway, thereby reducing liver lipid accumulation. Additionally, SP supplementation significantly increased the survival rate of yellow catfish under acute ammonia stress (P < 0.001). These findings suggest that SP has potential as an environmentally-friendly dietary supplement to improve growth performance and physiological health, enhance liver lipid metabolism, and modulate the intestinal microbiota in yellow catfish.