Sodium butyrate ameliorates high-fat diet-induced growth retardation and gut injury in largemouth bass (Micropterus salmoides) by modulating gut mucosal barrier and microbiota

The investigation was to validate the alleviating effect of sodium butyrate on high-fat diet-induced gut injury and growth inhibition in largemouth bass ( Micropterus salmoides ). Five diets were designed: four high-fat diets (18 % crude lipid) supplemented with sodium butyrate at 0 % (HF), 0.05 % (HFS1), 0.1 % (HFS2), and 0.2 % (HFS3), as well as a control diet (C, 10 % crude lipid). Three tanks (30 fish each tank) were randomly allocated to each diet. Fish (4.0 g) were fed to apparent satiation for sixty days. Results indicated that HF dramatically reduced fish growth and induced oxidative stress, mucosal barrier dysfunction, gut inflammation, and gut dysbiosis compared to C. However, in comparison to HF, HFS1, HFS2, and HFS3 diets significantly promoted feed intake and weight gain rate, relieved oxidative stress by increasing antioxidant defense (e.g., total superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and nuclear factor E2-related factor 2) and reducing malondialdehyde content, enhanced mucosal barrier by upregulating the expression of occludin, mucin3a, zona occluding-1, hypoxia-inducible factor-1α, and lysozyme, and reduced inflammation by downregulating the expression levels of interleukin 1β and tumor necrosis factor α ( P  < 0.05). Moreover, HFS1 and HFS3 dramatically reduced Tenericutes and Mesomycoplasma abundance, whereas HFS1 increased Lactococcus abundance when compared to HF ( P  < 0.05). Correlation analysis revealed a significant relationship between fish growth and gut injury with mucosal barrier proteins and gut microbiota (e.g., Tenericutes, Mesomycoplasam , and Lactococcus ) ( P  < 0.05). These findings suggested that sodium butyrate can help mitigate the detrimental effects of high-fat diets on fish growth and gut health.