Dietary bamboo vinegar powder improves growth performance, immunity, antioxidant capacity and lipid metabolism of largemouth bass (Micropterus salmoides)

Abstract

Bamboo vinegar powder (BVP), a secondary product of bamboo charcoal production, contains multiple bioactive compounds. However, its effects on largemouth bass remain unclear. To investigate these effects, six experimental diets containing different BVP levels (0, 0.5, 1.0, 2.0, 4.0, and 8.0 g/kg) were designed, and a 56-day feeding experiment was conducted on largemouth bass (Micropterus salmoides, 7.00 ± 0.02 g). Results demonstrated significant increase in the weight gain rate (P < 0.05) and specific growth rate (P < 0.05) and decrease in the feed conversion ratio (P < 0.05) with administration of diet containing 2.0 g/kg BVP. In addition, BVP (0.5–8.0 g/kg) significantly improved the levels of health indicators, such as aspartate aminotransferase, alanine transaminase, and alkaline phosphatase (P < 0.05) in the liver. In terms of antioxidative properties, BVP (1.0–2.0 g/kg) improved the levels of antioxidant enzymes, including total antioxidant capacity (P < 0.05) and catalase (P < 0.05), reduced the malondialdehyde content (P < 0.05), and upregulated the expression of nuclear factor erythroid 2-related factor 2 (P < 0.05). Regarding lipid metabolism, BVP (1.0–8.0 g/kg) decreased the triglyceride (P < 0.05) and total cholesterol (P < 0.05) levels in the liver and improved hepatic lipid metabolism by upregulating the expression of lipid transport (hormone-sensitive lipase and lipoprotein lipase) and lipid metabolism (fatty acid transport protein and microsomal triglyceride transfer protein) genes (P < 0.05). With regard to inflammation, BVP (0.5–4 g/kg) modulated the expression of inflammatory factors (interleukin-8, transforming growth factor-β, and interleukin-10; P < 0.05) to improve the inflammatory response. Collectively, these results suggested that dietary BVP at a level of 2.0 g/kg can help improve growth performance, antioxidant capacity, and inflammatory response and reduce lipid deposition in the liver of largemouth bass.