Dietary acetate promotes growth and nutrients deposition in Nile tilapia (Oreochromis niloticus) through increasing acetyl-CoA-triggered energy production

Short-chain fatty acids (SCFAs) such as acetate render multiple beneficial biological effects in living organisms. However, the systematic effects of acetate in fish energy metabolism are still lacking. This study explored the effects of dietary sodium acetate on energy metabolism by determining growth performance, acetate and macro nutrients metabolism, and liver health in Nile tilapia (Oreochromis niloticus). Thirty fingerlings (5.0 ± 0.30 g) were fed with a control (CN) or control containing 1800 mg/kg sodium acetate diet (NAAC) in triplicate for eight weeks. The results showed that NAAC increased significantly weight gain, carcass ratio, condition factor, and feed efficiency of Nile tilapia. Correspondingly, the NAAC significantly enhanced insulin sensitivity, activated the mechanistic target of rapamycin complex 1 (mTORC1) pathway, and increased glycogen, lipid and protein content in fish. Contrastingly, the fish fed with NAAC had lower of serum glucose and liver essential amino acid levels and liver fatty acid catabolism level than those fed with CN. However, the NAAC increased significantly the levels of acetyl-CoA, acetylcarnitine, β-hydroxybutyric acid and overall proteins acetylation. Moreover, the fish fed with NAAC had higher levels of NADH/NAD+, ATP, and expression of key genes related to NADH, and ATP production than those fed with CN. Additionally, the NAAC treatment upregulated significantly the antioxidant-related genes expression and downregulated the apoptotic genes expression, accompanied by reduced serum AST activity and apoptosis level. Taken together, dietary sodium acetate inhibited catabolism of protein, lipid and carbohydrate but increased dietary sodium acetate-sourced acetyl-CoA catabolic energy supply and activated the mTORC1 pathway, and finally increased macro nutrients deposition and promoted growth in fish. This study suggests that SCFAs such as acetate could be used as potential feed additives to promote feed utilization and exert protein-sparing effects.