Background High-fat diets (HFD) are widely used in aquaculture due to their low cost, low nitrogen emission and “protein-saving effect”. However, long-term feeding of HFD can easily lead to liver lipid accumulation, lipid metabolism disorders, oxidative stress, inflammation, and apoptosis in fish, thus restricting the development of the industry. Short-chain fatty acids (SCFAs) such as acetic acid have antioxidant, anti-inflammatory, and lipid metabolism modulating potential. Sodium acetate, as its stabilized form, has been less studied in fish feeds, and there is a lack of systematic research especially in mitigating HFD-induced liver injury in carnivorous fish such as largemouth bass.
Objective The aim of this experiment was to investigate the effect of sodium acetate on growth performance and liver health of largemouth bass reared on high-fat diets.
Method In this experiment, 270 largemouth bass with an initial weight of (2.7±0.15) g were selected for the study. The fish were randomly divided into three groups: a control group (CON group, 10% crude fat), a high fat diet group (HFD group, 18% crude fat), and a high fat diet group with 0.2% sodium acetate added (HFD+SA group, 18% crude fat). Each group had three replicates, with each replicate containing 30 fish. The trial lasted for 8 weeks.
Result The results of the study demonstrated that adding 0.2% of sodium acetate to a high-fat diets significantly boosted the growth performance of largemouth bass (increased weight gain, feed intake, specific growth rate and condition factor, reduced feed coefficients). Improved liver antioxidant capacity (increased total antioxidant capacity, catalase and superoxide dismutase activities, reduced malondialdehyde levels). Ameliorated liver lipid metabolism disorders (lowered lipid droplet area, triglyceride, total cholesterol, and LDL cholesterol levels, increased HDL cholesterol levels, up-regulated the relative expression of the lipolytic genes cpt-1, acox, and pparα, and down-regulated the relative expression of the lipid synthesis genes fas, accα, dgat, and srebp1c). Ameliorated the pathological damage of liver tissue with vacuolization, nucleolysis and disappearance of cell nuclei. Reduced liver inflammation (down-regulated the relative expression of pro-inflammatory genes tnf-α, il-8, and nf-κb) and apoptosis (down-regulated the relative expression of pro-apoptotic genes p53, bax, cyt-c, caspase3, and caspase9).
Conclusion The study showed that the addition of sodium acetate to high-fat feeds could improve the growth performance of largemouth bass, alleviate the disorder of liver lipid metabolism, improve the antioxidant capacity, and reduce the liver damage. The results of the study can provide scientific basis for the healthy breeding of largemouth bass.
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