Effects of dietary alpha-lipoic acid on growth performance and hepatic lipid metabolism of largemouth bass (Micropterus salmoides) fed diet with high lipid supplementation

The experiment aims to investigate the effect of adding alpha-lipoic acid (α-LA) to high-fat diets on the growth performance and liver lipid metabolism of largemouth bass (Micropterus salmoides). Three isonitrogenous experimental diets were prepared: a basal diet with 14% crude lipid (D1), the second diet with 14% crude lipid added to α-LA (D2) and the third diet with 16% crude lipid added to α-LA (D3). M. salmoides (5.01±0.02) g initial weight juveniles ingested the three diets for 8 weeks. The results showed that the weight gain rate and specific growth rate of M. salmoides in groups D3 and D1 were not significantly different (P>0.05), but significantly higher than in group D2 (P<0.05); the protein efficiency and protein deposition rate of M. salmoides in group D3 were significantly higher than those in groups D1 and D2 (P<0.05). Serum triglycerides levels, glutamic oxaloacetic transaminase, and glutamic alanine transaminase activity were significantly lower in groups D2 and D3 compared to group D1 (P<0.05), while the difference in total cholesterol levels was not significant between the groups (P>0.05). Liver vacuolation and fat deposition were significantly lower in groups D2 and D3 than in group D1 (P<0.05). The hepatic metabolome results showed that the biosynthetic metabolic pathway of unsaturated fatty acids was significantly upregulated in group D3 compared to group D1 (P<0.05). Muscle fatty acids were significantly elevated in group D3 for pentadecanoic acid, heptadecanoic acid, and 21 carbonic acids (P<0.05). The contents of arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) in muscle were significantly higher in groups D2 and D3 (P<0.05). High-lipid diet with α-LA enhanced lipolysis, inhibited lipid synthesis through the biosynthetic metabolic pathway of unsaturated fatty acids, and reduced hepatic lipid accumulation, as well as increased ARA, DHA, and EPA deposition in muscle.