Effects of different levels of polyethylene glycol glycerol ricinate added to feed on growth performance and fat metabolism of young American eel Anguilla anguilla

The PEGR0.5, PEGR1, and PEGR2 groups showed a significant increase in the crude protein content of the whole fish (P<0.05), a significant decrease in the crude fat content of the liver (P<0.05), and a significant reduction in lipid droplets in the Oil Red O stained sections; There was no significant change in the above indicators in the PEGR4 group (P>0.05). Compared with the PEGR0 group, the PEGR added group showed a significant decrease in total cholesterol levels (P<0.05), while the PEGR0.5 and PEGR1 groups showed a significant decrease in triglyceride levels (P<0.05) and a significant increase in high-density lipoprotein cholesterol levels (P<0.05).

The PEGR0.5 group had the best lipid-lowering effect; The activities of hormone sensitive lipase and carnitine palmitoyltransferase 1 were significantly increased in the PEGR0.5 and PEGR1 groups (P<0.05), while the activity of fatty acid synthase was significantly decreased in the PEGR0.5 group (P<0.05). Non targeted metabolomics analysis showed that pathways such as glycerophospholipid metabolism, glycerolipid metabolism, linoleic acid metabolism, and alpha linolenic acid metabolism were upregulated in the liver of the PEGR0.5 group, which helped regulate blood lipid levels.

In conclusion, the addition of PEGR at an appropriate level in the feed can promote the growth of young American eel and regulate fat metabolism. It is suggested that the addition level of this emulsifier in the feed should be 0.50-0.51 g/kg.