Effects of dietary phytosterol on growth, lipid homeostasis and lipidomics of largemouth bass (Micropterus salmoides)

Little information is available on how exogenous phytosterol (PS) affect the growth performance and lipid homeostasis in fish. In the present study, an 8-week feeding trial were used to investigate the effects of PS on growth performance, serum biochemical indexes, cholesterol (CHO) metabolism and lipidomics of juvenile largemouth bass (Micropterus salmoides). The treatment diets (PS1-PS5) were formulated with supplementation of 0.01 %, 0.02 %, 0.03 %, 0.04 %, and 0.05 % PS on basis of the control diet (C, crude protein 48.39 %, crude lipid 11.65 %). Results showed that the final body weight and specific growth rate of largemouth bass increased as the levels of PS addition increased, reaching stability in the PS3 group. The concentration of high-density lipoprotein cholesterol was elevated and low-density lipoprotein cholesterol was reduced in serum were elevated following PS intervention at 0.03 %. PS treatment reduced the expression of genes associated with endogenous CHO anabolism, while increasing CHO catabolism and suppressing the corresponding negative transcriptional regulators. Lipidomics results showed that the composition patterns of lipid classes between the C and PS4 groups were similar. 7 of triglyceride (TG), 5 of phosphatidylcholine (PC), 2 of PE (phosphatidylethanolamine) and 1 of DG (diglyceride) lipid moleculars were identified as the potential lipid biomarkers in PS4 group. Furthermore, PS4 treatment enriched the pathway of 'membrane component' and 'polyunsaturated fatty acid'. In conclusion, lipid and cholesterol metabolism were altered by the PS treatment, and the appropriate PS addition level was found to be 0.03 % based on the growth performance of the largemouth bass.