DHA-enriched marine phosphatidylcholine alleviates fat deposition and mediates phospholipid remodeling in largemouth bass（Micropterus salmoides）

This study aimed to investigate the effects of DHA-rich phosphatidylcholine (DHA-PC) extracted from Atlantic herring (Clupea harengus) eggs on growth performance, fat metabolism, and lipid composition of largemouth bass (Micropterus salmoides). Three groups of equal nitrogen (48% crude protein) and equal fat (12% crude fat) feed were set up, supplemented with 0%, 3% and 6% DHA-PC respectively, and named CON group, MDHAPC group and HDHAPC group. The largemouth bass with initial weight of 4.31 ± 0. 038 g were studied for 8 weeks. The addition of DHA-PC had no significant effect on the growth performance of largemouth bass, but significantly reduced the dirt-to-body ratio (VSI); In terms of body composition, DHA-PC significantly reduced the crude fat content of fish; The analysis of fatty acid composition showed that DHA-PC had a significant effect on improving the contents of DHA and EPA in fish, serum and muscle. In terms of physiological and biochemical indexes related to lipid metabolism, DHA-PC significantly reduced the content of triglyceride (TG) in serum, liver and muscle; DHA-PC significantly reduced the mRNA expression levels of genes related to fat synthesis (acc1 and fas, etc.) in liver and muscle, but significantly increased the mRNA expression levels of genes related to lipolysis (lpl) and fatty acid oxidation (cpt1). Muscle tissue lipidomics analysis found that the addition of DHA-PC altered the distribution of fatty acids in PC, PE (phosphatidylethanolamine), and PI (phosphatidylinositol). Analyzing the expression of genes related to phospholipid synthesis, it was found that DHA-PC significantly promoted the mRNA expression levels of cct-α, cctβ and pemt. DHA-PC had no significant effect on the growth performance of largemouth bass, and significantly reduced fat levels within tissues by inhibiting fat synthesis and promoting fatty acid oxidation and lipolysis. DHA-PC extracted from aquatic by-products is a good lipid-lowering feed additive for largemouth bass while maximizing the utilization of marine resources.