Effect of high plant protein diet supplemented with Lysophospholipids-butyrate on the growth performance, liver health and intestinal morphology of Largemouth bass (Micropterus salmoides)

This study was conducted to evaluate the effects of dietary supplementation with lysophospholipids-butyrate (LPB) in a high plant protein diet on the growth performance, liver health, and intestinal morphology of Largemouth bass (Micropterus salmoides). Three experimental diets were formulated: a positive control diet (PC) containing 15.00 % soybean meal (SBM) and 13 % chicken meal;a high-plant-protein diet (HPP) with 28.00 % SBM; a diet (LPB) supplemented LPB at 0.1 % in HPP. Largemouth bass with an average initial body weight of 9.3 g were fed for 60 days, with 4 replicates per group and 20 fish per replicate. The results demonstrated that the HPP group exhibited significantly lower final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) compared to the PC group. Moreover, the HPP diet induced a notable increase in liver collagen fiber and liver lipid content, which was alleviated by LPB supplementation. In comparison to the HPP group, the LPB group showed significant increases in serum albumin and albumin/globulin, along with a significant decrease in alanine aminotransferase activity (P < 0.05). Compared with the PC group, the mRNA levels of acetyl-CoA carboxylase-1 (ACC-1), diacylglycerol acyltransferase (DGAT), carnitine palmitoyl transferase-1 (CPT-1) and tumor necrosis factor-alpha (TNF-alpha) in HPP group were increased significantly (P < 0.05), while adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL) as well as apoptotic gene B-cell lymphoma-2 (Bcl-2) were significantly down-regulated. The mRNA levels of fatty acid synthase (FAS), ACC-1, peroxisome proliferator activated receptor-alpha (PPAR-alpha), ATGL, interleukin-1 beta (IL-1 beta), transforming growth factor-beta (TGF-beta) and Bcl-2 were up-regulated (P < 0.05), while DGAT and TNF-alpha were down-regulated in the LPB supplemented groups than that in the HPP group (P < 0.05). In conclusion, the supplementation of 0.1 % LPB can alleviate liver lipid accumulation and fibrosis caused by high level of soybean meal.