Work

The effects of cholesterol supplementation in full-plant protein diets derived from different lipid sources on liver and intestinal health, bile acid metabolism in largemouth bass (Micropterus salmoides)

Year: 2026

Type: article

Abstract: Cholesterol plays an important role in the physiological metabolism of farmed animals. However, the cholesterol content in plant protein feeds does not meet the requirements of farmed animals. This study aimed to investigate the effects of dietary cholesterol supplementation on liver and intestinal health, bile acid metabolism in largemouth bass (Micropterus salmoides) fed full-plant protein diets using fish oil (FO) or soybean oil (SO) as lipid sources. Five diets were formulated: a fishmeal-based control diet (FFM), two full-plant protein diets with FO and SO as lipid sources (PFO, PSO), and two additional full-plant protein diets supplemented with 5g/kg exogenous cholesterol using FO or SO as lipid sources (PFC, PSC). A 50-day feeding trial was conducted. The results showed that fish fed full-plant protein diets exhibited liver inflammation, with hepatocyte vacuolation observed in PSO. Cholesterol supplementation alleviated liver damage induced by full-plant protein diets via up-regulating anti-inflammatory marker tgfβ and down-regulating pro-inflammatory markers (tnfα, il1β, nrf2, keap1) and oxidative stress-related genes (bach1, prx2, sod, cat). Intestinal health was compromised in fish fed full-plant protein diets, as evidenced by shortened intestinal mucosal length and width. Cholesterol supplementation improved intestinal health by up-regulating tight junction protein genes (claudin5, claudin11, occludin) and anti-inflammatory marker tgfβ, while down-regulating pro-inflammatory markers (tnfα, il1β, nrf2, keap1). Additionally, cholesterol supplementation significantly increased the bile acid content (TCA, TDCA, GCA) in the gallbladder of fish fed FO-based diets, but not in those fed SO-based diets. Further analysis revealed that cholesterol up-regulated the expression of bile acid synthesis genes (cyp8β1, hmgcr), bile acid transport genes (mrp2, mdr3, bsep), and bile acid reabsorption-related genes (ostα, ostβ, abst), thereby maintaining bile acid homeostasis. These findings provide insights into the application of cholesterol and full-plant protein diets in aquaculture and their implications for fish health.

Source: Aquaculture Reports

DOI: 10.1016/j.aqrep.2025.103340