The present study aimed to compare the nutritional effects of cholesterol, bile acids, and combination of cholesterol with bile acids in plant-based diets on juvenile genetically improved farmed tilapia (GIFT, ). The isonitrogenous (32 g/kg crude protein) and isolipidic (76 g/kg crude fat) diets (Con diet) were based on plant protein sources, which included corn gluten meal, soybean meal, cottonseed meal and rapeseed meal. The Con diet was supplemented with 12 g/kg cholesterol (CHO diet), 0.2 g/kg bile acids (BAs diet), a combination of 12 g/kg cholesterol and 0.2 g/kg bile acids (CHO-BAs diet), respectively. Each diet was fed to three tanks in an indoor recirculating aquaculture system for 9 weeks. Results showed that compared to the Con group, fish had a higher weight gain rate, hepatosomatic index, and a lower feed conversion ratio in the CHO-BAs group. The highest levels of whole-fish fat and ash were found in the Con group. Serum parameters (including activities of alanine aminotransferase and aspartate transaminase, along with levels of glucose and triglyceride except for total cholesterol) were significantly lower in the CHO, BAs, and CHO-BAs groups than those in the Con group. Histological examination revealed that fish in the Con group exhibited severe hepatocyte vacuolization and diminished hepatocyte proliferation. Gene expression analysis indicated that the transcriptional levels of bile acid metabolism-related genes (including , , ) were significantly up-regulated in the CHO-BAs group, whereas cholesterol metabolism-related genes ( and ) were significantly down-regulated in both CHO and CHO-BAs groups. Moreover, UPLC-MS/MS analysis revealed that the higher taurine-conjugated bile acids (T-BAs), followed by free bile acids (Free-BAs) and glycine (G-BAs) were determined in tilapia bile. Among these, taurochenodeoxycholic bile acid was the predominant bile acid. Dietary bile acids supplementation also increased the proportion of T-BAs (tauro β-muricholic acid and taurodehydrocholic acid) while decreasing Free-BAs in the fish bile. In conclusion, the incorporation of cholesterol with bile acids into plant-based diets can effectively reduce cholesterol uptake, suppress bile acids synthesis, enhance bile acids efflux, and promote hepatocyte proliferation, which is helpful for maintaining the normal liver morphology in tilapia, and thus improving its growth performance.

中文翻译：

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通过在植物性饮食中补充胆固醇和胆汁酸，促进罗非鱼（Oreochromis niloticus）的生长、肝脏健康和胆汁酸代谢

本研究旨在比较植物性饮食中胆固醇、胆汁酸以及胆固醇与胆汁酸组合对转基因养殖罗非鱼幼鱼 (GIFT, ) 的营养影响。等氮（32 g/kg 粗蛋白）和异脂（76 g/kg 粗脂肪）日粮（Con 日粮）以植物蛋白来源为基础，包括玉米蛋白粉、豆粕、棉籽粕和菜籽粕。Con饮食分别补充12g/kg胆固醇（CHO饮食）、0.2g/kg胆汁酸（BAs饮食）、12g/kg胆固醇和0.2g/kg胆汁酸的组合（CHO-BAs饮食） 。将每种饲料喂入室内循环水产养殖系统的三个水箱中，持续 9 周。结果表明，与Con组相比，CHO-BAs组的鱼增重率、肝体指数较高，饲料转化率较低。对照组的全鱼脂肪和灰分含量最高。CHO、BAs 和 CHO-BAs 组的血清参数（包括丙氨酸转氨酶和天冬氨酸转氨酶的活性，以及​​除总胆固醇外的葡萄糖和甘油三酯水平）显着低于 Con 组。组织学检查显示Con组的鱼表现出严重的肝细胞空泡化和肝细胞增殖减少。基因表达分析表明，胆汁酸代谢相关基因（包括 、 、 ）的转录水平在 CHO-BAs 组中显着上调，而胆固醇代谢相关基因（ 和 ）在 CHO-BAs 组中显着下调。 CHO-BA 基团。此外，UPLC-MS/MS 分析表明，罗非鱼胆汁中牛磺酸结合胆汁酸 (T-BAs) 含量较高，其次是游离胆汁酸 (Free-BAs) 和甘氨酸 (G-BAs)。其中，牛磺鹅去氧胆汁酸是主要的胆汁酸。膳食胆汁酸补充剂还增加了 T-BA（牛磺β-鼠胆酸和牛磺脱氢胆酸）的比例，同时减少了鱼胆汁中的游离 BA。综上所述，在植物性日粮中添加胆固醇和胆汁酸，可以有效减少胆固醇摄取，抑制胆汁酸合成，增强胆汁酸外流，促进肝细胞增殖，有利于维持罗非鱼正常的肝脏形态，从而提高罗非鱼的肝脏功能。改善其增长绩效。