Table1_Efficacy of Utilization of All-Plant-Based and Commercial Low-Fishmeal Feeds in Two Divergently Selected Strains of Rainbow Trout (Oncorhynchus mykiss): Focus on Growth Performance, Whole-Body Proximate Composition, and Intestinal Microbiome.docx

The present study aimed to investigate the growth performance, whole-body proximate composition, and intestinal microbiome of rainbow trout strains when selected and non-selected for weight gain on all-plant protein diets. A 2x2 factorial design was applied, where a selected (United States) and a non-selected (ITA) rainbow trout strain were fed using either an all-plant protein (PP) or a commercial low-FM diet (C). Diets were fed to five replicates of 20 (PP) or 25 (C) fish for 105 days. At the end of the trial, growth parameters were assessed, and whole fish (15 pools of three fish/diet) and gut samples (six fish/diet) were collected for whole-body proximate composition and gut microbiome analyses, respectively. Independent of the administered diet, the United States strain showed higher survival, final body weight, weight gain, and specific growth rate when compared to the ITA fish (p < 0.001). Furthermore, decreased whole-body ether extract content was identified in the PP-fed United States rainbow trout when compared to the ITA strain fed the same diet (p < 0.001). Gut microbiome analysis revealed the Cetobacterium probiotic-like genus as clearly associated with the United States rainbow trout, along with the up-regulation of the pathway involved in starch and sucrose metabolism. In summary, the overall improvement in growth performance and, to a lesser extent, whole-body proximate composition observed in the selected rainbow trout strain was accompanied by specific, positive modulation of the intestinal microbiome.

本研究旨在探究全植物蛋白日粮（all-plant protein diets）条件下，针对增重性状选育与未选育的虹鳟品系的生长性能、全鱼常规营养组成及肠道微生物组（gut microbiome）特征。本研究采用2×2析因试验设计，选取针对增重选育的美国品系虹鳟与未选育的ITA品系虹鳟，分别饲喂全植物蛋白日粮（简称PP）或商业低鱼粉日粮（commercial low-FM diet，简称C）。每组设置5个重复，PP组每个重复放养20尾鱼，C组每个重复放养25尾鱼，试验周期为105天。试验结束后，测定各组生长参数，并分别采集全鱼样本（每个日粮组制备15个混合样本，每个样本含3尾鱼）与肠道样本（每个日粮组采集6尾鱼），用于全鱼常规营养组成分析与肠道微生物组分析。无论饲喂何种日粮，美国选育品系虹鳟的存活率、终末体重、增重率与特定生长率均显著高于ITA品系（p < 0.001）。此外，饲喂全植物蛋白日粮时，美国选育品系虹鳟的全鱼乙醚浸出物（ether extract）含量显著低于同日粮饲喂的ITA品系（p < 0.001）。肠道微生物组分析显示，类益生菌鲸杆菌属（Cetobacterium）与美国选育品系虹鳟显著相关，其肠道内淀粉与蔗糖代谢通路亦呈现上调趋势。综上，选育虹鳟品系的生长性能得到全面提升，全鱼常规营养组成也得到一定程度改善，同时伴随肠道微生物组的特异性正向调控。