Digesta and Plasma Metabolomics of Rainbow Trout Strains with Varied Tolerance of Plant-Based Diets Highlights Potential for Non-Lethal Assessments of Enteritis Development.

Mariana Palma,Brian C Small,Jacob W Bledsoe,Ludgero C Tavares,Ivan Viegas,Ken Overturf,Nicholas Romano

doi:10.3390/metabo11090590

Abstract

The replacement of fishmeal in aquafeeds is essential to the sustainability of aquaculture. Besides the procurement of alternative protein sources, fish can also be selected for better performance on plant-based alternative diets. Rainbow trout (Oncorhynchus mykiss) is one such species in which the strain ARS-Sel has been selected for higher growth and enhanced utilization when fed soy-based diets. The aim of this study was to compare fish growth and plasma and digesta metabolomes between ARS-Sel and two commercial strains (CS-1 and CS-2), when fed plant-protein (PM) and fishmeal-based (FM) diets, and to correlate them with the onset of enteritis. An NMR-metabolomics approach was taken to assess plasma and digesta metabolite profiles. Diet and strain showed significant effects on fish growth, with the ARS-Sel fish receiving the PM diet reaching the highest final weight at sampling. Multivariate analysis revealed differences between plasma and digesta metabolite profiles of ARS-Sel and CS (CS-1 considered together with CS-2) PM-fed groups in the early stages of enteritis development, which was confirmed by intestinal histology. As reported in previous studies, the ARS-Sel strain performed better than the commercial strains when fed the PM diet. Our findings also suggest that metabolomic profiles of plasma and digesta, samples of which can be obtained through non-lethal methods, offer valuable insight in monitoring the occurrence of enteritis in carnivorous aquaculture species due to plant-based diets.

Highlights

IntroductionWhile finfish aquaculture continues to develop and grow, its growth has been limited partially due to the reliance of fishmeal as a primary protein source in aquaculture feeds
Aquaculture continues to be the most rapidly expanding form of animal agriculture
Our approach compared the growth performance and Nuclear Magnetic Resonance (NMR) metabolome profiles of rainbow trout selected for plant-based diet utilization to commercial controls using biological materials which can be collected using non-lethal sampling techniques, while confirming phenotypic differences in dietary response using traditional histological analysis

Summary

Introduction

While finfish aquaculture continues to develop and grow, its growth has been limited partially due to the reliance of fishmeal as a primary protein source in aquaculture feeds. Several serious issues have arisen when replacing fishmeal with plant-derived proteins in aquafeeds, including reduced growth, increased mortality and effluent waste, intestinal inflammation, and chronic immune stimulation [7,8,9,10]. Selection in aquaculture species has mainly been driven towards the main production traits such as growth, disease resistance, feed intake, feed efficiency [12,13], and fillet features like yield [14], and fat content [15,16]. The advances brought by this type of strategy underpin its feasibility to generate cohorts of individuals potentially more adapted to feeds with increased plant-protein contents

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