Digesta and plasma metabolomics of rainbow trout strains with varied yolerance of plant-based diets highlights potential for non-lethal assessments of enteritis development

Authors: PALMA, MARIANA - University Of Coimbra; Bledsoe, Jacob; TAVARES, LUDGERO - University Of Coimbra; ROMANO, NICHOLAS - University Of Arkansas At Pine Bluff; SMALL, BRIAN - University Of Idaho; VIEGAS, IVAN - University Of Coimbra; Overturf, Kenneth - Ken

Submitted to: Metabolites
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2021
Publication Date: 9/1/2021
Citation: Palma, M., Bledsoe, J.W., Tavares, L.C., Romano, N., Small, B., Viegas, I., Overturf, K.E. 2021. Digesta and plasma metabolomics of rainbow trout strains with varied yolerance of plant-based diets highlights potential for non-lethal assessments of enteritis development. Metabolites. 11(9). Article 11090590. Available: https://doi.org/10.3390/metabo11090590.
DOI: https://doi.org/10.3390/metabo11090590

Interpretive Summary: The replacement of fishmeal, as a protein source in aquaculture feeds is essential to the sustainability of the industry. A concerted effort has been in place to replace fishmeal with sustainable proteins derived from plants. However, several serious issues have arisen when replacing fishmeal with plant-derived proteins in aquafeeds including, reduced growth, increased mortality and harmful waste passed to downstream systems, and intestinal impairment also known as enteritis. Besides the procurement of alternative protein sources, fish can also be selected for better performance on sustainable alternative diets utilizing plant proteins in place of fishmeal. Rainbow trout is one such species in which a strain, termed ARS-Sel, has been selected for higher growth and enhanced utilization when fed diets where fishmeal has been replaced with soybeans as the protein source and does not present with enteritis when fed a diet formulated with fishmeal completely replaced with plant proteins. This study attempted to evaluate the metabolome, the complete set of small-molecule chemicals found within a biological sample, in non-lethally obtained samples to determine if they could be useful in determining the onset of enteritis. The metabolome of plasma and digesta from a commercial strain was evaluated alongside the ARS-Sel strain on both a fishmeal and a plant protein based diet to determine if the metabolome could be used to follow the onset of enteritis in commercial lines of fish reared on plant based feeds. Our results show that metabolome differences were detected between the treatments and could prove useful in evaluating different plant based proteins for use in aquafeeds.

Technical 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.