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

<p>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 (<em>Oncorhynchus mykiss</em>) is one such species in which the strain ARS-<em>Sel</em>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 the ARS-<em>Sel</em>and two commercial strains (CS-1 and CS-2), when fed a plant-protein diet (PM) and a fishmeal-based diet (FM) and 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-<em>Sel</em>fish receiving the PM diet reaching the highest final weight at sampling. Multivariate analysis revealed differences between plasma metabolite profiles of ARS-<em>Sel</em>and CS (CS-1 considered together with CS-2) PM-fed groups in the early stages of the enteritis development, which was confirmed by a histological approach. In digesta, no differences were observed between groups. As reported in previous studies the ARS-<em>Sel</em>strain performed better than the commercial strains when fed the PM diet.&nbsp;</p>