Dietary amino acid supplementation affects temporal expression of amino acid transporters and metabolic genes in selected and commercial strains of rainbow trout (oncorhynchus mykiss)

Authors: BREZAS, ANDREAS - University Of Idaho; Overturf, Kenneth - Ken; KUMAR, VIKAS - University Of Idaho; HARDY, RONALD - University Of Idaho

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2021
Publication Date: 2/28/2021
Citation: Brezas, A., Kumar, V., Overturf, K.E., Hardy, R. 2021. Dietary amino acid supplementation affects temporal expression of amino acid transporters and metabolic genes in selected and commercial strains of rainbow trout (oncorhynchus mykiss). Aquaculture. 255. Article 110589. https://doi.org/10.1016/j.cbpb.2021.110589.
DOI: https://doi.org/10.1016/j.cbpb.2021.110589

Interpretive Summary: Replacement of fishmeal as the major protein source in feeds is critical for continued growth and sustainability of the aquaculture industry. However, numerous studies have shown suboptimal fish growth performance when carnivorous fish species are fed low fishmeal-high plant protein feeds. In this study we looked to compare a commercial strain and a genetically improved strain of rainbow trout selected for improved performance when fed an all plant protein diet, identifying physiological differences associated with growth performance in the selected trout strain. Fish from both strains were force-fed a plant-protein blend with and without amino acid supplementation. Tissue samples were then analyzed for specific gene expression analysis related to metabolism. The results provide evidence that improved growth and protein retention of the selected strain fed an all-plant protein diet is a result of nutritional adaptation and an overall different physiological homeostatic control.

Technical Abstract: Replacement of fishmeal as the major protein source in feeds is critical for continued growth and sustainability of the aquaculture industry. However, numerous studies have shown suboptimal fish growth performance and reduced protein retention efficiency when carnivorous fish species are fed low fishmeal-high plant protein feeds. A study was conducted using a commercial strain and a genetically improved strain of rainbow trout selected for improved performance when fed an all plant protein diet, identifying physiological differences associated with growth performance in the selected trout strain. Fifty individuals per strain (average weight ~580g) were force-fed a plant-protein blend with and without amino acid supplementation (Lys, Met and Thr) at 0.5% body weight and sampled at intervals over 24h. Samples from intestine, liver and muscle were analyzed for specific gene expression analysis related to amino acid transporters, digestive process control, protein degradation and amino acid metabolism. The results showed that expression levels of various intestinal amino acid transporters (SLC1A1, SLC7A9, SLC15A, SLC1A5 SLC6A19 and SLC36A1) were affected by strain, diet and time. Moreover, significant interactions were found regarding the temporal expression levels of cholecystokinin (CCK-L), Krüppel-like factor 15 (KLF15), autophagy-related 4B cysteine peptidase (ATG4b) and aspartate aminotransferase (GOT) transcripts in the examined tissues. The results provide evidence that improved growth and protein retention of the selected strain fed an all-plant protein diet is a result of nutritional adaptation and an overall different physiological homeostatic control.