Integrated alternative approaches to select feed-efficient rainbow trout families to enhance the plant protein utilization

Authors: KAJBAF, KIMIA - University Of Idaho; Overturf, Kenneth - Ken; KUMAR, VIKAS - University Of Idaho

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2024
Publication Date: 2/16/2024
Citation: Kajbaf, K., Overturf, K.E., Kumar, V. 2024. Integrated alternative approaches to select feed-efficient rainbow trout families to enhance the plant protein utilization. Scientific Reports. 14. Article 3869. https://doi.org/10.1038/s41598-024-54218-2.
DOI: https://doi.org/10.1038/s41598-024-54218-2

Interpretive Summary: Aquaculture is the fastest growing sector of animal agriculture. Aquaculture has been continually growing for the past several decades, however while initial and current feeds mainly utilize fishmeal as the primary dietary protein, source this is now proving unsustainable. Therefore, it is necessary to develop feeds that utilize alternative sources of protein and fish that can more efficiently process and utilize dietary protein. This study evaluated rainbow trout that had gone through two feeding and growth trials in which the fish were subjected to long-term feed deprivation followed by ad libitum feeding. From this study it was shown that the fish that lost the least amount of weight during feed deprivation and gained the most weight during satiation refeeding also exhibited the lowest feed conversion ratios. These findings suggest that it should be possible to genetically improve feed efficiency in rainbow trout. Aquaculture producers are in dire need of fish that utilize feed as efficiently as possible to reduce feed costs and reduce wastes from production facilities that passes to downstream receiving waters.

Technical Abstract: Improving feed utilization efficiency is a challenge in aquaculture. Therefore, we developed an indirect benchmark to use in selecting trout for improved efficiency of feed utilization on plant protein (soy)-based diets, with the long-term goal of reducing the cost of commercial trout production. We used a four-part integrative approach to identify feed efficient individuals among 1595 fish coming from 12 genetically selected families by establishing the phenotypic relationship between feed conversion ratio (FCR) and body weight variations using compensatory feeding regimes. Additionally, we examined the nutritional composition of fish filet for each efficiency phenotype during the compensatory regimen. Our findings showed that the fish with the lowest weight loss during a feed deprivation period and the highest weight gain during the refeeding (FD-/RF+) demonstrated the lowest FCR (FCR=0.99) and consisted of individuals from several lines. This finding confirms the possibility of improving feed efficiency in mixed lines. Although feeding period has an effect on nutritional composition of fillet, such selection criteria did not show an effect on groups. Overall, successful selection for the improvement of feed efficiency will have a broad application to commercial fish selective breeding programs, leading to increased aquaculture sustainability in the long run.