Hepatic transcriptome analyses of juvenile white bass (Morone chrysops) when fed diets where fish meal is partially or totally replaced by alternative protein sources

Authors: Fuller, Adam; Abernathy, Jason; SANKAPPA, NITHIN - Orise Fellow; Beck, Benjamin; Rawles, Steven - Steve; Green, Bartholomew - Bart; ROSENTRATER, KURT - Iowa State University; McEntire, Matthew - Matt; Huskey, George; Webster, Carl

Submitted to: Frontiers in Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2023
Publication Date: 1/15/2024
Citation: Fuller, S.A., Abernathy, J.W., Sankappa, N., Beck, B.H., Rawles, S.D., Green, B.W., Rosentrater, K.A., McEntire, M.E., Huskey Jr, G., Webster, C.D. 2024. Hepatic transcriptome analyses of juvenile white bass (Morone chrysops) when fed diets where fish meal is partially or totally replaced by alternative protein sources. Frontiers in Physiology. 14. Article 1308690. https://doi.org/10.3389/fphys.2023.1308690.
DOI: https://doi.org/10.3389/fphys.2023.1308690

Interpretive Summary: White bass (Morone chrysops; WB) are a popular sportfish throughout the southern United States, and one parent of the commercially-successful hybrid striped bass (M. chrysops x M. saxatilis; HSB). Commercial production of WB does not currently exist in the U.S. principally due to a lack of information regarding nutritional requirements, cost-effective diets, and production costs. Currently, WB are cultured using diets formulated for other carnivorous fish, such as largemouth bass (Micropterus salmoides) or HSB and contain a significant percentage of marine fish meal (FM). There is currently only one published report on the effects of diet formulation on growth and body composition of WB (data published from this Center). Since diets may exert a strong influence on gene expression of an organism, we conducted a gene expression analysis on WB which had been fed diets containing various percentages of marine fish meal. We found a total of 1563 genes expressed differently (DEGs) between all the comparisons, with the majority of these differences (95.9%) found in comparisons between the FM control and the no FM test diet or high soybean meal with the exception of the test diet containing high levels of poultry byproduct meal. Important metabolic genes involved in the regulation of glucose and fatty acid metabolism were differentially expressed with generally higher metabolic activity in fish reared on the FM control. Additionally, many genes involved in cellular stress, immune response, and apoptosis were differentially expressed with many unique signatures for each test diet, including the up regulation of immune response genes in many diets which could signal possible effects of anti-nutritional factors. These data will be impactful in determining the effects of diet formulation on WB so that an optimal diet can be fed to optimize health and growth of the fish.

Technical Abstract: White bass (Morone chrysops; WB) are a popular sportfish throughout the southern United States, and one parent of the commercially successful hybrid striped bass (M. chrysops x M. saxatilis; HSB). Commercial production of WB does not currently exist in the U.S. principally due to a lack of information regarding nutritional requirements, cost-effective diets, and production costs. Currently, WB are cultured using diets formulated for other carnivorous fish, such as largemouth bass (LMB; Micropterus salmoides) or HSB and contain a significant percentage of marine fish meal (FM). Since there are no studies regarding the utilization of alternative proteins in this species, we evaluated gene regulation of WB fed diets in which FM was partially or totally replaced by various combinations of soybean meal, poultry by-product meal, canola meal, soy protein concentrate, wheat gluten, or a commercial protein blend (Pro-Cision™). Six isonitrogenous (40% protein), isolipidic (11%), and isocaloric (17.1 kJ/g) diets were formulated to meet the known nutrient and energy requirements of LMB and HSB using nutrient availability data for most of the dietary ingredients. One of the test diets consisted exclusively of plant protein sources. Juvenile WB (40.2 g initial weight) were stocked into a flow-through aquaculture system (3 tanks/diet; 10 fish/tank) and fed the test diets twice daily to satiation for 60-d. We found a total of 1563 genes expressed differently (DEGs) between all the comparisons, with the majority of these differences (95.9%) found in comparisons between the FM control and the no FM test diet or high levels of soybean meal with the exception of the test diet containing high levels of poultry byproduct meal (Diet 4). Important metabolic genes involved in the regulation of glucose and fatty acid metabolism were differentially expressed with generally higher metabolic activity in fish reared on the FM control. Additionally, many genes involved in cellular stress, immune response, and apoptosis were differentially expressed with many unique signatures for each test diet, including the up regulation of immune response genes in many diets which could signal possible effects of anti-nutritional factors.