Corn gluten meal induces enteritis and decreases intestinal immunity and antioxidant capacity in turbot (Scophthalmus maximus) at high supplementation levels

Abstract

Corn gluten meal (CGM) is an important alternative protein source in aquafeed production. However, in turbot (Scophthalmus maximus), CGM could not be effectively utilized because of its low digestibility, the reason for which is still unclear. The purpose of the present study was to investigate and elucidate the cause for the poor utilization of CGM by turbot from the view of gut health. An 8-week feeding trial was conducted with turbot individuals (initial body weight 11.4 ± 0.2 g), which were fed with one of four isonitrogenous and isolipidic diets formulated to include 0%, 21.2%, 31.8%, and 42.6% CGM to progressively replace 0%, 33%, 50%, and 67% fish meal (FM) protein in a FM-based diet, respectively. The results showed that CGM caused dose-dependent decreases in (1) growth performance, nutrient digestibility, and feed utilization; (2) activities of brush-border membrane enzymes; (3) intestinal antioxidant indices of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase activities, and reduced glutathione level; (4) intestinal immune parameters of acid phosphatase activity, complement 3, complement 4, and IgM concentrations. Dose-dependent increases in the severity of the inflammation, with concomitant alterations on microvilli structure and increasing expression of inflammatory cytokine genes of Il-1β, Il-8, and Tnf-α were observed but without a change in the intracellular junctions and the epithelial permeability established by the plasma diamine oxidase activity and D-lactate level examinations. In conclusion, the present work proved that CGM negatively affected the gut health of turbot by inducing enteritis and by decreasing intestinal immunity and antioxidant capacity, which could be one of the reasons for the reduced utilization of CGM by turbot.

Intestinal Transcriptome Analysis Highlights Key Differentially Expressed Genes Involved in Nutrient Metabolism and Digestion in Yellowtail Kingfish (Seriola lalandi) Fed Terrestrial Animal and Plant Proteins

“…Interestingly, no significantly differentially expressed transcripts involved in inflammation were found in the RNA-Seq results, which support the lack of histological abnormality in this study. This result contrasts with studies on California yellowtail, S. dorsalis [23], Atlantic salmon, S. salar [28,46] and turbot, Scophthalmus maximus [47]. The differences with our finding might be related to the longer trial duration in those studies (56 days to 96 days) or the varying response in different species.…”

Effects of partial replacement of dietary fish meal by bioprocessed plant protein concentrates on growth performance, hematology, nutrient digestibility and digestive enzyme activities in juvenile Pacific white shrimp, Litopenaeus vannamei

“…Corn gluten meal (CGM) is a good source of protein having at least 63% protein and low fat which has been used for its beneficial effects as a source of protein in the diet of Pacific white shrimp . CGM is an important protein part obtained from the wet milling process for the isolation of the starch, germ, protein and fiber components of corn . However, as a plant protein, CGM also contains some ANFs and limiting amino acids .…”

European seabass (Dicentrarchus labrax) performance, health status, immune response and intestinal morphology after feeding a mixture of plant proteins-containing diets

“…Proximal portion of fish intestine (PI) is credited with higher nutrients digestibility and absorption and overall digestive capacity (Krogdahl et al, 2003). It is well documented that the anti-nutritional factors present in soybean products and/or CG can cause moderate or severe enteritis in European seabass (Cuoto et al, 2015, Rimoldi et al, 2016, Bai et al, 2019. In the present study, although no overt inflammation was observed, fish fed the lowest FM level (20%) presented some alterations in their PI morphological structure when compared with fish fed the CTRL or other PX diets (Fig 2A-C).…”

“…However, there are still apparent and unidentified biologically active compounds in plant products that inhibit the complete replacement of FM in carnivorous fish feeds (Gatlin et al, 2007;Glencross, 2016). Although these plant protein ingredients are among the most commonly used for FM replacement in fish feeds, their use in salmonid, European seabass, gilthead seabream and turbot feeds is limited due to the development of induced inflammation in the distal intestine (enteritis) of these fish (Kokou et al, 2015;Rimoldi et al, 2016;Bai et al, 2019).…”

“…Histological characteristics of the fish intestine have been used to analyse functional mechanisms that are helpful in diagnosing intestinal diseases and formulating suitable feeds (Khojasteh 2012). Nevertheless, there have been few studies examining the influence of combined dietary SBM, SPC and/or CG on seabass health status, immune-competence and intestinal histomorphology (Bonaldo et al 2008;Rimoldi et al 2016;Wassef et al 2016Wassef et al , 2019Bai et al, 2019), and the results have not been consistent.…”