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Gossypol, a naturally occurring compound found in cottonseed meal, shows promising therapeutic potential for human diseases. However, within the aquaculture industry, it is considered an antinutritional factor. The incorporation of cottonseed meal into fish feed introduces gossypol, which induces intracellular stresses and hinders overall health of farmed fish. The aim of this study is to determine the role of General control nonderepressible 2 (gcn2), a sensor for intracellular stresses in gossypol-induced stress responses in fish. In the present study, we established two gcn2 knockout zebrafish lines. A feeding trial was conducted to assess the growth-inhibitory effect of gossypol in both wild type and gcn2 knockout zebrafish. The results showed that in the absence of gcn2 , zebrafish exhibited increased oxidative stress and apoptosis when exposed to gossypol, resulting in higher mortality rates. In feeding trial, dietary gossypol intensified liver inflammation in gcn2 −/− zebrafish, diminishing their growth and feed conversion. Remarkably, administering the antioxidant N-acetylcysteine (NAC) was effective in reversing the gossypol induced oxidative stress and apoptosis, thereby increasing the gossypol tolerance of gcn2 −/− zebrafish. Exposure to gossypol induces more severe mitochondrial stress in gcn2 −/− zebrafish, thereby inducing metabolic disorders. These results reveal that gcn2 plays a protective role in reducing gossypol-induced oxidative stress and apoptosis, attenuating inflammation responses, and enhancing the survivability of zebrafish in gossypol-challenged conditions. Therefore, maintaining appropriate activation of Gcn2 may be beneficial for fish fed diets containing gossypol. • Zebrafish lacking Gcn2 showed a significant increase in mortality when exposed to gossypol. • Gcn2 deficiency exacerbated oxidative stress and apoptosis in response to gossypol exposure. • Zebrafish deficient in Gcn2 exhibited more severe liver inflammation upon dietary gossypol exposure. [ABSTRACT FROM AUTHOR]

Soybean meal is one of the most promising alternatives to replace fishmeal in the aquaculture industry. However, its ingestion triggers an intestinal inflammatory process that compromises fish health and nutrition. Therefore, finding strategies that reduce the deleterious effects of a soy protein-based diet are relevant. In this work we analyzed the effects of an aloe vera (Aloe barbadensis miller, AV) extract on intestinal inflammation and innate immunity of zebrafish by adding it to the water and by supplementing it in a soybean meal-based diet. To search for potential immunomodulatory effects of AV, we tested its effectiveness in two inflammation assays and compared fish fed with either fishmeal or soybean meal-based feed supplemented with AV. Our results show a strong anti-inflammatory effect of AV. Furthermore, while soy-based meal strongly induces the expression of inflammation markers, supplementation with AV reverted this effect. Finally, we show that fish fed with a soy meal diet are highly susceptible to bacterial infection, but that this condition is significantly reduced when the soy meal is supplemented with AV. Our results suggest that AV is a good candidate to be incorporated as an additive in farmed fish diets to facilitate the replacement of fishmeal by soybean meal, maintaining intestinal health. • Aloe vera added to a soybean meal-based diet prevented the induction of intestinal inflammation caused by this food. • Aloe vera exerts anti-inflammatory effects preventing neutrophil migration and the generation of pro-inflammatory signals. • Aloe vera, incorporated in the diet, exerts an antioxidant effect. • Aloe vera does not exert an immunostimulatory effect, nor added in the diet neither to the medium. [ABSTRACT FROM AUTHOR]

Abstract A 12-week feeding trial was conducted to evaluate the effects of dietary sodium butyrate (NaBT) on the intestinal health of juvenile turbot (Scophthalmus maximus L.), in terms of inflammatory status, mucosal barriers and microbiota. Three isonitrogenous and isolipidic practical diets were used: (1) fish meal based group (FM); (2) soybean meal group (SBM), soy protein replacing 40% fish meal protein in FM; (3) NaBT group, 0.2% NaBT supplemented in SBM. Each diet was fed to triplicate tanks (30 fish in each tank). The current results showed that 0.2% dietary NaBT improved the growth performance of fish and alleviated the enteropathy, increasing the absorptive surface and mitigating the infiltration of mixed leukocytes in lamina propria. Fish fed the NaBT diet presented increased activities of intestinal brush border enzyme and similar nutrient digestibility with the FM group. Compared to SBM, the inclusion of 0.2% NaBT in diet significantly up-regulated the intestinal gene expression of tight junction proteins and down-regulated the gene expression of TNF-α and NF-κB. The gut microbial communities of the NaBT group were closer to the FM group than to the SBM group, in terms of PCoA, UPGMA and Heatmap analyses based on weighted Unifrac distance. The relative abundance of several dominant bacteria at the phylum (Proteobacteria, Bacteroidetes, Deinococcus-Thermus and Actinobacteria) and genus level (Thermus , Acinetobacter , Bacteroides and Silanimonas) were altered by dietary NaBT. In conclusion, dietary NaBT had positive roles in protecting the intestinal health of turbot from the impairment of soybean meal. Highlights • Supplementing 0.2% dietary NaBT could alleviate soybean-induced enteropathy of turbot. • NaBT enhanced intestinal mucosal tight junction and relieved inflammation of turbot. • NaBT in diet led to closer intestinal microbial composition to the fish fed fish meal. [ABSTRACT FROM AUTHOR]

Abstract This study examined the effects of replacing fish meal (FM) with three different types of soybean meal (SM) including untreated SM, Bacillus pumillus SE5 (BP) fermented SM (BPFSM) and Pseudozyma aphidis ZR1 (PA) fermented SM (PAFSM) in diets for Japanese seabass (Lateolabrax japonicus). A basal diet was formulated using FM (FM diet), and six other diets were produced by substituting 40 or 80% of FM with SM, BPFSM or PAFSM (SM40, SM80, BPFSM40, BPFSM80, PAFSM40 and PAFSM80 diets). Each diet was fed to triplicate groups of fish (7.14 ± 0.05 g) twice daily for eight weeks. Replacing 40% of FM with SM sources did not significantly influence growth (P > 0.05), while increasing the substitution level to 80% led to reduced growth rates (P < 0.05). The groups received SM80 and PAFSM80 diets showed significantly higher feed conversion ratio and lower protein digestibility than FM group. Furthermore, notably lower dry matter digestibility was detected in SM80 group. Remarkably lower serum total antioxidant capacity was found in the SM80 group, and catalase activity did not significantly differ between FM and BPFSM40 groups. Serum malondialdehyde concentration was enhanced by increasing FM replacement level and the highest value was observed in the SM80 fed fish. FM and PAFSM40 groups showed significantly higher lysozyme activity than the SM80 group. Fish fed the BPFSM40 diet exhibited the highest complement C3 activity and the lowest value was observed in the SM80 group. Expression of lysozyme gene in spleen was down-regulated in the SM80 group, and no significant difference in expression of C3 gene was found among FM, BPFSM40 and PAFSM40 groups. Digestive enzymes activity and gut morphology were significantly influenced by FM replacement. Expression of HSP70 and pro-inflammatory genes including TNF-α and IL-1β were up-regulated by FM replacement and relatively lower expression levels were found by using fermented SM. An opposite trend was observed for the anti-inflammatory TGF-β gene expression. Serum d -lactate concentration was significantly increased by replacing 80% of FM with any of the SM sources. These findings indicated that using fermented SM, particularly BPFSM, beneficially influences feed utilization, antioxidant capacity, innate immunity and gut health in juvenile Japanese seabass. Highlights • Yeast and bacterial fermented soybean meal were tested in Japanese seabass feed. • Fermentation with Bacillus pumillus SE5 improved digestibility of soybean meal. • Fermented soybean meal enhanced antioxidant capacity and innate immune response. • Fish meal replacement with soybean meal suppressed digestive enzymes activity. • Fermentation of soybean meal ameliorated the damaging effects on gut structure. [ABSTRACT FROM AUTHOR]

One of the most important routes for human exposure to polybrominated diphenyl ethers (PBDEs) is the ingestion of contaminated food. Food of animal origin safety is strongly related to feed quality. The aim of the study was the assessment of feeds and feed materials quality associated with ten PBDE congeners (BDE-28, 47, 49, 99, 100, 138, 153, 154, 183 and 209) contamination. The quality of 207 feed samples divided into eight categories (277/2012/EU) was checked using the gas chromatography–high resolution mass spectrometry (GC-HRMS). At least one congener was identified in 73% of the samples. All investigated fish oil, animal fat, and feed for fish were contaminated, and 80% of plant-origin feed samples were free of PBDEs. The highest median content of ∑ 10 PBDE was found in fish oils (2260 ng kg−1) followed by fishmeal (530 ng kg−1). The lowest median was found in mineral feed additives, plant materials excluding vegetable oil and compound feed. BDE-209 was the most frequently detected congener (56%). All congeners except BDE-138 and BDE-183 were detected in 100% of the fish oil samples. Except for BDE-209, the congener detection frequencies did not exceed 20% in compound feed, feed of plant origin, and vegetable oils. Excluding BDE-209, similar congener profiles were found for fish oils, fishmeal and feed for fish, with BDE-47 in the highest concentration, followed by BDE-49 and BDE-100. Another pattern appeared in animal fat, with a higher median concentration of BDE-99 than BDE-47. Time-trend analysis of PBDE concentrations in fishmeal (n = 75) showed a 63% decrease in ∑ 10 PBDE (p = 0.077) and a 50% decrease in the ∑ 9 PBDE (p = 0.008) between 2017 and 2021. It proves the international legislation implemented to reduce PBDE environmental levels has been effective. [Display omitted] • PBDE concentrations in various feed categories are presented. • PBDEs were omnipresent in feeds from Poland. • 100% of marine-origin and 20% of plant-origin feeds were polluted. • Characteristic congener profiles in feeds were observed. • PBDE levels in fishmeal significantly decreased during 2017–2021. [ABSTRACT FROM AUTHOR]

The nematodes Anisakis simplex and Pseudoterranova decipiens , are zoonotic parasites infecting many marine fish and pose a substantial human health risk. Besides being causative agents for gastrointestinal disease after ingestion of a live larva, and an allergic reaction after consuming/handling infected fish, there is proof-of-principle for hidden allergic concerns. Several anisakid allergens are highly resistant, and in this way may be transmitted to meat by use of fishmeal as a feed component for livestock. To consolidate this hypothesis of transmissibility, a controlled chicken feeding trial using Anisakidae-contaminated feed was conducted. Anisakid larvae were collected from codfish and freeze-dried according to fishmeal manufacturing conditions. This larvaemeal was then administered to chickens, and after three weeks of exposure, blood and muscle samples were subjected to a targeted proteomic analysis aiming at detecting anisakid peptides. Results demonstrated that peptides from at least six A. simplex allergens were transferred from the feed to the chicken meat and blood. If future experiments confirm a remaining allergenic potency of these peptides in humans, it would significantly change the importance of these zoonotic nematodes from originally a purely fishborne food risk to potentially a wider risk from several food sources. • Many Anisakis allergens are highly resistant to heating, freezing, and digestion. • Anisakis and Pseudoterranova L3 are present in fish typically converted into fishmeal. • Fishmeal is included in foods for the aquaculture, pig, and poultry sector. • Anisakis allergenic peptides are transferred from animal feed to chicken meat. [ABSTRACT FROM AUTHOR]

Fish meal and fish oil represent main protein and lipid sources in fish feed, but there is a growing need for sustainable alternatives to these ingredients. In this study, four isolipid extruded diets for carp ( Cyprinus carpio L.) were used: ROHP (rapeseed oil-high protein), FOHP (fish oil-high protein); ROLP (rapeseed oil-low protein) and FOLP (fish oil-low protein). The trial lasted 75 days. No statistically significant effect of oil source or protein level or interactions of these factors was observed in final body weight, growth parameters or in feed conversion ratio. Protein sparing effect and omega-3 sparing effect were observed in the present study. The results of this experiment showed no negative effects on growth parameters, or major detrimental effects on fatty acid composition of muscle tissue in common carp when fish fed with diets supplemented with rapeseed oil (RO). Furthermore, an enhanced protein sparing effect was observed, when fish fed with lower protein diets, but significant accumulation of crude lipid was observed as a result of lowering protein level. The results of this study showed that diets supplemented with rapeseed oil can be used successfully in common carp cage production. [ABSTRACT FROM AUTHOR]

The Bokashi leachate (BL) is a by-product from the anaerobic digestion of food waste, following the Bokashi composting method. Bokashi leachate is acidic and it contains effective microorganisms hence it has potential to be a functional feed additive to the plant proteins based diets for fish farming. This study evaluated the growth performance and feed utilization of the red tilapia (Oreochromis sp.) fingerlings fed with the BL supplemented soybean meal (SBM) based diets. After an 8-week feeding trial, fish fed with the 5% BL supplemented SBM diet attained the highest weight gain. This result was significantly higher (p < 0.05) than those fed with the 0% BL supplemented SBM diet, and comparable (p > 0.05) to those fed with the control full fish meal (FM) diet. Generally, dietary inclusion of BL enhanced the fish feed intake on the SBM diet but it did not show clear sign of improvement in their feed utilization. In addition, no significant difference was found across the hepatosomatic index and viscerosomatic index from all dietary treatments. These outcomes concluded that dietary inclusion of BL can enhance the feed intake and growth performance of the red tilapia fingerlings fed with the SBM based diet without compromising their health, and the optimum BL inclusion level was 5%. Nevertheless, further study on the properties and substances content of the BL produced from different types and ratios of food waste is strongly recommended. In this study, BL was also discovered to be capable of reducing the crude fiber content in the SBM diets. Such observation deserves a further exploitation on the application of BL to manipulate the crude fiber content in the plant proteins based diets in fish farming. • First study to exploit the potential usage of Bokashi leachate (BL) in fish farming. • BL dietary inclusion enhanced growth of tilapia fed soybean meal (SBM) based diet. • Growth of fish fed BL added diet was comparable to that fed fish meal based diet. • BL inclusion reduced the crude fiber content of SBM diets. • This study has achieved the goal of "Turning Waste to Gold". [ABSTRACT FROM AUTHOR]