The Future of Aquatic Protein: Implications for Protein Sources in Aquaculture Diets

Optimizing reproductive performance in pangasius catfish broodstock: A review of dietary and molecular strategies

Pangasius catfish, a significant player in the global whitefish market, encounters challenges in aquaculture production sustainability. Quality broodstock maintenance and seed production are impeded by growth, maturation, and fecundity issues. This review investigates the efficacy of strategic nutrient composition and molecular strategies in enhancing broodstock conditions and reproductive performance across various fish species. A notable knowledge gap for Pangasius catfish hampers aquaculture progress. The review assesses nutrient manipulation's impact on reproductive physiology, emphasizing pangasius broodstock. A systematic review analysis following PRISMA guidelines was conducted to identify research trends and hotspots quantitatively, revealing a focus on P. bocourti and fertilization techniques. Addressing this gap, the review offers insights into dietary nutrients manipulation and genetic tool utilization for improved seed production, contributing to pangasius catfish aquaculture sustainability.

Exploring the variations in molecular characteristics of dissolved organic matter driven by aquaculture types

In recent decades, global aquaculture has expanded rapidly, raising concerns about coastal environmental degradation due to unregulated or poorly regulated discharge of aquaculture tailwater. Despite the crucial role of dissolved organic matter (DOM) in biogeochemical processes and aquatic biodiversity, the influence of aquaculture type on the molecular characteristics of DOM remains largely unexplored. Herein, this study investigated the variations in chemical and spectroscopic properties as well as molecular characteristics and composition of DOM across different aquaculture types including crustacean, fish and shellfish. Our findings revealed notable differences in DOM quantities among different aquaculture types, with crustacean and fish aquaculture water containing higher DOM amount compared to shellfish aquaculture water. This disparity can be attributed to the more frequent formulated feeds of crustacean and fish in contrast to shellfish aquaculture. Furthermore, distinct differences were also observed in the characteristics and composition of DOM among the different aquaculture waters. Specifically, DOM in shellfish aquaculture water exhibited a higher abundance of unsaturated and reduced molecules as well as increased aromaticity compared to the other two aquaculture waters. Conversely, DOM from fish aquaculture water showed a greater contribution from terrestrial origin characterized by elevated levels of plant-based components such as lignin-like and tannin-like compounds. Interestingly, DOM from shellfish aquaculture water contained lower levels of microbial-derived components such as lipid-like and protein-like compounds, likely due to reduced microorganism populations resulting from lower nutrients availability and higher salinity. Overall, these significant variations in characteristics and composition of DOM underscore the potential impacts of aquaculture type on the DOM biogeochemical cycle and the environmental quality in aquatic ecosystems.

Retention of prions in the polychaete Hediste diversicolor and black soldier fly, Hermetia illucens, larvae after short-term experimental immersion and feeding with brain homogenate from scrapie infected sheep

Finding alternative protein and lipid sources for aquafeeds is crucial for the sustainable growth of fed aquaculture. Upcycling industrial side streams and byproducts using extractive species can reduce waste and help reduce the sector's dependence on fish meal and fish oils. Polychaete worms (Hediste diversicolor) and black soldier fly (Hermetia illucens) larvae (BSFL) are promising candidates for converting waste materials into valuable protein and lipid sources. However, further research and evaluations are needed to ensure the safety and regulatory compliance of these alternative feed sources, especially regarding prions spreading potential in the unlikely case that prions would be introduced in the value chain via feedstocks. In the present investigation, BSFL and juvenile polychaetes that had received a massive dose of scrapie prions through immersion and oral inoculation were found to harbour detectable prions using an ultrasensitive amplification method known as PMCA. This observation suggests that both H. diversicolor and BSFL have the potential to serve as mechanical vectors for prions diseases. However, it is important to note that insects, lacking the prion protein gene, are incapable of propagating prions. Therefore, the quantity of prions present in the larvae will inevitably be lower than the amount of prions they encountered. This is the first study to report on the fate of prions through ingestion by these marine and terrestrial invertebrate species.

Evaluation of four novel non-grain protein sources completely replacing soybean meal on growth performance, serum biochemistry, amino acid transport and intestinal health of grass carp (Ctenopharyngodon idella) at different water temperatures

To investigate the effects of non-grain protein source and water temperature on growth and feed utilization differences of grass carp, the effects of different protein sources on the growth performance, serum biochemistry, digestive enzymes, amino acid transport and intestinal health of grass carp were studied at 24 °C, 28 °C and 32 °C. In this study, a total of 1350 grass carp (Ctenopharyngodon idella) (initial weight 5.00 ± 0.02 g) were selected, and Clostridium autoethanogenum protein (CAP), Tenebrio molitor meal (TMM), cottonseed protein concentrate (CPC) and Chlorella powder (CHP) were used as a single protein source to completely replace soybean meal for 56 days. The results showed that the final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and protein efficiency ratio (PER) of grass carp increased significantly with the increasing temperature (P < 0.001). The CHP and SBM groups showed no significant differences in FBW, WGR, SGR and PER (P > 0.05), which were higher than the CAP, TMM and CPC groups (P < 0.001). The alanine transaminase (ALT), aspartate aminotransferase (AST), total protein (TP) and triglyceride (TG) concentrations of grass carp at 32 °C were significantly lower than those at 24 °C and 28 °C (P < 0.001). The acid phosphatase (ACP) activity decreased significantly with the increase of temperature (P = 0.001). The amylase (AMS) activity of the TMM, CPC and CHP groups was significantly lower than that of the SBM and CAP groups (P < 0.001), and the ACP and lipase (LPS) activities in the TMM group were significantly lower than those in the SBM group (P < 0.001). In addition, the interaction between temperatures and protein sources significantly affected the gene expression levels of amino acid transport including solute carrier family 1 member 3 (SLC1A3), solute carrier family 7 member 1 (SLC7A1), solute carrier family 7 member 5 (SLC7A5), solute carrier family 15 member 1b (SLC15A1b), solute carrier family 7 member 7 (SLC7A7), target of rapamycin (TOR), 4E binding protein 1 (4E-BP1) and ribosomal protein S6 kinase 1 (S6K1), intestinal inflammatory including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-8 (IL-8), interleukin-10 (IL-10) and tight junction proteins (occludin, claudin1, claudin3, claudin7 and claudin11) (P ≤ 0.001). Collectively, our results indicated that CHP could be a potential protein source in the case of complete replacement of soybean meal in grass carp.

Identification of Single-Nucleotide Polymorphisms in Differentially Expressed Genes Favoring Soybean Meal Tolerance in Higher-Growth Zebrafish (Danio rerio)

Genetic variability within the same fish species could confer soybean meal (SBM) tolerance in some individuals, thus favoring growth. This study investigates the single-nucleotide polymorphisms (SNPs) in differentially expressed genes (DEGs) favoring SBM tolerance in higher-growth zebrafish (Danio rerio). In a previous work, nineteen families of zebrafish were fed a fish meal diet (100FM control diet) or SBM-based diets supplemented with saponin (50SBM + 2SPN-experimental diet), from juvenile to adult stages. Individuals were selected from families with a genotype-by-environment interaction higher (170 ± 18 mg) or lower (76 ± 10 mg) weight gain on 50SBM + 2SPN in relation to 100FM. Intestinal transcriptomic analysis using RNA-seq revealed six hundred and sixty-five differentially expressed genes in higher-growth fish fed 50SBM + 2SPN diet. In this work, using these results, 47 SNPs in DEGs were selected. These SNPs were genotyped by Sequenom in 340 zebrafish that were fed with a 50SBM + 2SPN diet or with 100FM diet. Marker-trait analysis revealed 4 SNPs associated with growth in 3 immunity-related genes (aif1l, arid3c, and cst14b.2) in response to the 50SBM + 2SPN diet (p-value < 0.05). Two SNPs belonging to aif1l y arid3c produce a positive (+19 mg) and negative (-26 mg) effect on fish growth, respectively. These SNPs can be used as markers to improve the early selection of tolerant fish to SBM diet or other plant-based diets. These genes can be used as biomarkers to identify SNPs in commercial fish, thus contributing to the aquaculture sustainability.

Recirculating frass from food waste bioconversion using black soldier fly larvae: Impacts on process efficiency and product quality

Biowaste generation is increasing worldwide and inadequate disposal has strong negative impacts on food systems and ecosystems. Biodigestion of biowaste using black soldier fly (Hermetia illucens) larvae (BSFL) generates valuable by-products such as animal feed (larval biomass) and organic fertiliser (frass). However, the latter is typically unstable immediately after waste conversion and is thus unsafe for use as a fertilizer in terms of maturity. This study evaluated recirculation of frass within bioconversion of post-consumer food waste (FW) as a dietary component for BSFL to improve the quality of the subsequent frass obtained. Frass was introduced at increasing inclusion levels replacing food waste (2.5-100% on wet-weight basis) as part of the larvae's feeding substrate. Bioconversion efficiency and material reduction were significantly reduced by frass inclusion, while larval yield per experimental unit remained unchanged. When considering only the waste component in the larval diet, larval yield (dry-weight basis) ranged between 207 (0% frass inclusion) and 403 (40% frass inclusion) kg tonne FW-1, thus increasing by up to 94% at higher frass inclusion. With increasing dietary inclusion rate of frass from 0% to 100%, crude protein content of larval biomass increased by 41%, while fat content was reduced by 32%. The recirculated frass (obtained after including frass in the larval diet) had elevated concentrations of P, K, S, Na and B and around 6% lower organic matter content, demonstrating a higher degree of decomposition. Frass inclusion in the larval diet generated recirculated frass that were more stable and mature, as indicated by self-heating capacity, CO2 and NH3 volatilisation, seed germination bioassays and other parameters. It was concluded that frass recirculation improves waste bioconversion efficiency in relation to food waste unit, as well as larval biomass and frass quality, ensuring safer use as a fertilizer.

Investigating the nutritional viability of marine-derived protein for sustainable future development

Marine-derived proteins are emerging as a pivotal resource with diverse applications in food, pharmaceuticals, and biotechnological industries. The marine environment offers many protein sources, including fish, shellfish, algae, and microbes, which garnered attention due to their nutritional composition. Evaluating their protein and amino acid profiles is essential in assessing their viability as substitutes for conventional protein sources. Continuously exploiting marine ecosystems for protein extraction has led to significant environmental impacts. The optimization of aquacultural practices and implementation of innovative practices are imperative for the sustainable production of marine-based protein. This review will discuss the different sources of marine proteins, their nutritional profile, and their associated environmental impact. It also reviews the relationship between aquaculture advancements and regulatory frameworks toward attaining sustainable practices, alongside exploring the challenges and potentials in utilizing marine sources for protein production.

Protein-sparing effects of lipids in the diet of golden pompano (Trachinotus ovatus): evaluation of growth, feed utilization, and lipid metabolism

To investigate the influences of dietary protein and lipid levels on the growth, feed utilization, morphometric parameters, body composition, serum biochemical parameters, and lipid metabolism of golden pompano (Trachinotus ovatus), nine test diets containing three protein levels (35%, 40%, and 45%) and three lipid levels (8%, 13%, and 18%) were designed in the present study. Each diet (named D1-D9) was randomly assigned to feed triplicate groups of golden pompano juvenile (initial weight ~ 70 g) for 50 days. The results showed that the dietary lipid levels positively correlated with weight gain, specific growth rate, and protein efficiency ratio (PER), suggesting that the high lipid diets (18%) can be efficiently utilized in this fish species. The dietary protein levels have no significant influences on the growth and feed utilization except for the PER. Increasing dietary protein levels resulted in a decrease in hepatosomatic index (HSI), viscerosomatic index (VSI), and intestinal somatic index (ISI), while the dietary lipid level did not have a significant impact on morphological indices except for ISI. The dietary protein and lipid levels had no significant influences on the contents of crude lipid, crude ash, and moisture of whole body, while the crude protein contents was significantly affected by the dietary protein levels. Serum biochemical indexes, including cholesterol (CHO), triglycerides (TG), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL), as well as HDL/LDL ratio were significantly affected by the dietary lipid levels, but not by the dietary protein levels. The expression levels of genes and their associated proteins involved in hepatic lipogenesis (Srebp-1c and Fas) and fatty acids β-oxidation (Pparα and Cpt-1) were up-regulated with increasing dietary lipid levels, while the former was up-regulated, and the latter was down-regulated with increasing dietary protein levels. Considering the present results in terms of growth performance, feed utilization, morphometric parameters, and lipid metabolism, the recommended dietary protein and lipid levels for golden pompano are 40% and 18%, respectively. The findings suggested that this species exhibits a significant protein-sparing effect on lipid utilization.

Efficiently Substituting Dietary Fish Meal with Terrestrial Compound Protein Enhances Growth, Health, and Protein Synthesis in Largemouth Bass

Inappropriate substitution of dietary fishmeal (FM) can adversely affect the growth, health, and metabolism of carnivorous fish species. To effectively reduce the amount of dietary FM in carnivorous largemouth bass (Micropterus salmoides), a terrestrial compound protein (Cpro) with chicken meal, bone meal, and black soldier fly protein was used to formulate four isoproteic (52%) and isolipidic (12%) diets, namely T1 (36% FM), T2 (30% FM), T3 (24% FM), and T4 (18% FM), for feeding juveniles (initial weight: ~12 g) for 81 days. Results indicated that the growth performance, feed efficiency, and morphological indicators, as well as muscle texture and edible quality of fish, did not differ significantly among the four groups. However, the muscle protein contents and ATP/AMP ratio of fish in the T4 group were significantly increased in comparison with those of fish in the T1 group, while the opposite was true for muscle glycogen. Compared with the T1 group, high serum total amino acid and MDA contents, as well as low AST activities, were observed in the T3 and T4 groups, and relatively high intestinal trypsin and lipase activities were found in the T2-T4 groups. The transcripts of intestinal proinflammatory cytokines (il-1β, il-6, and tnf-α) were downregulated in the T2-T4 groups compared with T1 group, while the expression of anti-inflammatory cytokines (il-10) and tight junction (zo-1 and occludin) showed the reverse trend. The mRNA expression of positive regulators related to protein synthesis (sirt1, pgc1-α, pi3k, and akt) were significantly upregulated in the muscle of fish fed diets T3 and T4, while their negative regulators (4e-bp1) mRNA levels were downregulated. The results indicate that the dietary FM of largemouth bass could be effectively reduced to at least 18% by the Cpro, which is beneficial to health, digestion, and protein synthesis for maintaining accelerated growth.

Efficiency of protein combinations in diets for Rhamdia quelen: growth, digestive and metabolic biochemistry and nutrient deposition

This study was conducted to determine the best combination of protein sources in diets for jundiá, based on growth, metabolism, and nutrient deposition. Five protein combinations were tested: casein + fish meal (control), casein + gelatin, casein + albumin, casein + albumin + fish meal, and albumin + fish meal, in diets containing 370 g Kg-1 of crude protein and 13.4 MJ Kg-1 of digestible energy. The fish (9.38 ± 0.12 g) were allocated in a water recirculation system at a density of 3.35 g L-1 per experimental unit and fed until apparent satiety for 40 days with the diets. The fish fed with the control diet had the highest final weight, specific growth rate, protein and feed efficiency ratio, protein retention, and best apparent feed conversion. On the other hand, fish that received casein + albumin and albumin + fish meal diets showed worse results in growth and body protein retention, low trypsin and chymotrypsin activity, and high intestinal amylase activity. Therefore, the combination referred to as control (casein + fish meal) conclusively provides the best rhythm for nutrient digestion and metabolism processes, enabling fish to reach greater growth and retention of body protein with low whole-fish fat content.

Multi-Omics Reveals the Effects of Spirulina platensis Powder Replacement of Fish Meal on Intestinal Metabolism and Stress in Zig-Zag Eel (Mastacembelus armatus)

The booming aquaculture industry has created a strong demand for fishmeal and increased environmental pressures. Spirulina, as a potential alternative to fishmeal, has been shown to have growth-promoting and animal health-enhancing properties. In this study, 600 large spiny loaches, divided into five experimental groups, F0, F1, F2, F3, and F4, were reared for 10 weeks using Spirulina platensis powder (SPP) as a substitute for 0%, 5%, 10%, 15%, and 20% of fishmeal, respectively. The results of intestinal physiological indexes showed that superoxide dismutase was lower than F0 in all treatment groups, and the activity of F3 was significantly lower than F0 (p < 0.05). The activity of malondialdehyde was significantly higher than that of F0 in all groups except F3 (p < 0.05). The addition of SPP also led to a decrease in the activity of acid phosphatase in the intestine, which was significantly lower in all treatment groups compared to the F0 group (p < 0.05). The results of serum physiology showed that the activity of superoxide dismutase in serum gradually increased with the increase in the percentage of SPP addition, and the F3 group produced a significant difference from the F0 group (p < 0.05). The transcriptomics results showed that DEGs in the low percentage substitution group (<15%) were mostly enriched in metabolism-related pathways, such as bile secretion; DEGs in the high percentage substitution group (>15%) were mostly enriched in inflammation-related pathways, such as complement p and coagulation cascades. Metabolomics confirmed that nicotinate and nicotinamide metabolism and glycerophospholipid metabolism were the two pathways that were significantly enriched in the treatment groups of fishmeal replacement by SPP. The present study demonstrated that a low percentage (<15%) of fishmeal replacement by SPP in feed mobilized MA digestive metabolism, whereas a high percentage (>15%) of replacement induced intestinal stress. Considering the health and farm efficiency aspects, the proportion of SPP in feed formulation for MA should be less than 15%.

Modulation of metabolic and immunoregulatory pathways in the gut transcriptome of Atlantic salmon (Salmo salar L.) after early nutritional programming during first feeding with plant-based diet

Introduction

Plant-based nutritional programming is the concept of exposing fish at very early life stages to a plant-based diet for a short duration to improve physiological responses when exposed to a similar plant-rich diet at a later developmental stage. The mechanisms of action underlying nutritional programming have not been fully deciphered, and the responses may be controlled at multiple levels.

Methods

This 22-week study examines gut transcriptional changes after nutritional programming. Triplicate groups of Atlantic salmon were fed with a plant (V) vs. a marine-rich (M, control) diet for 2 weeks (stimulus phase) at the first exogenous feeding. Both stimulus fish groups (M and V fish) were then fed the M diet for 12 weeks (intermediate phase) and lastly fed the V diet (challenge phase) for 6 weeks, generating two dietary regimes (MMV and VMV) across phases. This study used a whole-transcriptome approach to analyse the effects of the V diet at the end of stimulus (short-term effects) and 22 weeks post-first feeding (long-term effects). After the stimulus, due to its developmental stage, the whole intestine was used, whereas, after the challenge, pyloric caeca and middle and distal intestines were examined.

Results and discussion

At the stimulus end, genes with increased expression in V fish enriched pathways including regulatory epigenetic responses and lipid metabolism, and genes involved in innate immune response were downregulated. In the middle intestine at the end of the challenge, expression levels of genes of lipid, carbohydrate, and energy metabolism were increased in V fish, while M fish revealed increased expression of genes associated with autoimmune and acute adaptive immune response. The distal intestine of V fish showed increased expression of genes associated with immune response and potential immune tolerance. Conversely, the distal intestine of M fish at challenge revealed upregulation of lipid and carbohydrate metabolic pathways, tissue degeneration, and apoptotic responses. The present study demonstrated nutritional programming-associated changes in the intestinal transcriptome, with altered expression of genes involved in both immune responses and different metabolic processes. While there were limited changes in growth between the groups, the results show that there were transcriptional differences, suggesting a programming response, although the mechanism of this response still requires to be fully elucidated.

Understanding the links between micro/nanoplastics-induced gut microbes dysbiosis and potential diseases in fish: A review

At present, the quantity of micro/nano plastics in the environment is steadily rising, and their pollution has emerged as a global environmental issue. The tendency of their bioaccumulation in aquatic organisms (especially fish) has intensified people's attention to their persistent ecotoxicology. This review critically studies the accumulation of fish in the intestines of fish through active or passive intake of micro/nano plastics, resulting in their accumulation in intestinal organs and subsequent disturbance of intestinal microflora. The key lies in the complex toxic effect on the host after the disturbance of fish intestinal microflora. In addition, this review pointed out the characteristics of micro/nano plastics and the effects of their combined toxicity with adsorbed pollutants on fish intestinal microorganisms, in order to fully understand the characteristics of micro/nano plastics and emphasize the complex interaction between MNPs and other pollutants. We have an in-depth understanding of MNPs-induced intestinal flora disorders and intestinal dysfunction, affecting the host's systemic system, including immune system, nervous system, and reproductive system. The review also underscores the imperative for future research to investigate the toxic effects of prolonged exposure to MNPs, which are crucial for evaluating the ecological risks posed by MNPs and devising strategies to safeguard aquatic organisms.

Effects of essential amino acids supplementation in a low-protein diet on growth performance, intestinal health and microbiota of juvenile blotched snakehead (Channa maculata)

Developing a low-protein feed is important for the sustainable advancement of aquaculture. The aim of this study was to investigate the effects of essential amino acid (EAA) supplementation in a low-protein diet on the growth, intestinal health, and microbiota of the juvenile blotched snakehead, Channa maculata in an 8-week trial conducted in a recirculating aquaculture system. Three isoenergetic diets were formulated to include a control group (48.66 % crude protein (CP), HP), a low protein group (42.54 % CP, LP), and a low protein supplementation EAA group (44.44 % CP, LP-AA). The results showed that significantly lower weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), and feed efficiency ratio (FER) were observed in fish that were fed LP than in the HP and LP-AA groups (P < 0.05). The HP and LP-AA groups exhibited a significant increase in intestinal villus length, villus width, and muscular thickness compared to the LP group (P < 0.05). Additionally, the HP and LP-AA groups demonstrated significantly higher levels of intestinal total antioxidant capacity (T-AOC), catalase (CAT), and superoxide dismutase (SOD) and lower levels of malondialdehyde (MDA) compared to the LP group (P < 0.05). The apoptosis rate of intestinal cells in the LP group was significantly higher than those in the LP and HP groups (P < 0.05). The mRNA expression levels of superoxide dismutase (sod), nuclear factor kappa B p65 subunit (nfκb-p65), heat shock protein 70 (hsp70), and inhibitor of NF-κBα (iκba) in the intestine were significantly higher in the LP group than those in the HP and LP-AA groups (P < 0.05). The 16s RNA analysis indicated that EAA supplementation significantly increased the growth of Desulfovibrio and altered the intestinal microflora. The relative abundances of Firmicutes and Cyanobacteria were positively correlated with antioxidant parameters (CAT and T-AOC), whereas Desulfobacterota was negatively correlated with sod and T-AOC. The genera Bacillus, Bacteroides, and Rothia were associated with the favorable maintenance of gut health. In conclusion, dietary supplementation with EAAs to achieve a balanced amino acid profile could potentially reduce the dietary protein levels from 48.66 % to 44.44 % without adversely affecting the growth and intestinal health of juvenile blotched snakeheads.

Mucosal barrier status in Atlantic salmon fed rapeseed oil and Schizochytrium oil partly or fully replacing fish oil through winter depression

The study was designed to investigate the effects of replacing fish oil by algal oil and rapeseed oil on histomorphology indices of the intestine, skin and gill, mucosal barrier status and immune-related genes of mucin and antimicrobial peptide (AMP) genes in Atlantic salmon (Salmo salar). For these purposes, Atlantic salmon smolts were fed three different diets. The first was a control diet containing fish oil but no Schizochytrium oil. In the second diet, almost 50 % of the fish oil was replaced with algal oil, and in the third diet, fish oil was replaced entirely with algal oil. The algal oil contained mostly docosahexaenoic acid (DHA) and some eicosapentaenoic acid (EPA). The study lasted for 49 days in freshwater (FW), after which some fish from each diet group were transferred to seawater (SW) for a 48-h challenge test at 33 ppt to test their ability to tolerate high salinity. Samples of skin, gills, and mid intestine [both distal (DI) and anterior (AI) portions of the mid intestine] were collected after the feeding trial in FW and after the SW-challenge test to assess the effects of the diets on the structure and immune functions of the mucosal surfaces. The results showed that the 50 % VMO (Veramaris® algal oil) dietary group had improved intestinal, skin, and gill structures. Principal component analysis (PCA) of the histomorphological parameters demonstrated a significant effect of the algal oil on the intestine, skin, and gills. In particular, the mucosal barrier function of the intestine, skin, and gills was enhanced in the VMO 50 % dietary group after the SW challenge, as evidenced by increased mucous cell density. Immunolabelling of heat shock protein 70 (HSP70) in the intestine (both DI and AI) revealed downregulation of the protein expression in the 50 % VMO group and a corresponding upregulation in the 100 % VMO group compared to 0 % VMO. The reactivity of HSP70 in the epithelial cells was higher after the SW challenge compared to the FW phase. Immune-related genes related to mucosal defense, such as mucin genes [muc2, muc5ac1 (DI), muc5ac1 (AI), muc5ac2, muc5b (skin), and muc5ac1 (gills)], and antimicrobial peptide genes [def3 (DI), def3 (AI), and cath1 (skin)] were significantly upregulated in the 50 % VMO group. PCA of gene expression demonstrated the positive influences on gene regulation in the 50 % VMO dietary group. In conclusion, this study demonstrated the positive effect of substituting 50 % of fish oil with algal oil in the diets of Atlantic salmon. The findings of histomorphometry, mucosal mapping, immunohistochemistry, and immune-related genes connected to mucosal responses all support this conclusion.

Growth, Hepatic Enzymatic Activity, and Quality of European Seabass Fed on Hermetia illucens and Poultry By-Product Meal in a Commercial Farm

Protein meals from insects in combination with poultry by-product meal appear to be promising ingredients for replacing conventional proteins in the diets of carnivorous fish. The present study explored the effects on growth performance, hepatic enzymatic activity, and fillet physical and nutritional characteristics during a 66-day feeding trial performed on European seabass. A total of 3000 fish were distributed into three tanks, where the control group was fed with a commercial diet (CG) and a second group was fed in duplicate with the experimental diet (SSH) containing 10% Hermetia illucens larva meal, 30% poultry by-product meal, and <5.5 g/100 g of feed of marine origin proteins. All fish showed good growth performance. Glucose-6-phosphate dehydrogenase, aspartate aminotransferase, and 3-hydroxyacyl-CoA dehydrogenase activities were higher in the SSH group than in the CG group. The fillet fatty acid profile was largely unaffected by diet, except for a few fatty acids. Fish fed the SSH diet had a lower C22:1n-11 content than CG, thus suggesting an increased β-oxidation. The oxidative status of muscle lipids was not affected by the diet. In conclusion, the present study showed that European seabass can be successfully fed the SSH diet for two months in a commercial setting.

An In-Depth Insight into the Profile, Mechanisms, Functions, and Transfer of Essential Amino Acids from Mulberry Leaves to Silkworm Bombyx mori L. Pupae and Fish

The silkworm Bombyx mori, the second most varied group of insects, is a fascinating insect that belongs to the Lepidoptera species. We aimed to deepen our knowledge about the composition and significance of amino acids (AA) from the sericulture chain to fish. AAs are the most prevalent molecules throughout the growth process of silkworms. We described AAs classification, occurrence, metabolism, and functions. Online datasets revealed that the essential AAs (EAA) level in fish meal and silkworm pupae (SWP) is comparable. SWP have a high content of methionine and lysine, which are the principal limiting AAs in fish diets, indicating that SWP have nutritional potential to be added to fish diets. Additionally, an overview of the data analyzed displays that SWP have a higher protein efficiency ratio than fish meal, the classical protein-rich source (>1.19 times), and compared to soybean meal, the second-most preferred source of protein in aquaculture (>2.08 times), indicating that SWP can be considered effective for animal feeding. In this study, we provide an overview of the current knowledge concerning AAs, paying special emphasis to EAAs and explaining, to some extent, certain mechanisms and functions of these compounds, from mulberry leaves to larvae-pupae and fish diets.

Fish Meal Substitution Effects with the Combined Animal Proteins in the Feeds of Olive Flounder (Paralichthys olivaceus) on Growth Performance, Feed Availability, and Disease Resistance against Streptococcus iniae

This study aims to reveal the substitution impact of fish meal (FM) with the combined meat meal and chicken by-product meal (CMC) in the olive flounder (P. olivaceus) feeds on growth and feed availability. Seven experimental feeds were formulated. The control (CMC0) diet included 65% FM. In the CMC0 diet, the various (10%, 20%, 40%, 60%, 80%, and 100%) levels of FM were replaced with CMC, named as the CMC10, CMC20, CMC40, CMC60, CMC80, and CMC100 diets, respectively. The total number of 525 juvenile fish (9.2 ± 0.01 g; mean ± SD) was placed into 21 50-L flow-through tanks (25 juveniles/tank) with three replicates. Fish were hand-fed to apparent satiation for 8 weeks. After the 8-week feeding experiment, olive flounder fed the CMC10 (40.0 ± 0.60 g/fish, 2.99 ± 0.021%/day, and 39.57 ± 0.542 g/fish; mean ± SD), CMC20 (47.3 ± 2.58 g/fish, 3.24 ± 0.082%/day, and 45.16 ± 0.760 g/fish), and CMC40 (40.2 ± 1.17 g/fish, 3.00 ± 0.040%/day, and 39.43 ± 0.930 g/fish) diets attained superior (p < 0.0001 for all) weight gain, specific growth rate (SGR), and feed consumption compared to olive flounder fed the CMC0 (35.1 ± 0.96 g/fish, 2.81 ± 0.039%/day, and 33.75 ± 0.544 g/fish), CMC60 (31.7 ± 1.62 g/fish, 2.66 ± 0.068%/day, and 31.60 ± 1.080 g/fish), CMC80 (24.7 ± 0.63 g/fish, 2.33 ± 0.033%/day, and 25.27 ± 0.689 g/fish), and CMC100 (17.8 ± 0.32 g/fish, 1.92 ± 0.021%/day, and 18.99 ± 0.592 g/fish, respectively) diets. Weight gain, SGR, and feed consumption of olive flounder fed the CMC60 diet were comparable to olive flounder fed the CMC0 diet. Feed efficiency and protein efficiency ratio of olive flounder fed the CMC60 diet (1.02 ± 0.007 and 1.79 ± 0.034) were comparable to fish fed the CMC0 diet (1.04 ± 0.012 and 1.85 ± 0.021, respectively). None of the plasma and serum measurements, proximate composition, amino acid profiles, or survival of olive flounder after S. iniae infection were influenced by dietary treatments. In conclusion, CMC can substitute FM up to 60% (39% FM protein in the diet) without deteriorating growth performance, feed availability, or the survival of fish after S. iniae infection.

Recycling of animal protein wastes in the formulation of feed for Labeo rohita and Mystus vittatus-a comparative evaluation

Lactic acid bacteria (LAB) are key players in the fermentation of organic wastes and their recycling as feedstuff for fish. Whey, a common dairy byproduct in India, is a cheap source of LAB and can be used to ferment animal byproducts. An experimental study was designed to explore whether the whey fermented animal protein blend (WFAPB) could be used as a fishmeal replacer in the formulation of feed for both stomach-less carp fish Labeo rohita and stomach-bearing catfish Mystus vittatus. Experiments were performed with five isoproteinous, isolipidous, and isoenergetic feeds with WFAPB replacing fishmeal (FM) by 0% (T1), 25% (T2), 50% (T3), 75% (T4), and 100% (T5). Fifteen days of laboratory experiments with these experimental feeds revealed that more than 50% FM replacement level could result in excess postprandial absorption (6 h) of some essential and non-essential amino acids in the plasma of both fish. The postprandial absorption was more in M. vittatus than L. rohita. Ninety-day experiments were conducted in outdoor cement vats to measure growths and deposition of amino acids (AA) in muscle. Regression analysis was performed to find the optimal FM replacement based on four growth parameters and fifteen AA deposition in muscle. A two-phase fuzzy methodology was used to obtain Pareto-optimal replacement levels for each fish. The results demonstrated that FM replacement levels were 7.63% and 36.79% respectively for L. rohita and M. vittatus when only four growth parameters were considered. However, based on the FM replacement level that maximized deposition of 15 amino acids and growth parameters, it was found that 12.23% and 40.02% replacement of FM by the WFAPB was ideal respectively for L. rohita and M. vittatus. The results revealed that only a fraction of both essential and non-essential amino acids absorbed in plasma could be converted into protein and deposited as bound amino acids in the muscle. It is concluded that fermentation by whey is an inexpensive, easily available, and environmentally sustainable technique to recycle animal protein in the formulation of feed for fish, and the stomach-bearing carnivorous fish are more efficient in utilizing fermented animal protein blend than the stomach-less carps.

The application of protease in aquaculture: Prospects for enhancing the aquafeed industry

Low-fishmeal and protein-saving diets are two prominent nutritional strategies utilized to address challenges related to the scarcity and sustainability of protein sources in aquaculture. However, these diets have been associated with adverse effects on the growth performance, feed utilization, and disease resistance of aquatic animals. To mitigate these challenges, exogenous protease has been applied to enhance the quality of diets with lower protein contents or fishmeal alternatives, thereby improving the bioavailability of nutritional ingredients. Additionally, protease preparations were also used to enzymatically hydrolyze fishmeal alternatives, thus enhancing their nutritional utilization. The present review aims to consolidate recent research progress on the use of protease in aquaculture and conclude the benefits and limitations of its application, thereby providing a comprehensive understanding of the subject and identifying opportunities for future research.

Microalgae as fishmeal alternatives in aquaculture: current status, existing problems, and possible solutions

Fishmeal is an indispensable ingredient for most aquatic animals. However, the finite supply and escalating price of fishmeal seriously limit its use in aquaculture. Thus the development of new, sustainable protein ingredients has been a research focus. Microalgae are potential fishmeal alternatives owing to their high protein content and balanced amino acid profile. Studies suggest that suitable replacement of fishmeal with microalgae is beneficial for fish growth performance, but excessive replacement would induce poor growth and feed utilization. Therefore, this paper aims to review research on the maximum substitutional level of fishmeal by microalgae and propose the main issues and possible solutions for fishmeal replacement by microalgae. The maximum replacement level is affected by microalgal species, fish feeding habits, quality of fishmeal and microalgal meals, and supplemental levels of fishmeal in the control group. Microalgae could generally replace 100%, 95%, 95%, 64.1%, 25.6%, and 18.6% fishmeal protein in diets of carp, shrimp, catfish, tilapia, marine fish, and salmon and trout, respectively. The main issues with fishmeal replacement using microalgae include low production and high production cost, poor digestibility, and anti-nutritional factors. Possible solutions to these problems are recommended in this paper. Overall, microalgae are promising fishmeal alternatives in aquaculture.

Dietary Replacement Effect of Fish Meal by Tuna By-Product Meal on Growth and Feed Availability of Red Sea Bream (Pagrus major)

The effect of substituting fish meal (FM) by tuna by-product meal (TBM) on growth and feed availability of red sea bream (Pagrus major) was investigated. Six experimental diets were crested to be isonitrogenous (51.5%) and isolipidic (14.5%). The control (Con) diet contained 55% FM. FM substitution in the Con diet was made in increments of 20 percentage points (20, 40, 60, 80, and 100%), named as the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. Juvenile red sea bream were stocked into 18, 300 L flow-through tanks (50 fish/tank). Red sea bream were hand-fed with each diet until satiation for 8 weeks. No statistical differences in weight gain, specific growth rate (SGR), and feed consumption were found among red sea bream fed the Con, TBM20, and TBM40 diets. Furthermore, feed utilization of fish fed the TBM20, TBM40, TBM60, and TBM80 diets was comparable to red sea bream fed the Con diet. The biological indices, biochemical composition, and hematological parameters of fish were not statistically altered by dietary FM replacement with TBM. The greatest economic profit index was achieved in the TBM40 diet. In conclusion, the replacement of 40% FM with TBM in red sea bream diet appears to be the most recommendable approach without producing retarded growth and feed availability, but maximizing EPI to farmers.

Insect-based fish feed in decoupled aquaponic systems: Effect on lettuce production and resource use

The utilisation of insect meal-based fish feed as a substitute for conventional fish meal-based fish feed is considered as a promising innovative alternative to boost circularity in aquaculture and aquaponics. Basic research on its use in aquaponics is limited. So far, no reports on the effects of fish waste water, derived from a recirculating aquaculture system using Black Soldier Fly (BSF) meal-based diets, were available on the growth performance of lettuce. Therefore, this study aimed to compare the effect of reusing fish waste water from tilapia culture (as a base for the nutrient solution) fed with a fish meal-based diet (FM) and a BSF meal-based diet on resource use and lettuce growth in decoupled aquaponic systems. A conventional hydroponics nutrient solution (HP) served as control, and inorganic fertilisers were added to all nutrient solutions to reach comparable target concentrations. The experiment was conducted in a controlled climate chamber in nine separate hydroponics units, three per treatment. Lettuce fresh and dry weight, number of leaves, relative leaf chlorophyll concentration, water consumption, and the usage of inorganic fertilisers were measured. Micro- and macronutrients in the nutrient solutions were monitored in time series. Similar lettuce yield was seen in all treatments, with no significant effects on fresh and dry weight, the number of leaves, and relative chlorophyll values. Water use per plant was also similar between treatments, while the amount of total inorganic fertiliser required was 32% lower in FM and BSF compared to HP. Higher sodium concentrations were found in the FM nutrient solutions compared to BSF and HP. The results confirm that BSF-based diet is a promising alternative to FM-based diet in aquaponics with no negative effects on lettuce growth. Additionally, BSF-based diet might be beneficial in intensive, professional aquaponics applications due to the lower sodium concentration in the nutrient solution.

Effects of Dietary Plant Protein Replacement with Insect and Poultry By-Product Meals on the Liver Health and Serum Metabolites of Sea Bream (Sparus aurata) and Sea Bass (Dicentrarchus labrax)

The liver health of Gilthead sea bream and European sea bass, fed with fish meal-free diets, including various proportions of plant proteins, as well as insect and poultry by-product meals, was investigated through biochemical and histological analyses using a new liver index (LI) formula. Four isoproteic (45% Dry Matter, DM) and isolipidic (20% DM) diets were compared, including a plant-based control diet (CV) and three other test diets, in which 40% of a plant protein-rich ingredient mixture was replaced with meals from Hermetia illucens (H40) or poultry by-product (P40) alone, or in combination (H10P30). The trials lasted 12 and 18 weeks for sea bream and sea bass, respectively. The results obtained thus far highlighted species-specific differences in the physiological response to dietary changes. In sea bream, the biochemical and histological responses suggest favorable physiological and liver health statuses, with higher serum cholesterol (CHO) and triglyceride (TAG) levels, as well as moderate hepatocyte lipid accumulation, with the H10P30 diet compared to the CV (p < 0.05). In sea bass, all diets resulted in elevated serum TAG levels and lipid accumulation in the liver, particularly in fish fed the P40 one (p < 0.05), which resulted in the highest LI, coupled with a higher frequency of severe lipid accumulation, hypertrophy, cord loss, peripheral nuclei displacement, and pyknosis. In conclusion, sea bream adapted well to the test diets, whereas sea bass exhibited altered hepatic lipid metabolism leading to incipient liver steatosis, likely due to the high lipid contents of the diets, including the insect and poultry meals. The LI formula developed in this study proved to be a reliable tool for assessing the effects of dietary changes on the liver health of sea bream and sea bass, consistent with biochemical and histological findings.

Rapid adaptation of the rainbow trout intestinal microbiota to the use of a high-starch 100% plant-based diet

Short-term adaptation of the microbiota could promote nutrient degradation and the host health. While numerous studies are currently undertaking feeding trials using sustainable diets for the aquaculture industry, the extent to which the microbiota adapts to these novel diets is poorly described. The incorporation of carbohydrates (CHO) within a 100% plant-based diet could offer a novel, cost-effective energy source that is readily available, potentially replacing the protein component in the diets. In this study, we investigated the short-term (3 weeks) effects of a high CHO, 100% plant-based diet on the mucosal and digesta associated microbiota diversity and composition, as well as several metabolic parameters in rainbow trout. We highlighted that the mucosa is dominated by Mycoplasma (44.86%). While the diets did not have significant effects on the main phyla (Proteobacteria, Firmicutes, and Actinobacteria), after 3 weeks, a lower abundance of Bacillus genus, and higher abundances of four lactic-acid bacteria were demonstrated in digesta. In addition, no post-prandial hyperglycemia was observed with high carbohydrate intake. These results provide evidence for the rapid adaptation of the gut microbiota and host metabolism to high CHO in combination with 100% plant ingredients in rainbow trout.

Effects of Fishmeal Substitution with Mealworm Meals (Tenebrio molitor and Alphitobius diaperinus) on the Growth, Physiobiochemical Response, Digesta Microbiome, and Immune Genes Expression of Atlantic Salmon (Salmo salar)

A 12-week growth trial was conducted to assess the effects of mealworm meals, as a substitution for fishmeal, on the growth, physiobiochemical responses, digesta microbiome, and immune-related genes expression of Atlantic salmon (Salmo salar). Twenty Atlantic salmon parr (38.5 ± 0.1 g, initial weight) were stocked into each of 16 tanks in a recirculating aquaculture system. A fishmeal-based diet (100% FM) was used as the control treatment and was compared with three test diets where: (1) fishmeal was partially (50%) replaced with defatted mealworm meal, Tenebrio molitor (50% DMM), (2) fishmeal was fully replaced with defatted mealworm meal (100% DMM), and (3) fishmeal was partially replaced with whole lesser mealworm meal, Alphitobius diaperinus (50% WMM). All substitutions were done on a crude protein basis. Each of the four experimental diets was evaluated in quadruplicate tanks as part of randomized design. The results indicated that Atlantic salmon showed high survival (greater or equal to 98.8%), and no significant difference in final growth, feed efficiency, feces stability and condition indices. Hepatosomatic index was lower in fish fed 100% DMM and 50% WMM when compared to fish fed the control diet (100% FM). Whole-body proximate and amino acid compositions were not statistically different between treatments, while essential fatty acids, including linolenic, eicosapentaenoic acid, and homo-a-linolenic, were lower in fish fed 100% DMM. Plasma parameters (total protein, alanine aminotransferase, alkaline phosphatase, and total iron-binding capacity), hepatic peroxide, and antioxidant enzymes were not significantly affected by dietary substitutions, whereas plasma immunoglobulin M showed significantly higher levels in fish fed 50% DMM and 100% DMM when compared to fish fed the control diet (100% FM). The inclusion of mealworm meals significantly impacted the overall microbiome composition but not the richness and evenness of the salmon digesta microbiomes compared to control. The most common genus in all treatments was Pseudomonas, which has been previously shown to have both commensal and pathogenic members. The relative expressions of growth (IGF-I) and protein synthesis (TIPRL) were not significantly different between the treatments, whereas immunoglobulin genes (IgM, IgD, and IgT) were significantly upregulated in fish fed the DMM diets when compared to fish fed the control diet. Overall, this study suggests that the mealworm meals tested could be suitable alternatives to fishmeal in the diet of Atlantic salmon.

Evaluation of Phytase Impact on In Vitro Protein and Phosphorus Bioaccessibility of Two Lupin Species for Rainbow Trout (Oncorhynchus mykiss)

Legumes are an important source of protein, lipids, and other essential nutrients. As the demand for protein and lipids continues to surge on a global scale, there is a growing interest in incorporating legumes into aquafeeds. This shift is driven not only by the escalating growth of the aquaculture sector in recent years but also by the imperative to diminish the dependency on traditional resources like fishmeal (FM) and fish oil. Amongst legumes, different lupin species had been identified as a potential protein source to partially reduce the inclusion of FM in countries such as Australia, Chile, and the European Union. A comprehensive evaluation of their nutritional profiles, overall characteristics, and potential antinutritional factors is essential for informed utilization and the implementation of nutritional enhancement strategies. In pursuit of this goal, an in vitro gastrointestinal simulation system was devised to replicate the digestive conditions of rainbow trout (Oncorhynchus mykiss). The study focused on determining the bioaccessibility of protein and phosphorus within two sweet lupin varieties (alkaloids < 0.05) with high (Lupinus mutabilis) and low (Lupinus angustifolius) native phytic acid content evaluated as whole (W) or dehulled (D) seeds meals and the effect of a single dose of phytase (2,500 FTU/kg DM). Additionally, regular soybean meal (SBM) served as reference (10 treatments with 3 replicates). A 2,500 FTU/kg DM phytase dose increased the levels of PO4-3 released throughout the intestinal phase by 122.6% for L. mutatabilis W, 116.3% for L. mutatabilis D, 65.2% for L. angustifolius W, 59.0% for L. angustifolius D, and 91.8% for SBM compared to controls without phytase. The bioaccessibility of amino acids in varieties treated with phytase increased with respect to the control without phytase. L. mutabilis was found to be a potentially viable alternative as a good quality protein source for the manufacture of environmentally friendly aquafeeds.

Multi-omics characterization of NIST seafood reference materials and alternative matrix preparations

The National Institute of Standards and Technology (NIST) has prepared four seafood reference materials (RMs) for use in food safety and nutrition studies: wild-caught and aquacultured salmon (RM 8256 and RM 8257) and wild-caught and aquacultured shrimp (RM 8258 and RM 8259). These materials were characterized using genetic, metabolomic (1H-NMR, nuclear magnetic resonance and LC-HRMS/MS, liquid chromatography high-resolution tandem mass spectrometry), lipidomic, and proteomic methods to explore their use as matrix-matched, multi-omic differential materials for method development towards identifying product source and/or as quality control in untargeted omics studies. The results from experimental replicates were reproducible for each reference material and analytical method, with the most abundant features reported. Additionally, differences between the materials could be detected, where wild-caught and aquacultured seafood could be distinguished using untargeted metabolite, lipid, and protein analyses. Further processing of the fresh-frozen RMs by freeze-drying revealed the freeze-dried seafoods could still be reliably discerned. These results demonstrate the usefulness of these reference materials as tools for omics instrument validation and measurement harmonization in seafood-related studies. Furthermore, their use as differential quality control (QC) materials, regardless of preparation method, may also provide a tool for laboratories to demonstrate proficiency at discriminating between products based on source/species.

Effects of plant-based proteins and handling stress on intestinal mucus microbiota in rainbow trout

Via 16S rRNA gene amplicon sequencing, this study explores whether the gut mucus microbiota of rainbow trout is affected by the interaction of a plant-protein-based diet and a daily handling stressor (chasing with a fishing net) across two genetic lines (A, B). Initial body weights of fish from lines A and B were 124.7 g and 147.2 g, respectively. Fish were fed 1.5% of body weight per day for 59 days either of two experimental diets, differing in their fish meal [fishmeal-based diet (F): 35%, plant-based diet (V): 7%] and plant-based protein content (diet F: 47%, diet V: 73%). No diet- or stress-related effect on fish performance was observed at the end of the trial. However, we found significantly increased observed ASVs in the intestinal mucus of fish fed diet F compared to diet V. No significant differences in Shannon diversity could be observed between treatments. The autochthonous microbiota in fish fed with diet V was dominated by representatives of the genera Mycoplasma, Cetobacterium, and Ruminococcaceae, whereas Enterobacteriaceae and Photobacterium were significantly associated with diet F. The mucus bacteria in both genetic lines were significantly separated by diet, but neither by stress nor an interaction, as obtained via PERMANOVA. However, pairwise comparisons revealed that the diet effect was only significant in stressed fish. Therefore, our findings indicate that the mucus-associated microbiota is primarily modulated by the protein source, but this modulation is mediated by the stress status of the fish.

High-fat-diet induced inflammation and apoptosis via activation of Ire1α in liver and hepatocytes of black seabream (Acanthopagrus schlegelii)

The present study aimed to reveal the role of inositol-requiring enzyme 1α (Ire1α) in mediating high-fat-diet (HFD) induced inflammation and apoptosis in fish and elucidate underling mechanisms of action. In experiment 1, black seabream juveniles were fed a control diet (Control, 12 % dietary lipid) or a high fat diet (HFD, 19 % dietary lipid) for eight weeks. In experiment 2, primary hepatocytes were isolated from black seabream juveniles and treated with oleic acid (OA, 200 μmol/L), OA + transfection with non-silencing control siRNA (negative control) (OA + NC), and OA + transfection with ire1α-small interfering RNA (OA + siire1α) for 48 h versus untreated (Control). Results indicated that fish fed HFD increased lipid deposition in the liver and caused hepatic steatosis. HFD group had significantly higher ire1α/Ire1α mRNA and phosphorylated protein expression and endoplasmic reticulum stress (ERS) related genes expression compared to the Control group, indicating that ERS was triggered. Meanwhile, feeding HFD induced inflammation and apoptosis by evaluated nuclear factor kappa B (nf-κb) mRNA and phosphorylated Nf-κb p65 protein expression, and c-Jun N-terminal kinase (jnk) mRNA and protein expression. However, knock down of ire1α (OA + siire1α) in primary hepatocytes alleviated OA-induced increased expression of ire1α/Ire1α mRNA and protein expression, nf-κb/Nf-κb p65 mRNA and phosphorylated protein expression, and jnk/Jnk mRNA and phosphorylated protein expression. These findings revealed the underling mechanism of action of HFD in fish, confirming that HFD increased ESR stress and Ire1α that, in turn, activated Nf-κb and Jnk pathways in hepatocytes and liver mediating HFD-induced inflammation and apoptosis.

New Perspective for Macroalgae-Based Animal Feeding in the Context of Challenging Sustainable Food Production

Food production is facing challenging times due to the pandemic, and climate change. With production expected to double by 2050, there is a need for a new paradigm in sustainable animal feed supply. Seaweeds offer a highly valuable opportunity in this regard. Seaweeds are classified into three categories: brown (Phaeophyceae), red (Rhodophyceae), and green (Chlorophyceae). While they have traditionally been used in aquafeed, their demand in the feed market is growing, parallelly increasing according to the food demand. Additionally, seaweeds are being promoted for their nutritional benefits, which contribute to the health, growth, and performance of animals intended for human consumption. Moreover, seaweeds contain biologically active compounds such as polyunsaturated fatty acids, antioxidants (polyphenols), and pigments (chlorophylls and carotenoids), which possess beneficial properties, including antibacterial, antifungal, antiviral, antioxidant, and anti-inflammatory effects and act as prebiotics. This review offers a new perspective on the valorization of macroalgae biomass due to their nutritional profile and bioactive components, which have the potential to play a crucial role in animal growth and making possible new sources of healthy food ingredients.

Extraction methods and nutritional characterization of protein concentrates obtained from bean, chickpea, and corn discard grains

Protein concentrates obtained from discarded grain flours of white chickpea Sinaloa (Cicer arietinum) (CC), "Azufrazin" bean (Phaseolus vulgaris) (BC), and white corn (Zea mays) (MC), were characterized biochemically through bromatological analyses (protein, lipid, fiber, moisture, ashes, and nitrogen free extract), HPLC techniques (amino acids content), and spectrophotometry (anti-nutrients: phytic acid, trypsin inhibitors, and saponins). The percentage of protein obtained from CC, BC, and MC was 71.23, 81.10, and 55.69%, respectively. Most peptides in the BC and CC flours had a molecular weight of <1.35 kDa, meanwhile, MC peptides were heavier (1.35 to 17 kDa). The amino acids (AA) profile of flours and protein concentrates were similar; however, all the protein concentrates showed an increased AA accumulation (300 to -400%) compared with their flours. The protein concentrates from BC registered the highest AA accumulation (77.4 g of AA/100 g of protein concentrates). Except for the phytic acid in CC and trypsin inhibitor in CC and MC, respectively, the rest of the protein concentrates exhibited higher amounts of the anti-nutrients compared with their flours; however, these levels do not exceed the reported toxicity for some animals, mainly when used in combination with other ingredients for feed formulations. It is concluded that CC and BC protein concentrates showed better nutritional characteristics than MC (level of protein, size of peptides, and AA profile). After biochemical characterization, protein concentrates derived from by-products have nutritional potential for the animal feed industry.

Excessive dietary soluble arabinoxylan impairs the intestinal physical and immunological barriers via activating MAPK/NF-κB signaling pathway in rainbow trout (Oncorhynchus mykiss)

Arabinoxylan (AX) has been deemed as an antinutritional factor, but limited information has addressed the effects of dietary AX on intestinal health of fish. The present study investigated the effects of dietary AX on intestinal mucosal physical and immunological barriers of rainbow trout (Oncorhynchus mykiss). Five isoproteic and isolipidic experimental diets (AXE, AX0, AX2.5, AX5 and AX10) were formulated to contain 0.03% arabinoxylanase as well as 0%, 2.5%, 5% and 10% AX, respectively. Each diet was randomly distributed to triplicate groups of 35 juvenile (average weight 3.14 ± 0.02 g) per tank in a rearing system maintained at 17 ± 1 °C for 9 weeks. Dietary AX supplementation regardless of inclusion levels significantly (P < 0.05) depressed the growth performance and feed utilization. The plasma endothelin-1 and d-lactic acid contents as well as diamino oxidase activity were significantly higher in fish fed diet AX10 compared to fish fed diet AX0. Dietary inclusion of 5-10% AX resulted in decreased intestinal villus height, goblet cell number and desmosome density, increased crypt depth, short and irregular microvilli, widened intercellular space; down-regulated the mRNA levels of occludin in hindgut, claudin3 and ZO-1 in foregut and midgut, but up-regulated the mRNA levels of claudin12 and claudin15 in midgut as well as claudin23 in foregut, midgut and hindgut. Furthermore, dietary 5-10% AX supplementation decreased the midgut and hindgut complement 3, complement 4 and sIgT contents as well as the midgut IgM and hindgut IL-10 contents. Conversely, the hindgut TNF-α and IL-6 contents increased with the rising dietary AX level. RT-qPCR demonstrated that the pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12β, IFN-γ, and TNF-α) and pIgR mRNA levels in midgut and hindgut were up-regulated by dietary AX inclusion of 5-10% AX. Meanwhile, the mRNA levels of p38 MAPK, IκBα, and NF-κB p65 in midgut and hindgut raised gradually with the increasing dietary AX content. The Western blot results showed that the protein expression levels of p38 MAPK and NF-κB generally increased with the rising dietary AX content. Dietary treatment with 0.03% arabinoxylanase did not affect the growth performance and intestinal health of rainbow trout (P > 0.05). In conclusion, excessive dietary AX inclusion (5-10%) increased the intestinal permeability and induced the intestinal inflammatory response via activating MAPK/NF-κB signaling pathway, and ultimately damaged the intestinal barrier function of rainbow trout.

Effect of feed enriched by products formulated from coconut water, palm sap sugar, and mushroom on the chemical composition of feed and carcass, growth performance, body indices, and gut micromorphology of giant gourami, Osphronemus goramy (Lacepède, 1801), juveniles

Background: Giant gourami, Osphronemus goramy is the most important freshwater fish species produced by aquaculture in Indonesia. This study aimed to the effects of various newly formulated products on the amino acid composition of the diet and whole-body carcass, and to analyse the growth coefficient, body indices, and gut micromorphology. Methods: One hundred gram of palm sap sugar was cooked in 1.1 litre of fresh water for fifteen minutes, to create 1 litre of 11% palm sap sugar solution (after some of it had been boiled off). Two litres of coconut water were then mixed with the litre of palm sugar solution. One litre of this product was added in turn to 2 g of Aspergillus niger (CP2), 2 g of Rhizopus oligosporus (CP3), and 2 g of Saccharomyces cerevisiae (CP4), while freshwater was used as a control (labeled CP1). Aquafeed was added to CP1, CP2, CP3, and CP4, to make diets labeled KP1, KP2, KP3, and KP4. The dosage was 150 ml/kg of feed. Juvenile giant gourami (initial weight 50±0.25 g and length 13.2±0.07 cm) were reared in triplicate net frames (2×1×1 m; water volume 1.5 m 3) in a freshwater concrete pond with a stocking density of 30 juveniles/net. Results: The results supported our hypothesis that different product formulations have a significant effect (P < 0.05) on aquafeed nutrition and the whole-body carcass, growth coefficient, feed utilization, body indices, and gut micromorphology of giant gourami juveniles. The thermal growth coefficient strongly correlated with the daily growth coefficient (r 2 = 92%), condition factor (r 2 = 77%), protein efficiency ratio (r 2 = 75%), while a moderate relationship with the feed intake ( r 2 = 69%). Conclusions: Diet KP3 contains higher total amino acids in diets and carcasses and leads to feed efficiency and better growth for giant gourami.

Effect of feed enriched by products formulated from coconut water, palm sap sugar, and mushroom on the chemical composition of feed and carcass, growth performance, body indices, and gut micromorphology of giant gourami, Osphronemus goramy (Lacepède, 1801), juveniles

Background: Giant gourami, Osphronemus goramy is the most important freshwater fish species produced by aquaculture in Indonesia. This study aimed to the effects of various newly formulated products on the amino acid composition of the diet and whole-body carcass, and to analyse the growth coefficient, body indices, and gut micromorphology. Methods: One hundred gram of palm sap sugar was cooked in 1.1 litre of fresh water for fifteen minutes, to create 1 litre of 11% palm sap sugar solution (after some of it had been boiled off). Two litres of coconut water were then mixed with the litre of palm sugar solution. One litre of this product was added in turn to 2 g of Aspergillus niger (CP2), 2 g of Rhizopus oligosporus (CP3), and 2 g of Saccharomyces cerevisiae (CP4), while freshwater was used as a control (labeled CP1). Aquafeed was added to CP1, CP2, CP3, and CP4, to make diets labeled KP1, KP2, KP3, and KP4. The dosage was 150 ml/kg of feed. Juvenile giant gourami (initial weight 50±0.25 g and length 13.2±0.07 cm) were reared in triplicate net frames (2×1×1 m; water volume 1.5 m 3) in a freshwater concrete pond with a stocking density of 30 juveniles/net. Results: The results supported our hypothesis that different product formulations have a significant effect (P < 0.05) on aquafeed nutrition and the whole-body carcass, growth coefficient, feed utilization, body indices, and gut micromorphology of giant gourami juveniles. The thermal growth coefficient strongly correlated with the daily growth coefficient (r 2 = 92%), condition factor (r 2 = 77%), protein efficiency ratio (r 2 = 75%), while a moderate relationship with the feed intake ( r 2 = 69%). Conclusions: Diet KP3 contains higher total amino acids in diets and carcasses and leads to feed efficiency and better growth for giant gourami.

The Effects of Dietary Protein Level on the Growth Performance, Body Composition, Intestinal Digestion and Microbiota of Litopenaeus vannamei Fed Chlorella sorokiniana as the Main Protein Source

This study investigated the effect of dietary protein levels on Litopenaeus vannamei. Five isolipid diets with protein levels of 32%, 36%, 40%, 44% and 48% were prepared using C. sorokiniana as the main protein source. L. vannamei (initial body weight 0.83 ± 0.02 g) were fed these five diets for 8 weeks and referred to as the CHL32, CHL36, CHL40, CHL44 and CHL48 groups, respectively. When the feeding trial was finished, the growth performance, body composition, intestinal digestion and microbiota of L. vannamei were studied. The results showed that the maximum weight gain rate (WGR) of L. vannamei was in the CHL40 group while the lowest feed conversion ratio (FCR) was in the CHL48 group. According to the regression analysis using WGR as the evaluation index, the best growth performance of L. vannamei was obtained when the dietary protein level was 40.81%. The crude protein content of whole shrimp showed an increasing and then decreasing trend with increasing dietary protein levels. Furthermore, the L. vannamei muscle amino acid composition was relatively stable and, to some extent, independent of dietary protein levels. Trypsin, lipase and amylase (AMS) activity increased and then decreased with increasing dietary protein levels and, significantly, peaked in the CHL44 group. Analysis of the alpha diversity of the intestinal microbiota showed that the Chao1 index peaked in the CHL40 group and was significantly lower in the CHL48 group. Additionally, the relative abundance of pathogenic bacteria decreased significantly while the relative abundance of beneficial bacteria increased significantly in the intestine of L. vannamei as the dietary protein levels increased. The functional prediction of the intestinal microbiota revealed that dietary protein levels may influence the growth of L. vannamei by regulating various metabolic activities, and the highest WGR in the CHL40 group may have been related to the significant enrichment of nicotinate and nicotinamide metabolism and biotin metabolism functions. In summary, the optimal protein requirement for L. vannamei was around 40% when C. sorokiniana was used as the primary protein source. Too high or too low dietary protein levels could adversely affect shrimp body composition, intestinal digestion and microbiota.

Development of a time-resolved fluoroimmunoassay for salmonid insulin-like growth factor binding protein-2b

Insulin-like growth factor (IGF)-1 promotes the growth of vertebrates, and its binding proteins (IGFBPs) regulate the activity of circulating IGF-1. Three IGFBPs, IGFBP-2b, -1a, and -1b, were consistently detected in the circulatory system of salmonids. IGFBP-2b is thought to be the main carrier of IGFs and promoter of IGF-1-mediated growth in salmonids. Currently, there are no immunoassays for detecting IGFBP-2b. In this study, we developed a time-resolved fluoroimmunoassay (TR-FIA) for IGFBP-2b detection in salmonid fishes. To establish TR-FIA, we produced two recombinant trout (rt) IGFBP-2bs expressed, one with thioredoxin (Trx) and a histidine (His) tag, and the other with His-tag only. We labeled both recombinant proteins with europium (Eu). Only Eu-Trx.His.rtIGFBP-2b cross-reacted with anti-IGFBP-2b, and the addition of increasing amounts of Trx.His.rtIGFBP-2b replaced the binding, indicating its utility as a tracer and assay standard. The addition of unlabeled salmon IGF-1 did not affect the binding of the standard or sample. Serial dilution curves of sera from rainbow trout, Chinook salmon, and chum salmon were parallel to those of the standard. The assay range (ED80-ED20) of the TR-FIA was 60.4 to 251.3 ng/ml, and its minimum detection limit of this assay was 21 ng/ml. The intra- and inter-assay coefficients of variation were 5.68% and 5.65%, respectively. Circulating IGFBP-2b levels in fed rainbow trout were higher than those in fasted fish and were correlated with individual growth rates. This TR-FIA is useful for further exploring the physiological responses of circulating IGFBP-2b and evaluating the growth status of salmonids.

Momordica charantia saponins administration in low-protein-high-carbohydrate diet improves growth, blood biochemical, intestinal health and microflora composition of juvenile common carp (Cyprinus carpio)

An 8-week feeding trial was conducted to explore the feasibility of Momordica charantia saponins (MCS) administration to facilitate the protein-sparing action of high carbohydrate in diets for juvenile common carp (Cyprinus carpio) with initial mass of 5.41 ± 0.02 g. Based on our previous study, four diets with different the ratio of protein and carbohydrate (P/C ratio) were designed: 32%P/40%C, 30%P/43%C, 28%P/46%C, 28%P/46%C supplemented with 0.16% MCS (28%P/46%C + MCS). Each diet treatment was divided into 3 replicates. Results revealed that 30%P/43%C group increased growth performance and intestinal digestion, decreased intestinal inflammation, and optimized the intestinal microbiota compared to 32%P/40%C group, which presented the stronger protein-sparing action of high carbohydrate. But if the P/C ratio reduced to 28%P/46%C or less, the saving action would be restrained. However, compared to the 30%P/43%C and 28%P/46%C groups, 28%P/46%C + MCS group significantly elevated growth performance and activities of digestive enzymes and antioxidative enzymes, whilst the opposite trend occurred in the contents of glucose, triglyceride, total cholesterol, low density lipoprotein cholesterol, blood urea nitrogen, glutamic oxalacetic transaminase, glutamic-pyruvic transaminase and malondialdehyde. In addition, 28%P/46%C + MCS group markedly upregulated the expressions of GH/IGF axis genes, genes involved in protein synthesis, antioxidant genes and anti-inflammatory cytokine, whilst the opposite trend occurred in the expressions of pro-inflammatory cytokines. Moreover, 28%P/46%C + MCS group obtained the remarkably higher Enterococcus proportion and lower Lactococcus proportion compared to the 30%P/43%C and 28%P/46%C groups, whereas the opposite occurred in 30%P/43%C group, which indicated that there existed differences in the improvement mechanism on intestinal microflora composition between MCS and appropriate P/C ratio. Combined with the above mentioned changes in our research, we concluded that 0.16% MCS administration in a 28%P/46%C diet could facilitate the protein-sparing action of high carbohydrate in diets for common carp, which could decrease the 5% dosage of soybean meal and synchronously reduce the 4% crude protein of diets without affecting the growth and immune ability for common carp.

Chemical and Physical Properties of African Catfish (Clarias gariepinus) Fillet Following Prolonged Feeding with Insect Meal-Based Diets

A 25-week experiment was undertaken to explore the effect of partial replacement of dietary fishmeal (FM) with black soldier fly meal (Hermetia illucens) (BS), mealworm meal (Tenebrio molitor) (MW), and a 1 : 1 mixture of both insect meals (BSMW) on fillet quality in African catfish (Clarias gariepinus). A total of 96 fish with an average initial body weight of 248 ± 28 g were stocked into a recirculating aquaculture system and fed in four different dietary groups (control, BS, MW, and BSMW). No mortality was recorded in any of the groups. At the end of the feeding period, 24 fish (n = 6 for each treatment, weight between 690 and 822 g) were used for analysis. There was no alteration in filleting yield or other slaughter indices within experimental groups, except the hepatosomatic index. Among quality attributes, pH 24 hr postmortem exhibited a significant difference (p < 0.05). In respect of the fatty acid profile, the n-6/n-3 ratio ranged between 1.17 and 1.40 but was not significantly modified by the partial replacement of FM. Similarly, the proximate composition of the fillets was not significantly different between the control and experimental diet groups. The ratio of polyunsaturated fatty acid to saturated fatty acids ranged between 0.67 and 0.79 in the fillets, without significant differences between groups. The atherogenic index was increased in the BS group, as compared to the others; however, the thrombogenicity index of fillets was not significantly affected. Similarly, the conventional quality traits of the fillet, such as cooking, drip, and thawing losses, did not differ within treatments. This study demonstrates that the dietary inclusion of black soldier fly and/or mealworm meals used for African catfish at the tested inclusion level has negligible impact on fillet properties.

Solid-State Fermentation as Green Technology to Improve the Use of Plant Feedstuffs as Ingredients in Diets for European Sea Bass (Dicentrarchus labrax) Juveniles

This study aimed to evaluate the utilization by juvenile European sea bass of a SSFed PF mixture with Aspergillus niger CECT 2088. A 22-day digestibility and a 50-day growth trial were performed testing four diets, including 20 or 40% of an unfermented or SSFed PF mixture (rapeseed, soybean, rice bran, and sunflower seed meals, 25% each). SSF of the PF added cellulase and β-glucosidase activity to the diets. Mycotoxin contamination was not detected in any of the experimental diets except for residual levels of zearalenone and deoxynivalenol (100 and 600 times lower than that established by the European Commission Recommendation-2006/576/EC). In diets including 20% PF, SSF did not affect growth but increased apparent digestibility coefficients of protein and energy, feed efficiency, and protein efficiency ratio. On the contrary, in diets including 40% PF, SSF decreased growth performance, feed intake, feed and protein efficiency, and diet digestibility. SSF decreased the intestinal amylase activity in the 40% SSFed diet, while total alkaline proteases decreased in the 20% and 40% SSFed diets. Hepatic amino acid catabolic enzyme activity was not modulated by SSF, and plasma total protein, cholesterol, and triglyceride levels were similar among dietary treatments. In conclusion, dietary inclusion of moderate levels of the SSFed PF, up to 20%, improves the overall feed utilization efficiency without negatively impacting European sea bass growth performance. The replacement of PF with the SSFed PF mixture may contribute to reducing the environmental footprint of aquaculture production.

The current state of research and potential applications of insects for resource recovery and aquaculture feed

Concerns about fishmeal use and its ecological footprints must be addressed for the aquaculture industry to move on as a sustainable food production sector. Through recent research outcomes, the insect-based meals in fish diets have promise and harnessed promises for commercial applications. In this midst, the efficiency of the selected insects in valorizing biological waste, as well as the nutritional profile of the harvested insects for use in fish diets, will be the driving forces behind such an approach. More extensive research has been published on the suitability of the waste substrate, the nutritional profiling of the meals, the level of substitution, the effects on growth, the immune physiology, and the flesh quality of the animals. Previously, there are only a few reviews available in insect protein applications in aqua feed that focused particularly on the nutritional quality and substitution levels. Considering the dearth of available work, the goal of this review is to provide a more comprehensive account of the resource recovery potential of insects and its derivatives, with a special emphasis on quality as determined by substrate used and processing techniques. Suggestions and policy implications for a sustainable approach to achieving a circular bio-economy of insect farming and its application in aquaculture are discussed for progression and advancement of the existing state of the art.

Calanus finmarchicus hydrolysate improves growth performance in feeding trial with European sea bass juveniles and increases skeletal muscle growth in cell studies

The world will be dependent on the development of novel feed ingredients from renewable sources to ensure sustainable growth of the aquaculture industry. Zooplankton like Calanus finmarchicus are viable new raw material candidates, as they have optimal nutrient profiles for aquatic animals and may be sustainably harvested in large volumes. In this study, the aim was to investigate if a protein hydrolysate of C. finmarchicus was able to influence the growth performance of fish. The effect of dietary inclusion of hydrolysates was tested in a feeding trial with European sea bass (Dicentrarchus labrax) juveniles, benchmarking calanus hydrolysate (CH) against commercially available hydrolysates. The diet with CH inclusion yielded increased growth, with significantly higher body weight than hydrolysates of sardine and tuna fish at the end of the trial. The observed growth-promoting effects were further examined using an in vitro model with skeletal muscle cells from Atlantic salmon. Through bioactivity experiments with muscle cells grown in media containing CH, low-molecular fractions were found to have the greatest positive effect on proliferation, viability, and expression of muscle-specific genes. Characterization of the most potent fraction revealed an abundance of small peptides, along with amino acids and marine metabolites associated with increased muscle growth.

The Effects of Lipoic Acid on Yolk Nutrient Utilization, Energy Metabolism, and Redox Balance over Time in Artemia sp

Lipoic acid (LA) is a mitochondrial coenzyme that, depending on the concentration and exposure time, can behave as an antioxidant or pro-oxidant agent and has a proven ability to modulate metabolism by promoting lipid and glucose oxidation for energy production. To assess the effects of LA on energy metabolism and redox balance over time, Artemia sp. nauplii was used as an animal model. The administered concentrations of the antioxidant were 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 µM. Therefore, possible differences in protein, triglyceride, glucose, and lactate concentrations in the artemia samples and total ammoniacal nitrogen (TAN) in the culture water were evaluated. We also measured the effects of LA on in vivo activity of the electron transport system (ETS), antioxidant capacity, and production of reactive oxygen species (ROS) at 6, 12, 18, and 24 h post-hatching. There was a decrease in glucose concentration in the LA-treated animals, and a decrease in ammonia production was observed in the 0.5 µM LA treatment. ETS activity was positively regulated by the addition of LA, with the most significant effects at concentrations of 5.0 and 10.0 µM at 12 and 24 h. For ETS activity, treatments with LA presented the highest values at 24 h, a period when ROS production decreased significantly, for the treatment with 10.0 µM. LA showed positive regulation of energy metabolism together with a decrease in ROS and TAN excretion.

Replacement Effect of Fish Meal by Plant Protein Sources in Olive Flounder (Paralichthys olivaceus) Feeds with an Addition of Jack Mackerel Meal on Growth, Feed Availability, and Biochemical Composition

Application of feed stimulants is very helpful to increase the feed intake of fish, especially in the development of low fish meal (FM) diets. FM replacement effect by various plant protein sources (corn gluten meal (CGM), soy protein concentrate (SPC), and corn protein concentrate (CPC)) in diets with an addition of jack mackerel meal (JMM) as feed stimulants on growth, feed availability, and biochemical composition of olive flounder was elucidated. An experimental design of two-way (two replacement levels (25% and 50%) × 3 replacement sources (CGM, SPC, and CPC)) analysis of variance was adopted. Seven diets were formulated. Amount of 60% FM was contained in the control (Con) diet. In the Con diet, 25% and 50% FM were replaced by CGM, SPC, and CPC with an addition of 12% JMM as feed stimulants, referred to as the CGM25, CGM50, SPC25, SPC50, CPC25, and CPC50 diets, respectively. Four hundred and twenty juvenile fish were distributed into 21 flow-through tanks. All diets were assigned to triplicate groups of fish. Fish were hand-fed to satiation twice a day for 56 days. Both dietary replacement levels and sources had statistical effect on weight gain (P < 0.0001 and P < 0.045, respectively), specific growth rate (SGR) (P < 0.0001 and P < 0.033), and feed consumption (P < 0.0001 and P < 0.03) of fish. Dietary increased FM replacement levels lowered weight gain, SGR, and feed consumption of fish. Weight gain, SGR, and feed consumption of fish fed the Con and CGM25 diets were statistically (P < 0.05) greater than those of fish fed the CGM50, SPC50, and CPC50 diets. Both replacement level and source had no statistical effect on feed utilization, biochemical composition except for statistical effect of replacement source on glycine content of fish, and lysozyme and superoxide dismutase (SOD) activities of fish. FM up to 25% could be substituted with CGM, SPC, and CPC in the olive flounder feeds supplemented with 12% JMM as feed stimulants without compromising growth, feed utilization, and lysozyme and SOD activities.

Effect of Dietary Incorporation of Yellow Mealworm as a Partial Fishmeal Replacer on Growth, Metabolism, and Intestinal Histomorphology in Juvenile Meagre (Argyrosomus regius)

Efforts have been made to find alternatives to fish meal (FM), as the sustainability of aquaculture depends on it. Insect meal (IM) is a potential candidate to partially replace FM, being more sustainable and economically viable. In this experimental trial, three diets were tested with different yellow mealworm incorporation: a control diet with no IM, a diet with an inclusion of 10% IM (Ins10), and a diet with an incorporation of 20% IM (Ins20). The diets were tested on 10.5 g meagre for 47 days. The results showed that an IM inclusion higher than 10% affected both growth (2.6 vs. 2.2) and FCR (1.5 vs. 1.9) of meagre juveniles. However, this reduction in growth did not result from lower protein retention or changes in muscle fibre area or density. Little differences were observed in the activity of pancreatic and intestinal enzymes except for aminopeptidase total activity which was higher in the control and Ins10 compared to Ins20 (3847 vs. 3540 mU/mg protein), suggesting no limitations in protein synthesis. Also, the alkaline phosphatase intestinal maturation index was higher in the control group compared to the IM groups (437 vs. 296). On the contrary, several differences were also found in the proteolytic activity in the hepatic and muscle tissues of meagre juveniles fed the Ins10 diet. The inclusion of IM had no impact on intestine histomorphology but changes were detected in the enterocytes of fish from control and Ins10 which showed hypervacuolization and nucleus misplacement compared to the Ins20 treatment. Nevertheless, a higher percentage of Vibrionaceae was recorded for meagre fed on the Ins20 diet. Since no signs of inflammation were observed in the distal intestine, this suggests IM incorporation could have had an important impact on intestinal health due to its antimicrobial properties. This is supported by an increase in the haematocrit in the treatments where IM was added (20 to 25%). In conclusion, incorporations of IM at percentages up to 10% do not seem to have a negative impact on meagre performance at this age but can enhance the fish immune system and protection against intestinal inflammation.

Cell destruction level and metabolites green-extraction of Tetraselmis suecica by low and intermediate frequency ultrasound

Low (20 kHz) and intermediate (100 kHz) frequency ultrasound (US) were studied for their efficiency on cell destruction and metabolites extraction of the microalga T. suecica. This study revealed different levels of cell destruction. Firstly, the prolonged irradiation of US at low frequency allowed the extraction of 90% of total proteins and 70% of carbohydrates by rapidly inducing at high power (100 W or 200 W) a coiling up phenomenon of the cell walls on themselves. A low power (50 W) over short times allows extracting proteins by the perforation of the cells without destroying them, opening the perspective of milking. Furthermore, the use of 100 kHz frequency, showed lower yields of metabolites as well as a low level of cell destruction, resulting in a simple deflation of the cells.

Enhancing Rearing of European Seabass (Dicentrarchus labrax) in Aquaponic Systems: Investigating the Effects of Enriched Black Soldier Fly (Hermetia illucens) Prepupae Meal on Fish Welfare and Quality Traits

Within the modern aquaculture goals, the present study aimed to couple sustainable aquafeed formulation and culturing systems. Two experimental diets characterized by 3 and 20% of fish meal replacement with full-fat spirulina-enriched black soldier fly (Hermetia illucens) prepupae meal (HPM3 and HPM20, respectively) were tested on European seabass (Dicentrarchus labrax) juveniles during a 90-day feeding trial performed in aquaponic systems. The experimental diets ensured 100% survival and proper zootechnical performance. No behavioral alterations were evidenced in fish. Histological and molecular analyses did not reveal structural alterations and signs of inflammation at the intestinal level, highlighting the beneficial role on gut health of bioactive molecules typical of HPM or derived from the enriching procedure of insects' growth substrate with spirulina. Considering the quality traits, the tested experimental diets did not negatively alter the fillet's fatty acid profile and did not compromise the fillet's physical features. In addition, the results highlighted a possible role of spirulina-enriched HPM in preserving the fillet from lipid oxidation. Taken together, these results corroborate the use of sustainable ingredients (spirulina-enriched HPM) in aquaponic systems for euryhaline fish rearing.

Fatty acid composition on diet and carcasses, growth, body indices and profile serum of Asian redtail catfish ( Hemibagrus nemurus) fed a diet containing different levels of EPA and DHA

Background: The Asian redtail catfish Hemibagrus nemurus is a promising commercial aquaculture freshwater big-sized Bagridae catfish across Asian countries such as the Mekong, Malay Peninsula, and Indonesia. This study analysed the effect of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) supplementation in diets on changes in fatty acid compositions in feed and fish meat, lipid quality (atherogenic index and thrombogenic index), growth rate, body indicators, and serum metabolites of Hemibagrus nemurus juveniles . Methods: A total of 180 Asian redtail catfish (initial weight 54.80 ± 2.72 g) were fed four levels (0, 3,150, 6,300, and 9,450 mg of EPA+DHA/kg feed) sourced from fish oil. Diets were fed in triplicate in freshwater tarpaulin ponds, with 15 fish per tarpaulin pond. During the experiment, fish were fed 3% per day of the biomass weight. Results: Categorically, there were significant differences in the composition of fatty acids in the feed and fish meat. The atherogenic index was between 1.76 and 1.84, and the thrombogenic index was between 0.81 and 0.89 in all fish meat. Growth performance was significantly different between diets, while body indices did not make a significant difference between diets. The fish meat EPA and DHA showed positive linear relationships with diet EPA (p <0.001, r ² = 90%) and DHA diet (p<0.001, r ²= 85%). Serum metabolites among treatments D2 and D3 diet-fed feed for 60 days did not significantly differ. Glucose (GLU) levels had moderate relationships with triglycerides (TAG) ( r ²= 65%), and GLU levels strongly correlated with low-density lipoprotein cholesterol (LDL-C) ( r ²= 81%). Conclusions: Based on diets and whole-body carcass compositions, growth performance, and serum metabolites, Asian redtail catfish fed a diet containing 6,300 mg of EPA+DHA/kg feed are best for food safety.

Could Insect Products Provide a Safe and Sustainable Feed Alternative for the Poultry Industry? A Comprehensive Review

The planet is home to more than 2000 species of edible insects, some of which have been consumed as food for many years. Recently, edible insect products have been gradually increasing in several countries, such as Italy and Egypt, as novel feed resources for humans and animals due to their availability, potential economic benefits, and high nutritive value. The insect industry can provide a new solution for livestock nutrition and offer many additional advantages, but there are obstacles to overcome, such as some nutritional organizations that forbid its usage. Nevertheless, previous research indicates that different insect species could be used safely as nutraceuticals in poultry farming to improve broiler growth performance (>3%) and layer egg production (>5%). Among these species, there are various products and extracts that can be used in poultry nutrition in a sustainable manner. This review provides an outline of insect composition, nutrient values, application in poultry feed, safety, and guidelines, and finally, the future perspectives of insects as an alternative feed source in poultry diets.

1H-NMR-Based Metabolic Profiling in Muscle and Liver Tissue of Juvenile Turbot (Scophthalmus maximus) Fed with Plant and Animal Protein Sources

Circular economy driven feed ingredients and emerging protein sources, such as insects and microbial meals, has the potential to partially replace fishmeal in diets of high-trophic fish. Even though growth and feed performance are often unaffected at low inclusion levels, the metabolic effects are unknown. This study examined the metabolic response of juvenile turbot (Scophthalmus maximus) to diets with graded fishmeal replacement with plant, animal, and emerging protein sources (PLANT, PAP, and MIX) in comparison to a commercial-like diet (CTRL). A ¹H-nuclear magnetic resonance (NMR) spectroscopy was used to assess the metabolic profiles of muscle and liver tissue after feeding the fish the experimental diets for 16 weeks. The comparative approach revealed a decrease in metabolites that are associated with energy deficiency in both tissues of fish fed with fishmeal-reduced diets compared to the commercial-like diet (CTRL). Since growth and feeding performance were unaffected, the observed metabolic response suggests that the balanced feed formulations, especially at lower fishmeal replacement levels, have the potential for industry application.