Search Results (81)

Overcoming fishmeal dependence is crucial for the sustainable development of Penaeus vannamei aquaculture, yet the molecular mechanisms underlying the efficient utilization of plant-based diets remain poorly understood. In this study, residual feed intake (RFI) was used as an indicator to investigate these mechanisms. Transcriptome sequencing of the intestine, hepatopancreas, and muscle was performed on shrimp fed a plant-based diet, followed by weighted gene co-expression network analysis (WGCNA) and validation in an independent population. Phenotypic analysis revealed extensive variation in growth performance and RFI among individuals fed the plant-based diet. WGCNA identified four tissue-specific modules significantly associated with RFI, from which 20 hub genes were screened. Independent validation confirmed that seven genes were significantly differentially expressed between high- and low-feed-efficiency groups (q < 0.1): five in the intestine (LOC113811628, LOC113811631, LOC113824170, LOC113817752, LOC113811632) and two in the hepatopancreas (LOC113809216, LOC113820990). These genes are involved in mitochondrial function, energy metabolism, intracellular pH homeostasis, and nucleic acid metabolism, suggesting potential coordination between the intestine and hepatopancreas in response to plant-based diets. Collectively, these findings provide insights into the genetic basis of shrimp adaptation to plant-based diets and offer candidate molecular targets that may inform selective breeding efforts aimed at improving feed efficiency in P. vannamei. Full article

As aquaculture adopts more sustainable feed formulations, interest in functional feed additives has grown to help mitigate the health and performance challenges associated with low-marine-ingredient diets. This study evaluated the effects of dietary supplementation with a commercial blend of mono-, di-, and triglycerides of short- and medium-chain fatty acids (SCFAs and MCFAs; BalanGUT™ AQ P, BASF) on growth, health, and disease resistance to Vibrio anguillarum in juvenile gilthead sea bream (Sparus aurata) fed practical low fishmeal and fish oil diets. Over an 8-week trial, fish were fed diets containing 0.3%, 0.5%, or 1% of a glyceride blend of SCFAs and MCFAs (BalanGUT™ AQ P) or a Control diet without functional additive supplementation. Growth performance and feed utilization were not affected by the supplementation of SCFAs/MCFAs glycerides, although non-significant trends (p > 0.05) toward improved specific growth rate (up to 12%) and reduced feed conversion ratio (up to 17%) were observed in sea bream fed supplemented diets, particularly during the 4 initial weeks and at the highest inclusion level (1%). Moderate (0.5%) and high (1%) supplementation levels of SCFAs and MCFAs significantly improved survival following Vibrio anguillarum challenge, despite no significant changes being observed in general systemic innate immune markers, such as serum lysozyme or ACH50 activities. SCFAs/MCFAs supplementation, particularly at 0.3% or 0.5%, also modulated intestinal morphology, including thinner submucosa and smaller goblet cell area in the posterior intestine, suggestive of a more homeostatic mucosa and reduced basal inflammation when feeding a low-FM/FO-based diet. These results suggest that the protective effects of this SCFAs/MCFAs glyceride blend are mediated primarily through local rather than systemic immune modulation. Overall, this study supports the use of functional SCFAs and MCFAs glyceride blends as a functional strategy to promote resilience and health in fish fed sustainable, low-marine-ingredient diets. Full article

Background/Objectives: Low-fishmeal diets are widely adopted to improve sustainability in shrimp aquaculture, yet reduced palatability and metabolic stress frequently suppress feed intake and growth. We evaluated whether a crayfish (Procambarus clarkii) by-product protein hydrolysate (CBPH) could mitigate low-fishmeal-induced performance losses by modulating feeding-related metabolic signaling and gut microbiota features in Pacific white shrimp (Litopenaeus vannamei). Methods: In an 8-week feeding trial, 360 juveniles (initial body weight 0.46 g) were assigned to three diets (four replicates per diet): a commercial control (CON), a low-fishmeal diet (LFM), and LFM supplemented with 2% CBPH (CBPH). Growth, feed utilization, whole-body composition, hemolymph biochemical indices (TP, TG, GLU, AST, ALT), intestinal appetite-related gene expression (5-HTR, CART, CCK1R, D2-like, NPY), and intestinal microbiota profiles (full-length 16S rRNA sequencing, V1–V9, PacBio) were assessed. Results: Compared with the LFM group, CBPH supplementation increased feed intake and improved feed conversion, restoring final body weight and growth rates to levels comparable to CON. CBPH also alleviated low-fishmeal-associated metabolic stress, including reduced AST and ALT activities and lower glucose levels. The LFM diet induced upregulation of anorexigenic genes (5-HTR, CART, D2-like) and downregulation of NPY in the shrimp intestine, whereas CBPH supplementation reversed these transcriptional changes. In addition, microbiota richness indices (ACE and Chao1) were elevated by CBPH relative to LFM, accompanied by compositional shifts at the phylum and genus levels. Conclusions: CBPH effectively alleviated low-fishmeal-induced reductions in feeding and growth, accompanied by coordinated changes in feeding-related gene expression, systemic biochemical markers, and gut microbiota composition, supporting its potential as a functional ingredient to stabilize metabolic responses in low-fishmeal shrimp feeds. Full article

The growth performance of Penaeus monodon is often reduced when fishmeal is extensively replaced with terrestrial ingredients. This study evaluated the efficacy of a marine microbial biomass, NovaqPro™ (NQ), and inorganic mineral premixes in improving the performance of low fishmeal diets. Diets containing soybean meal, soy protein concentrate, and bloodmeal were formulated with fishmeal limited to 6%. Treatments included 10% NQ, an experimental inorganic mineral premix, a commercial mineral premix, and their combinations added to the low fishmeal control. A high fishmeal diet was also assessed as a benchmark of performance. NQ supplementation significantly improved shrimp growth, increasing weight gain by 78.7% compared with the low fishmeal control (2.77 vs. 1.55 g shrimp⁻¹) and numerically improved by 25.3% compared with the high fishmeal diet (2.21 g shrimp⁻¹). Similar responses were observed for FCR where NQ diets (1.47–1.68), as well as the high fishmeal diet (1.59), were superior to that of the control diet (2.02). Growth improvements were associated with increased feed intake and higher retention of protein and gross energy. In contrast, mineral premix supplementation did not improve growth, and weight gain was numerically reduced relative to the low fishmeal control. The NQ diet showed higher apparent digestibility of calcium, phosphorus, and magnesium compared with the high fishmeal diet. These results demonstrate that NQ is an effective mitigation strategy to reduce growth limitations associated with low fishmeal diets in P. monodon, without the need for additional inorganic mineral supplementation. Full article

The replacement of fishmeal with plant protein is widely regarded as a key strategy for sustainable aquaculture. However, carnivorous marine fish often show limited tolerance to fishmeal-free diets. Here, we investigated growth performance, hepatic physiological responses, and molecular mechanisms underlying adaptation to a soy protein concentrate-based diet (SPCD) in golden pompano (Trachinotus ovatus). An 8-week feeding trial was conducted under communal rearing conditions, followed by the phenotypic stratification of SPCD-fed fish into high- and low-growth subgroups. Growth performance, serum biochemical indices, and liver histology were assessed, and integrated transcriptomic and metabolomic analyses were performed on liver tissue. At the population level, the SPCD resulted in reduced growth, a lower feed intake, and decreased feed utilization efficiency compared with a fishmeal-based diet. Notably, marked inter-individual variation was observed: fish fed the SPCD exhibited significantly lower final body weights and a higher FCR compared with the FMD group (p < 0.001), and pronounced growth divergence was observed between the PB and PS subgroups, with a subset of SPCD-fed fish maintaining growth comparable to fishmeal-fed controls, whereas others exhibited severely constrained growth. Divergent phenotypes were associated with distinct hepatic alterations, including aggravated vacuolation, the enrichment of tight junction-related and immune regulatory pathways, and the broad reprogramming of lipid metabolism. Integrated multi-omics analysis identified arachidonic acid metabolism as the most significantly perturbed pathway, characterized by altered membrane phospholipid composition, the upregulation of RARRES3L, increased COX/LOX-derived eicosanoids, and the suppression of the CYP–EET branch. Collectively, these findings indicate that soy protein replacement induces coordinated hepatic structural and metabolic remodeling, with tight junction disruption and arachidonic acid metabolic reprogramming contributing to inflammatory imbalance and divergent growth phenotypes in T. ovatus. Full article

Spent coffee grounds (SCGs) represent a globally abundant agro-industrial byproduct with underexploited potential in circular bioeconomy applications. This study investigates the extraction, characterization and functional integration of SCG protein concentrate into aquafeed formulations for common carp (Cyprinus carpio). Protein was recovered through alkaline extraction followed by isoelectric precipitation, yielding a concentrate incorporated at 5% into a mixed plant and fishmeal diet produced by cold pelletizing. Compositional analysis performed by FT-NIR showed 33.6% crude protein, 7.24% lipids and 7.85% fiber, while ICP-OES confirmed substantial levels of essential minerals including Ca, P, K and Mg (15.3, 8.4, 10.4 and 2.3 g/kg). SCGs contributed bioactive compounds, with total polyphenols reaching 1.521 ± 0.065 mg GAE/g DM and an antioxidant capacity of 3.35 ± 0.03 mg TE/g DM. Pellets exhibited high water stability (91.8% retention after 30 min), and a short-term feeding test demonstrated strong acceptance by juvenile carp (91.2 ± 2.1%) consumption. Residual caffeine levels remained low (3.5 mg per g dry weight) and within safe exposure margins for freshwater fish. The results demonstrate the technical feasibility of incorporating SCG protein concentrate into compound aquafeeds without compromising pellet integrity or short-term palatability, while increasing feed-level antioxidant potential. However, the findings represent a proof-of-concept evaluation. Further research involving longer-term feeding trials, digestibility assessment, and amino acid profiling of complete diets is required to validate nutritional performance and optimize inclusion strategies for sustainable aquaculture. Full article

Quinoa germ meal (QGM) is a protein-rich by-product with potential as an alternative protein source; however, its effects on growth performance and intestinal health in marine carnivorous fish remain unclear. Juvenile turbot (Scophthalmus maximus) were fed five isonitrogenous (45.6% crude protein) and isolipidic (9.8% crude lipid) diets for 8 weeks: a fishmeal-based control diet (C) and four experimental diets in which fishmeal was replaced with QGM at 10% (Q10), 20% (Q20), 30% (Q30), and 40% (Q40). Growth performance, muscle proximate composition, intestinal histomorphology, and intestinal transcriptomic profiles were analyzed. Growth performance parameters, including final body weight, weight gain rate, specific growth rate, daily feed intake, and condition factor, decreased significantly with increasing QGM inclusion levels compared with the control (p < 0.05). Feed conversion ratio increased significantly only when replacement exceeded 30% (p < 0.05), while survival rate was unaffected (p > 0.05). Muscle crude lipid content was significantly reduced in all QGM-fed groups (p < 0.05), whereas crude protein, moisture, and ash contents were unchanged. Intestinal mucosal fold height increased in the Q30 and Q40 groups, while submucosal width decreased in the Q40 group (p < 0.05). Transcriptomic analysis revealed a dose-dependent increase in differentially expressed genes, mainly enriched in ribosome-related pathways, linoleic acid metabolism, and protein digestion and absorption. High dietary inclusion of QGM (>30%) impaired growth performance in juvenile turbot, whereas low inclusion levels (≤20%) exerted minimal adverse effects. Quinoa germ meal represents a potential alternative protein source, yet its effective utilization requires further optimization to maintain growth performance. Full article

The gut plays a central role in fish nutrition, immunity, and overall health, making it key in aquaculture research. The microbiota, crucial to gut function, is increasingly studied as an indicator of health and nutritional status. This study characterized the gut microbiota of juvenile meagre (Argyrosomus regius) (initial weight 4.6 ± 0.4 g) fed for seven weeks on diets in which fishmeal (FM) and fish oil (FO) were replaced by increased proportions of plant-based ingredients, with the aim of identifying microbial profiles associated with nutritional challenge. Fish were fed a FM/FO control diet (CTRL; 55.1% FM, 11.3% FO), a low FM/FO diet (CD; 15% FM, 7% FO), or a very low FM/FO diet (ED; 5% FM, 5% FO). Next-generation sequencing analysis of gut mucosa and digesta revealed no significant differences in alpha or beta diversity among different dietary groups. Firmicutes dominated all samples, particularly Bacilli, Mycoplasmatales, Mycoplasmataceae, and Mycoplasma. Significant differences were only observed in low-abundance taxa (<1%), with higher abundance of Thermoactinomycetales (p = 7.71 × 10⁻⁴), Thermoactinomycetaceae (p = 7.71 × 10⁻⁴), Kroppenstedtia (p = 1.70 × 10⁻³), and Pseudogracilibacillus (p = 0.039) in challenged groups. This study highlights the potential of low-abundance microbial groups as targets to establish gut health biomarkers in fish. Full article

Soybean meal causes health issues in piglets due to the presence of antigenic proteins. Although enzymatic treatment can break down antigenic proteins, subsequent high-temperature drying may impair amino acid (AA) digestibility via the Maillard reaction. This study evaluated whether the air-drying temperature affects the ileal AA digestibility of a novel reduced-sugar enzyme-treated soybean meal (ESM) in 25 kg pigs, using fishmeal as a high-digestibility reference. In two trials using pigs fitted with simple T-cannulas in the terminal ileum, ileal digestibility was assessed. In trial 1, a replicated 3 × 3 Latin square design with three diets (fishmeal, ESM, and a nitrogen-free diet; two pigs per diet) and three periods were used per square. Fishmeal showed greater apparent (82.50% vs. 45.01%) and standardized (86.60% vs. 48.86%) digestibility of crude protein and all amino acids than ESM dried at 130 °C. In trial 2, eight pigs were allocated to two diets in a two-period crossover design to compare the AA digestibility of ESM dried at high (130 °C; HtESM) and low (80 °C; LtESM) temperatures. LtESM exhibited greater apparent (82.24% vs. 52.40%) and standardized (86.37% vs. 56.47%) digestibility of crude protein and more amino acids than HtESM. Collectively, the drying temperature critically determined the AA digestibility of ESM, irrespective of its reducing sugar content. Full article

Low-fishmeal feed is increasingly being adopted across the global aquaculture industry. This study evaluated dietary Clostridium butyricum and alanyl-glutamine (Ala-Gln) supplementation in juvenile triploid rainbow trout (Oncorhynchus mykiss) with a low-fishmeal diet. Four diets were tested: basal diet (SBM, 15% fishmeal and 21.6% soybean meal), SBM + 0.5% C. butyricum (CB), SBM + 1.0% Ala-Gln, and SBM + 0.5% C. butyricum + 1.0% Ala-Gln (CB-AG). Fish were fed in 500 L tanks in recirculating aquaculture systems for 8 weeks (62.52 ± 0.47 g). Each group comprised three tanks, with each tank housing 30 fish. Then 10 fish per tank were challenged with Aeromonas salmonicida. CB-AG showed significantly higher weight gain and specific growth rates than the SBM group (p < 0.05). Mortality was significantly lower in CB-AG and AG than in SBM after A. salmonicida challenge. Histomorphology revealed significant differences (p < 0.05) between CB-AG and SBM in muscularis thickness, villus width, and height. SBM sections showed inflammatory infiltration and border damage were attenuated in supplemented groups. Serum malondialdehyde (MDA) and dioxygenase (DAO) were significantly lower in CB-AG than SBM (p < 0.05), while serum and hepatic lysozyme (LZM) and hepatic superoxide dismutase (SOD) were higher. Digestive enzymes indicated significantly higher trypsin and lipase activities in CB-AG (p < 0.05). CB-AG upregulated intestinal tight junction proteins and PepT1 and downregulated pro-inflammatory mediators. Combined 0.5% C. butyricum and 1.0% Ala-Gln inclusion effectively preserved growth performance, antioxidant capacity, gut microbiome homeostasis, and intestinal health in rainbow trout on low-fishmeal diets. Full article

This research explored the effects of supplementing taurine in a low-fishmeal diet on the growth, hepatic antioxidant capacity, muscle quality, intestinal health, and alleviation of inflammatory response of golden pompano (Trachinotus ovatus). Over an eight-week period, 300 juvenile fish (initial weight 9.4 ± 0.47 g) were randomly allocated into 12 net enclosures (1.0 × 1.0 × 1.5 m), with each treatment group comprising three replicate cages containing 25 specimens. The results demonstrated that an optimal taurine inclusion level of 1.0–1.5% significantly promoted growth, as evidenced by the increased weight gain rate (WGR) and specific growth rate (SGR). It also protected hepatic health by reducing alanine aminotransferase (ALT) activity and enhancing antioxidant capacity. Activation of the hepatic Nrf2/Keap-1/HO-1 signaling pathway increased the level of antioxidant gene expression, including catalase (CAT) and superoxide dismutase (SOD). In addition, the appropriate supplementation of taurine significantly down-regulated muscle hardness-related genes (cathepsin B (CatB) and cathepsin L (CatL)) and promoted the growth and differentiation of myoblasts, thus improving muscle quality. The chymotrypsin of fish fed the A25T10 diet was significantly higher than those in other groups (p < 0.05). The amylase (AMY) of fish fed the A25T15 diet was significantly higher than those in other groups (p < 0.05). The Chao1, Shannon, and Simpson of fish fed the A25T15 diet were significantly higher than those in other groups (p < 0.05). Proteobacteria were the most abundant in group A25T10. The relative abundance of Photobacterium rose in the A25RT10 group. In this study, taurine supplementation can down-regulate the expression of intestinal pro-inflammatory factors (interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8)) and up-regulate the expression of anti-inflammatory factor interleukin-10 (IL-10), enhance intestinal immunity, and improve intestinal digestion and absorption. Therefore, the addition of 1–1.5% taurine to low-fishmeal feeds can improve the growth performance of golden pompano. Full article

A limited supply and price shortages of fishmeal with the expansion of aquaculture make it necessary to seek alternative protein sources. Soybean meal (SM) has been the widely preferred replacer for fishmeal in fish diets. Nevertheless, this substitution, especially when given at high doses, potentially shows adverse impact on fish intestinal health. This study aimed to investigate the effect of replacing fishmeal with SM on intestinal health in olive flounder (Paralichthys olivaceus). A 56-day feeding trial was conducted with 450 juvenile fish (initial weight: 6.32 ± 0.01 g) randomly allocated to five diets with graded SM replacement: 0% (FM), 12% (SM12), 24% (SM24), 36% (SM36), and 48% (SM48). The results demonstrated that concentrations of glucose, total triglyceride, and low-density lipoprotein cholesterol increased, whereas total protein and high-density lipoprotein cholesterol contents, and lysozyme activity decreased in serum with increasing dietary SM levels. Meanwhile, total antioxidant capacity and superoxide dismutase activity significantly decreased at replacement levels exceeding 24%, accompanied by elevated malondialdehyde concentration (p < 0.05). Compared with the FM group, the SM24, SM36, and SM48 groups showed significantly reduced VH and increased lamina propria width (p < 0.05). Increasing dietary SM levels upregulated expression of genes related to endoplasmic reticulum stress (ERS) (chop, perk, and grp78), inflammation (tnf-α and il-6), and apoptosis (bax, casp3, casp6, and casp9), while downregulated anti-inflammatory cytokines (il-10 and tgf-β1) and tight junction-related genes (zo-1, zo-2, claudin-5, ocln, muc-13, and muc-15) in the intestine (p < 0.05). There were significant differences in the abundances of intestinal microbiota at both the phylum and genus levels among the FM, SM24, and SM36 groups (p < 0.05), but the clusters and microbiota composition of the SM24 group were more similar to those of the FM group. In conclusion, replacing 24% of fishmeal with SM induced intestinal dysfunction through evoking ERS, inflammation, barrier disruption, and microbial dysbiosis in olive flounder. Full article

Sustainable manure recycling in cold climates faces low efficiency and nutrient loss. This study evaluated housefly larva-pretreated manure (HL) for winter swine manure composting in East China, comparing it to sawdust-conditioned (CK2) and untreated manure (CK1). Larval pretreatment converted 12.71% of manure weight into biomass, assimilating 10.69% C, 30.55% N, 8.54% P, and 11.53% K. Harvested larvae contained 53.35% crude protein, with amino acids matching/exceeding fishmeal and soybean meal, while heavy metals were below safety limits. Theoretical annual larval protein yield per unit area (29,530 kg·mu⁻¹·year⁻¹) was 206.5 times higher than soybean crops. During composting, the HL treatment promoted early protease and catalase activation. This enzymatic synergy accelerated organic matter degradation and maturation, achieving a germination index of 147.67% by day 51. Coordinated nitrate and nitrite reductase activity in HL facilitated efficient denitrification, minimizing NO₂⁻ accumulation and N₂O emissions. Consequently, HL composting achieved faster stabilization, enhanced nutrient retention, and greater protein recovery compared to controls. These findings demonstrate that housefly larval pretreatment offers a climate-resilient and scalable strategy for winter manure management and protein valorization, with strong potential for applications in cold and resource-limited agricultural systems worldwide. Full article

Six dietary groups were supplemented with graded vitamin C (VC) levels: VC1 (control, 0.39 g/kg), VC2 (0.51 g/kg), VC3 (0.66 g/kg), VC4 (0.81 g/kg), VC5 (0.97 g/kg), and VC6 (1.11 g/kg). Largemouth bass (Micropterus salmoides) with an initial weight of 2.21 ± 0.00 g were fed these diets for 8 weeks to evaluate the effects of different VC levels on growth performance, immune response, and heat stress resistance. Heat stress was induced at a constant temperature of 33.00 ± 0.16 °C for one week. The VC3 and VC4 groups showed significantly improved growth performance (FBW, WGR, SGR) compared to VC1 (p < 0.05). VC4 exhibited lower ALT and AST levels before and after heat stress. Antioxidant capacity (T-AOC, GSH-Px, CAT) was significantly enhanced in VC3–VC5, with VC5 showing the highest after stress activity (except CAT). Expression of pro-inflammatory genes (nf-κb, il-8) was downregulated in VC4 and VC5, while anti-inflammatory il-10 was upregulated in VC4 after stress. Apoptosis-related genes (bcl-2, caspase, bax) and TUNEL assays indicated the strongest anti-apoptotic effects in VC3 and VC4 under heat stress (p < 0.05). These findings suggest that VC supplementation in low-fishmeal diets enhances growth, immune response, apoptosis resistance, and acute heat stress tolerance in fish. Full article

As aquaculture expands, there is a growing demand for sustainable and environmentally friendly feed ingredients that can replace conventional fish meal while maintaining high biological value and digestibility. The use of fishmeal has contributed to overfishing, making it an increasingly limited and unsustainable resource. Tenebrio molitor (TM) is emerging as a sustainable alternative to fishmeal (FM) in aquaculture diets, gaining attention due to its balanced protein composition profile and low environmental footprint. This review critically analyses data from the literature on the use of TM meal as a substitute for fish feed ingredient, focusing on its effects on growth performance, physiological status, and histological changes in the digestive and muscular systems. The influence on the physicochemical and sensory quality of fish meat is also evaluated. The discussion highlights both the benefits and possible adverse effects, such as intestinal inflammation or changes that may occur, depending on the replacement level. The paper presents recommendations and strategies to mitigate these effects, including the use of dietary supplements or partial replacement schemes. Overall, this paper emphasises the promising potential of TM as a sustainable alternative to FM in aquaculture feed, while highlighting the need for further research into the long-term effects, involved metabolic pathways, and standardisation of insect meal production. This review provides valuable insight into the physiological changes that may occur, particularly at high inclusion levels. As TM is utilized in both human nutrition and aquaculture diets, monitoring its physiological effects in fish is essential, since any alterations may have implications for human food safety. Full article