Search Results (280)

Tryptophan has been shown to affect fish feed intake and growth performance. Moreover, it is the precursor of several bioactive molecules such as serotonin, which can be converted into melatonin. Melatonin is a potent antioxidant that directly neutralises free radicals and reduces oxidative stress. Diets rich in tryptophan may contribute to reduced oxidative stress, potentially through its role as a precursor of serotonin and melatonin. In this study, three diets containing different contents of tryptophan: 0.5 (Trip1), 0.6 (Trip2) and 0.8% (Trip3), were tested in triplicate in 112-day-old meagre with an initial weight of 32.6 ± 3.4 g and 14.4 ± 0.5 cm length for 56 days. Although the results showed no significant differences for growth and FCR between treatments, there was a tendency toward increased growth and a decrease in FCR in meagre fed higher levels of tryptophan. The main protein degradation systems in the liver and white muscle were evaluated. The activity of the tested proteases in the muscle was unaffected by dietary tryptophan levels. A decrease in oxidative stress was also observed as the level of tryptophan in the diets increased, although not statistically significant. A trend of decreasing superoxide dismutase, catalase, and selenium-independent glutathione peroxidase levels in tryptophan-rich diets was also observed. Full article

Our previous studies found that lipid emulsifiers can promote the absorption and deposition of liposoluble pigments in shrimp. The present study aimed to further investigate the effects of liposoluble pigments lutein (LUT) and lycopene (LYC), and their combination with lysophospholipids (LPL), on the growth performance, body coloration, and lipid composition of Pacific white shrimp Penaeusvannamei. Five diets were formulated: a control diet (Control), Control + 0.02% lutein (LUT), Control + 0.02% lycopene (LYC), LUT + 0.1% LPL (LUT + LPL), and LYC + 0.1% LPL (LYC + LPL). The feeding trial lasted for 8 weeks. There were no significant differences in shrimp growth and body composition among all groups. Both LUT and LYC increased the redness (a*) and yellowness (b*) of cooked shrimp. LPL synergistically enhanced the pigmentation-improving effects of LUT but weakened those of LYC. Additionally, LYC decreased the redness and yellowness of raw shrimp. Both LUT and LYC reduced the contents of saturated fatty acids and EPA while increasing the DHA content; LPL further enhanced this modulatory effect. In conclusion, LPL acts synergistically with LUT to improve the body coloration and modify the fatty acid composition of Pacific white shrimp, but its effect with LYC is limited. 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

In this study, the effects of different feeds provided during the initial feeding period of Trichogaster lalius (dwarf gourami) larvae on larval survival were evaluated. Larvae reared under laboratory conditions were assigned to four dietary treatments (EY: boiled chicken egg yolk, RO: live rotifers, IN: infusoria, SP: live Spirulina) during days 3–5 post hatching, after which all groups were enriched with live Artemia on days 5–10. A total of 4800 larvae were distributed across 16 treatment groups. On day 10, larval abundance and total length (mm) were recorded, and survival percentages were subsequently calculated. The pooled survival rates at the end of the experiment were 95.50 ± 4.05 for EY, 95.50 ± 2.53 for RO, 58.58 ± 8.88 for IN, and 77.25 ± 10.23 for SP. Statistical analysis revealed no significant differences in survival between the EY and RO groups (p > 0.05). In contrast, significant differences were observed between the IN group and the SP group, as well as between IN and the remaining treatment groups (p < 0.05). Moreover, no significant differences in total length were detected among the 16 groups at the end of the experiment (p > 0.303). Overall, the findings suggest that, under the present experimental conditions, larval survival of T. lalius was higher in the egg yolk and rotifer feeding treatments than in the infusoria and live Spirulina groups. Full article

Prophylactic antibiotic use in intensive aquaculture promotes antimicrobial resistance, necessitating the development of microbial-based interventions. This study evaluated the individual, complementary, and synergistic effects of Bacillus subtilis natto (BSN) and Lactobacillus plantarum (LP) on the physiological performance and intestinal microecology of juvenile Japanese flounder (Paralichthys olivaceus). Over a 60-day trial, juveniles (initial weight: 5.81 ± 0.03 g) received a basal diet (CON) or a diet supplemented with 10⁷ CFU/g of BSN, LP, or both (BSN + LP). The BSN + LP consortium elicited complementary improvements in final body weight (21.39 ± 0.75 g vs. 18.66 ± 0.44 g in CON) and feed conversion efficiency (p < 0.05). Transcriptomic analysis revealed synergistic upregulation of digestive proteases (trypsin, chymotrypsin). Notably, an in pro-inflammatory markers (IL-1β, TNF-α) was counterbalanced by substantial upregulation of anti-inflammatory cytokines (IL-10, 5.65-fold; TGF-β1, 4.48-fold), suggesting the induction of mucosal tolerance rather than pathological enteritis. High-throughput 16S rRNA sequencing showed that the control cohort had a potential baseline microbial, characterized by a high relative abundance of Proteobacteria. BSN + LP administration significantly altered this microbial community into a fermentative eubiosis enriched in Firmicutes and Bacteroidota. Correlation network analyses confirmed negative interaction dynamics: increased abundance of Lactobacillus, Bacteroides, and Muribaculaceae was negatively correlated with baseline pathobiont abundance. These findings indicate that co-administration of BSN and LP hypothetically enhances metabolic energy harvest via short-chain fatty acid-producing taxa, strengthens the gut–immune axis, and competitively mitigates opportunistic pathogens. Full article

A 10-week feeding experiment was conducted to evaluate the effects of replacing fishmeal with cricket meal on the productive performance and transcriptional responses of genes related to nutrient metabolism and growth of blue tilapia (Oreochromis aureus). Five conventional tilapia feeds were formulated to replace fishmeal with cricket meal. Control diet (CD) was formulated with 20% fishmeal, and four diets gradually replaced fishmeal with cricket meal at 20, 40, 60, and 80% (D1–D4). A total of 200 fingerling tilapia (2.00 ± 0.09 g) were randomly distributed into 20 tanks (10 fish/tank), with four replicates per dietary treatment. The results showed that fish fed CD and D1 had higher growth performance values than those fed D2–D4. The feed conversion ratio (FCR) was significantly better in fish fed CD and D1 compared with fish fed D2–D4. The survival rate was similar for all treatments. The transcriptional response of genes related to nutrient digestion, absorption, and transport; lipid metabolism; and the somatotropic axis was marked downregulated in fish fed D2 and D4, whereas in fish fed D3, it exhibited a unique compensatory regulation across most pathways, likely sustained by its higher dietary lipid content. Although cricket meal did not prevent the metabolic effects associated with high soybean meal inclusion, survival remained high across all treatments. Cricket meal can replace up to 20% of the fishmeal in the feed for blue tilapia fingerlings, with soybean meal as the main protein source. Full article

Monosex all-male culture of the giant freshwater prawn (Macrobrachium rosenbergii) maximizes aquaculture yield due to a male growth advantage, but direct hormonal treatment of grow-out populations poses significant food safety risks. This study evaluated the efficacy of dietary 17β-estradiol (E2) in inducing functional neo-females from a fully all-male postlarval population to support an indirect monosex seed production strategy. All-male postlarvae were fed diets supplemented with E2 at concentrations of 0, 50, 100, 150, and 200 mg/kg for 36 days, followed by a 150-day hormone-free post-treatment period to assess growth performance, feminization rates, and gonadal histology. E2 administration successfully induced feminization across all treatments, reaching a peak rate of 35.5% at 150 mg/kg, whereas the control group remained entirely male. During the 36-day treatment period, E2 supplementation transiently enhanced specific growth and survival rates but concurrently reduced feed conversion ratios. Notably, these physiological differences disappeared completely over the 150-day post-treatment phase. Histological assessments confirmed that E2-induced neo-females exhibited normal oogenesis, with gonadosomatic index (GSI) values and oocyte diameters similar to those of wild-caught females. This establishes a definitive, physiologically safe, and non-surgical protocol for producing the neo-female broodstock necessary to sustain high-yield commercial monosex populations. Full article

This study compared the effects of dietary Lactobacillus plantarum (Lpl) and selenium-enriched L. plantarum (Lpl_se) on the growth, hepatic antioxidant capacity, and intestinal microbiota of juvenile largemouth bass (initial weight 12.50 ± 0.81 g). Following a 58-day trial in an indoor rearing system, data were analyzed using one-way ANOVA followed by Tukey’s HSD test. Results showed that both Lpl and Lpl_se significantly improved growth versus the control (Weight Gain Rate: 379.82% and 387.18% vs. 326.56%; p < 0.05). Both supplements significantly elevated hepatic antioxidant enzymes (SOD, CAT, GSH) and reduced malondialdehyde (MDA) levels (p < 0.05). Notably, these macroscopic parameters showed no statistical differences between the two probiotic treatments. However, 16S rRNA sequencing revealed distinct metabolic strategies. While both treatments enriched intestinal Lactobacillus, Lpl_se uniquely upregulated energy-harvesting and synthetic pathways (glycolysis and lysine biosynthesis), corroborated by increased intestinal glycogen synthase activity. In conclusion, while selenium enrichment did not further improve macroscopic growth statistically, it differentially modulated the intestinal functional profile towards enhanced carbohydrate and amino acid metabolism, presenting an alternative host nutrient assimilation strategy. Full article

To investigate the effects of three alternative protein sources—Hermetia illucens larvae meal (HIM), Chlorella meal (CM) and stickwater meal (SWM)—on the vitellogenin in female largemouth bass (Micropterus salmoides), these protein sources were used to replace 0% (control group, FM; containing 40% fishmeal), 25% and 50% of the fishmeal in the diet. A total of seven isonitrogenous and isolipidic diets were formulated (FM, 25% HIM, 50% HIM, 25% CM, 50% CM, 25% SWM and 50% SWM). The healthy female fish with an initial body weight of 353.57 ± 28.12 g were fed the experimental diets for eight weeks. The results showed that the viscerosomatic index, gonadosomatic index and oocyte diameter of broodstock in the 50% HIM group were significantly higher than those in the FM group. The 50% HIM group showed the highest rate of stage IV oocytes and the lowest share of stage II oocytes. Hepatic vitellogenin (Vg) mRNA expression was significantly upregulated in the 50% HIM group, whereas ovarian mRNA expression of Vg and vitellogenin receptor (VgR) was significantly upregulated in the 25% SWM and 50% SWM groups. In conclusion, replacing 50% of dietary fishmeal with Hermetia illucens larvae meal can promote ovarian development in largemouth bass broodstock by increasing the gonadosomatic index and the expression of genes involved in vitellogenin synthesis. Full article

This study aimed to investigate the effects of dietary lipid levels on growth performance and transport stress resistance in large-sized channel catfish (Ictalurus punctatus). Four experimental diets were formulated with fat levels of 7.5% (control), 10.0%, 12.5%, and 15.0%, using soybean oil as the lipid source. Each diet was assigned to four replicate groups in a 110-day feeding trial, with fish averaging 600.61 ± 1.33 g at the start. Results showed that increasing dietary fat enhanced weight gain rate (WGR) and specific growth rate (SGR), with the 15.0% fat group achieving the best growth performance and the lowest feed conversion ratio (FCR), significantly lower than the control (p < 0.05). However, fish fed diets containing 12.5% and 15.0% fat exhibited disorganized hepatocyte arrangement, unclear cell boundaries, and hepatic vacuolization. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities increased initially and then declined with rising fat levels, with the highest values observed at 12.5% fat, significantly exceeding those in the control group (p < 0.05). Furthermore, after simulated transport, the incidence of skin congestion and hemorrhage increased with dietary fat level. Collectively, while higher fat levels improved growth, excessive fat (≥12.5%) compromised liver health and stress resilience. Therefore, a dietary fat level of 10.0% is recommended to balance optimal growth, hepatic integrity, and transport tolerance in I. punctatus. Full article

Understanding how different pre-slaughter and slaughter procedures modulate physiological and neurochemical pathways in European sea bass (Dicentrarchus labrax) remains essential for welfare-oriented aquaculture. This study comparatively evaluated six procedures: clove oil and 2-phenoxyethanol anaesthesia, percussive stunning, asphyxiation in ice slurry or on solid ice, and clove oil anaesthesia followed by ice slurry, using plasma glucose and whole-brain monoaminergic indices as integrative physiological response indicators. Ninety-six fish were analysed. Ice-based asphyxiation and 2-phenoxyethanol exposure were associated with the highest plasma glucose concentrations, whereas clove oil and percussive stunning showed comparatively lower values. Dopaminergic and serotonergic turnover ratios (DOPAC/DA; 5-HIAA/5-HT) increased sharply under ice and 2-phenoxyethanol treatments, indicating increased monoaminergic activity under these procedures. Multivariate analyses (MANOVA, PCA) distinguished anaesthetic-based treatments from ice-based methods according to their combined neurochemical profiles. Although correlations between glucose and monoaminergic indices were modest, they were statistically significant and consistent with coordinated metabolic–neurochemical adjustments. Overall, DOPAC/DA and 5-HIAA/5-HT ratios emerged as sensitive and mechanistic biomarkers capable of differentiating slaughter procedures according to their relative physiological impact. These findings support the integration of metabolic and neurochemical indicators in welfare assessment and may contribute to evidence-based refinement of humane slaughter protocols in Mediterranean aquaculture systems. Full article

This research was conducted to evaluate the impacts of pomegranate (Punica granatum L) peel extract (PPE) on the mold growth and moisture content in pellet feeds, as well as the biochemical indicators in tissues and organs of fish. Firstly, six types of pellet feeds were formulated by adding 0% or 0.5% of pomegranate peel powder (PP), petroleum ether extract (PEE), ethyl acetate extract (EAE), ethanol extract (EE), or aqueous extract (AQE) of PP. Moisture content was determined by air-drying 10 g of wet pellet feed from each treatment at 60 °C for 48 h in uniform-sized Petri dishes. Mold growth was evaluated by homogenizing 15 g of 12-week stored pellet feed with 15 mL of purified water, incubating at 25 °C for 4 days, and recording mold growth. The results indicated that PP, PEE, EE, and AQE reduced the mold growth in pellet feeds (p < 0.05). PP, EAE, EE, and AQE increased the moisture content in pellet feeds. Among all additives, EE has the strongest effects on the mold growth and moisture content in feeds (p < 0.05). According to regression analysis of mold and moisture levels, the optimal EE supplementation levels in pellet feeds were evaluated to be 1.284% and 1.485%, respectively. Then, 420 carp (Cyprinus carpio var. Jian, mean initial weight 12.01 ± 0.53 g) were fed diets formulated with EE at graded inclusion levels (0, 0.3, 0.6, 0.9, 1.2, 1.5, and 1.8%) over a 15-day period. The findings indicated that dietary EE improved the digestive and absorptive function in carp (p < 0.05), and this improvement was closely correlated with the upregulated activities of digestive and absorptive enzymes and the strengthened antioxidant capability in carp’s digestive tissues. Regression analysis of feed intake rate indicated that the optimal EE level suitable for carp is 0.906%. Furthermore, dietary EE enhanced the respiratory capacity by improving functional metabolic enzyme activity and antioxidant defense in the respiration-related tissues and organs of fish (p < 0.05). In summary, supplement EE increases the moisture content, inhibits the mold growth in pellet feeds, and improves the respiratory, digestive, and absorptive functions in fish, providing a valuable insight for PEE use as a naturally functional raw material in fish feeds. Full article

The search for sustainable alternatives to fishmeal (FM) in aquafeeds represents a major challenge for modern aquaculture. This study evaluated the effects of replacing 35% of FM with defatted Hermetia illucens larvae meal (HIM35) in diets of gilthead seabream (Sparus aurata) reared under full-scale commercial offshore farming conditions. Fillet nutritional quality, fatty acid and amino acid profiles, mineral composition, and microbiological stability during refrigerated storage were assessed. Dietary HIM35 significantly modified the fatty acid profile, increasing saturated fatty acids, particularly lauric and myristic acids, and n-6 polyunsaturated fatty acids. Despite reductions in eicosapentaenoic and docosahexaenoic acids (EPA and DHA), total PUFA and lipid health indices remained within recommended ranges and EPA + DHA levels were above 8%, supporting both fillet nutritional value and fish physiological requirements. Enzymatic indices based on product-to-precursor fatty acid ratios suggested reduced Δ5 + Δ6-desaturase activity. The amino acid profile showed increases in selected essential and non-essential amino acids, while overall protein quality was preserved. HIM35 fillets showed lower sodium and higher zinc contents, whereas increased aluminum levels warrant further investigation. Microbiological analyses confirmed the absence of foodborne pathogens and no effects on spoilage dynamics. Overall, HIM35 represents a safe and effective partial replacement for FM supporting sustainable aquafeed strategies. Full article

This study investigated the effects of dietary lysophospholipids on growth performance, hepatic lipid metabolism, intestinal health, and dietary lipid levels of largemouth bass. The 56-day experiment included five groups: CON (0% lysophospholipids), LL50 (0.05% lysophospholipids), LP50 (0.05% lysophospholipids—0.5% oil), LP100 (0.1% lysophospholipids—1.0% oil), and LP200 (0.1% lysophospholipids—2.0% oil), with 3 replicates (30 fish/replicate) per group. The results showed that compared with the CON group, dietary supplementation of 0.05% lysophospholipid had no significant effect on the growth performance of largemouth bass, but increased the crude protein content and decreased the crude lipid content in the whole body. An amount of 0.05% lysophospholipid improved hepatic lipid utilization efficiency. Specifically, this supplementation level promoted serum lipid transport (increased serum HDL-C content and decreased triglyceride and LDL-C contents), and enhanced hepatic lipid metabolism by regulating the expression of lipid metabolism-related genes (fas, hsl, and acc) and the levels of lipid metabolites (phosphatidylcholine and fatty acids), thereby reducing hepatic triglyceride content. In addition, 0.05% lysophospholipid improved intestinal health by increasing lipase activity and intestinal villus height, up-regulating the expression of the anti-inflammatory gene (tgf-β1) and tight junction protein genes (claudin-1, claudin-4, and zo-1), and down-regulating the expression of the pro-inflammatory gene (tnf-α). In terms of dietary lipid reduction, supplementation with 0.1% lysophospholipid allowed a 1% reduction in dietary lipid level without affecting the growth performance of largemouth bass, whereas at the same level of lysophospholipid supplementation, a 2% reduction in dietary lipid level resulted in decreased growth performance of largemouth bass. These findings provide theoretical support for the practical application of lysophospholipids, and demonstrate that reducing dietary lipid inclusion by adding lysophospholipids helps to reduce feed costs and improve aquaculture economic benefits. Full article