Search Results (52)

Selenium (Se) is an essential trace element critical for animal growth and immune function. This study investigated the dietary selenium requirement of juvenile large yellow croaker (Larimichthys crocea) through an 8-week feeding trial. Five experimental diets were formulated by supplementing a basal diet with selenium polysaccharides (Se-PS) at 0, 20, 30, 40, and 50 mg/kg, resulting in analyzed Se concentrations of 0.35, 0.54, 0.71, 0.93, and 1.11 mg/kg, respectively. The results demonstrated that growth performance and feed efficiency improved with increasing dietary selenium, peaking at 0.93 mg/kg before declining at higher levels. Antioxidant enzyme activities—superoxide dismutase (SOD) and catalase (CAT)—in serum and liver tissues exhibited a dose-dependent increase, reaching maximal levels at 1.11 mg/kg. Conversely, malondialdehyde (MDA), a marker of oxidative stress, progressively decreased in both serum and liver, attaining its lowest concentration at 1.11 mg/kg, though this did not differ significantly from the 0.93 mg/kg group (p = 0.056). Tissue selenium accumulation was highest at these optimal dietary levels. Based on the growth performance, oxidative stress response, and tissue selenium retention, the recommended dietary selenium requirement for juvenile large yellow croaker is 0.93 mg/kg. These findings highlight the importance of optimal Se supplementation in aquafeeds to enhance growth and physiological health in farmed fish. Full article

Shrimp farming is practiced worldwide in tropical and subtropical regions, where shrimp often experience suboptimal temperatures during part of the production cycle, resulting in slower growth. A concentrated functional palatability enhancer (FPE) containing a mixture of chemoattractants was tested. A 12-week experiment at a suboptimal temperature (22 °C) was conducted with Penaeus vannamei (3.25 ± 0.02 g) in a clear water system (400 L with 40 shrimp per tank) with flow-through seawater. A standard diet was supplemented with 0, 1, and 2 g kg⁻¹ of FPE (STD, STD+1, and STD+2) with four replicates for each one. The inclusion of 1 g kg⁻¹ of FPE (STD+1) significantly increased the average final weight by 11.24% and weekly weight gain by 14,00% when compared to STD. The highest tested dose (2 g kg⁻¹) did not result in further improvement in growth performance compared to the control. In addition, the total hemocyte count (THC) remained at an optimal level for the species in the STD+1 treatment under suboptimal temperature conditions compared to the other treatments. We also observed a decrease in Vibrio spp. bacterial counts in STD+1 compared to STD+2. Therefore, the lowest tested dose was shown to positively influence the rearing of P. vannamei at suboptimal temperatures. Full article

The need to maximize aquaculture production while addressing environmental and food security challenges posed by climate change has driven research towards the development of functional aquafeeds that enhance performance and immunity in farmed species. However, exposure to dietary and environmental stressors affects marine organisms, altering key metabolic pathways best understood through high-throughput “omics” tools. This study assessed the effects of Asparagopsis taxiformis supplementation on central metabolic pathways by analyzing changes in primary metabolite levels in the liver of farmed Diplodus sargus under optimal and suboptimal temperature conditions. Results showed that seaweed supplementation had a beneficial effect on the fish’s primary metabolome; however, inclusion levels and rearing conditions played a crucial role in determining outcomes. While 1.5% supplementation maintained a balanced primary metabolome under optimal temperature conditions, 3.0% supplementation most effectively mitigated the adverse effects of acute thermal stress during a marine heatwave. These findings highlight the nutritive and functional potential of A. taxiformis supplementation in aquafeeds for marine omnivorous fish species and emphasize the importance of evaluating functional aquafeeds under suboptimal rearing conditions. Overall, our results demonstrate the value of metabolomics in elucidating the molecular basis underlying biological pathways in farmed marine fish and optimizing production through climate-smart dietary strategies. Full article

The use of postbiotics for dietary fortification in aquaculture is gaining increasing attention due to their potential immunomodulatory and gut health benefits. In this study, we evaluated the effects of postbiotics derived from Vibrio proteolyticus DCF12.2 on intestinal histology, microbiota composition, and the expression of genes related to epithelial integrity and inflammation in juvenile gilthead seabream (Sparus aurata). Fish were fed either a control (CRTL) diet or the postbiotic-supplemented diet (VP) for 62 days. At the end of the feeding trial, a lipopolysaccharide (LPS) challenge was conducted to evaluate the immune response in fish. Histological analysis revealed a healthy mucosa in both groups, though fish fed the VP diet reduced fold height and mucosal layer thickness, alongside a significant increase in goblet cells. Microbiota profiling indicated higher alpha diversity and significant shifts in community composition in the VP group, including enrichment of potentially beneficial genera (Pseudomonas, Sphingomonas) and depletion of opportunistic taxa (Enterococcus, Stenotrophomonas). After the feeding trial, fish fed the VP diet exhibited downregulation of pro-inflammatory markers (tnfα, cox2). Following LPS challenge, cdh1—a key epithelial adhesion protein required for maintaining intestinal barrier integrity—expression was upregulated significantly in the VP group, suggesting enhanced epithelial resilience. These findings demonstrate that dietary fortification with V. proteolyticus-derived postbiotics supports mucosal health as well as modulates the intestinal microbiota and immune responses in gilthead seabream juveniles, offering a promising strategy for functional aquafeed development in sustainable aquaculture. Full article

Marine heatwaves (MHWs) are an emerging challenge for aquaculture, increasing the frequency and severity of disease outbreaks in farmed fish, weakening immunocompetence and compromising overall health and survival. As climate change stressors intensify, there is an urgent need for cost-effective and environmentally friendly strategies to enhance fish resilience. This study investigated the efficacy of Laminaria digitata, a brown macroalga, included in aquafeeds as powder (0.3% and 1.5%) or extract (0.3%) in improving the stress response of juvenile gilthead seabream (Sparus aurata) co-exposed to Vibrio harveyi infection during a category III MHW event. Under control conditions, L. digitata supplementation maintained or improved fish growth performance and overall well-being. After MHW exposure, the 1.5% powdered and 0.3% extract diets were more effective in mitigating thermal stress, reducing liver oxidative stress and lowering plasma cortisol levels. In infected fish, these diets improved resistance to V. harveyi, with reduced cortisol and alanine aminotransferase concentrations indicating hepatoprotective properties, and lower lipid peroxidation and decreased antioxidant enzyme activities reflecting an amplified capacity to counteract oxidative stress induced by inflammation. Overall, L. digitata is a promising aquafeed supplement, with the 1.5% powdered form offering a cost-effective alternative to the extract without compromising efficacy. Full article

Extreme weather events, such as marine heatwaves (MHWs), pose serious threats to the aquaculture sector, facilitating the occurrence of disease outbreaks and compromising farmed animals’ welfare and survival. Hence, finding eco-innovative strategies to improve animal immunocompetence is essential to assure aquaculture’s sustainability and resilience in a rapidly changing ocean. This study evaluated the immunostimulatory potential of Laminaria digitata powder (0.3% and 1.5%) and extract (0.3%) in juvenile gilthead seabream (Sparus aurata) exposed to a Vibrio harveyi outbreak during a Category III MHW event (T = 25.7 °C). Overall, L. digitata supplementation did not significantly affect fish immunocompetence under optimal rearing conditions (T = 21.4 °C; no infection), nor did it induce any adverse effects. However, both the powder (1.5%) and extract (0.3%) forms of L. digitata supplementation effectively mitigated the negative impacts prompted by the MHW and Vibrio harveyi infection—evidenced by improvements in fish health indicators, hematological parameters, leukocyte viability, granulocyte proportions, and reductions in peroxidase activity and immunoglobulin M levels. From an economic standpoint, supplementation with 1.5% L. digitata powder emerged as the most promising strategy, offering a practical balance between effectiveness and affordability for large-scale applications. These findings highlight the potential of L. digitata as an immunostimulatory aquafeed supplement, with promising benefits for fish health and resilience under adverse rearing conditions. Full article

To address the growing global demand for aquatic protein and the need for sustainable aquaculture, this study explored Aspalathus linearis tea extract as a novel feed additive for Oreochromis mossambicus larvae. Over an eight-week feeding trial, the efficacy of diets supplemented with 30% fermented or green rooibos extract was assessed against a control. Both fermented and green rooibos treatments significantly (p < 0.05) enhanced larval growth, evidenced by improved weight gain and feed conversion ratios (fermented: 1.50 ± 0.25; green: 1.41 ± 0.07). Notably, A. linearis extracts also demonstrated genoprotective potential, as indicated by a marked reduction in micronucleus frequency, most likely attributed to their abundant phenolic compounds. These findings demonstrate that rooibos extract, especially the green variety, can improve growth performance and feed utilization, and also provide genoprotective benefits. The superior outcomes in growth and feed conversion are likely due to the bioactive phenolic compounds, which may enhance palatability, gut health, and nutrient absorption, rather than macronutrient content. This positions rooibos extract as a promising natural functional additive for aquafeed, offering a sustainable strategy to enhance tilapia farming productivity and resource utilization. However, further research is necessary to uncover specific molecular mechanisms, conduct in-depth analyses of gut health and immune responses, and evaluate effects on product quality to facilitate its sustainable and effective integration into aquaculture practices, thereby contributing to both fish health and food security. Full article

Medicinal plants are rich in nutrients and bioactive compounds, making them potentially suitable for use as chemotherapeutic agents and as additives in aquafeed. Our research evaluated the effects of purslane (Portulaca oleracea) extract supplemented in sunflower-based diets on the growth, carcass composition, blood indices, mineral content, liver antioxidant enzyme profile, and immune response in Cirrhinus mrigala (8.26 ± 0.07 g/fish). The juveniles were fed one of seven different diets—T₀ (no extract), T₁ (0.5%), T₂ (1%), T₃ (1.5%), T₄ (2%), T₅ (2.5%), and T₆ (3%)—twice daily, at a feeding rate of 5% of their live body weight. They were stocked in V-shaped steel tanks for 90 days, with 15 juveniles per tank and three replicates per dietary treatment. The results of this research revealed that 1–2% purslane extract substantially enhanced growth indices in fish (p < 0.05). Furthermore, the supplementation of 1–2% dietary purslane extract in the diet significantly lowered fat content and improved protein content (p < 0.05) compared to the diets with 0% and 3% purslane extract inclusion. The outcomes also indicated that the hematology and mineral content in the bodies of juveniles were significantly improved (p < 0.05) at all levels of purslane supplementation, relative to the control groups with 0% and 3% inclusion levels. Moreover, the administration of purslane extract markedly increased the liver antioxidant profile, including glutathione peroxidase, superoxide dismutase, and catalase. Additionally, there was a notable reduction in malondialdehyde levels when fish were fed diets having 1% and 1.5% extract. The findings of this study also revealed improvements in immunological markers, characterized by increased lysozyme activity and elevated total globulin levels. The current research suggests that supplementing C. mrigala diets with 1% purslane extract optimally enhances growth and immunity. Full article

The rising scarcity and cost of fishmeal due to overfishing and environmental challenges demand alternatives. Black soldier fly (Hermetia illucens) larvae (BSFL) meal, with its nutritional value, shows promise as a sustainable supplement for aquaculture species. This study evaluated the effects of BSFL meal supplementation on growth performance, survival, feed conversion efficiency, and meat quality in juvenile swamp eels (Monopterus albus) initially weighing 4.0 ± 0.5 g. The eels were fed diets with 0% (control), 10%, 30%, and 50% BSFL meal for three months. Growth performance was assessed using the absolute growth rate (AGR) and the specific growth rate (SGR). Feed conversion ratios (FCRs), survival rates, and meat quality metrics, including fillet percentage, crude protein, and moisture content, were analyzed. Statistical differences among groups were evaluated using one-way ANOVA followed by Tukey’s post hoc test for pairwise comparisons. The 30% BSFL group exhibited superior performance, achieving the highest AGR and SGR (p < 0.05) and the lowest FCR (2.33 ± 0.03). Fillet percentage was highest in this group (27.3% ± 0.7%), with no significant differences in crude protein or moisture content. Survival rates were consistent across treatments (75.2–76.0%, p > 0.05). These results confirm that 30% BSFL supplementation optimally enhances productivity and meat quality in swamp eels, highlighting BSFL meal’s potential as a sustainable aquafeed alternative. Full article

The aquafeed industry evolved alongside fish farming, utilizing scientific and technological advancements to incorporate a variety of feed additives, supplements, and alternative ingredients in the nutrition and feeding of fish in aquaculture. These advances played a significant role in improving the production, health, and welfare of farmed fish. Recent research in Brazil highlighted the importance of using fish feed additives, such as vitamins, minerals, and amino acids, to ensure that farmed fish receive all the necessary nutrients for growth and health. Functional additives can enhance the immune system, boosting disease resistance and promoting the overall health of fish. Antimicrobial and antiparasitic additives help prevent and treat infections and infestations, reducing the occurrence of disease outbreaks. Additionally, some additives improve feed digestibility, leading to better nutrient absorption and reduced feed requirements. Overall, nutritional strategies are essential for optimizing fish farming practices in Brazil and globally, promoting fish health and sustainability in the industry. This review emphasizes the significance of certain additives, supplements, and ingredients strategically incorporated into experimental feeds for research in Brazilian fish farming. It also underscores the necessity for ongoing research. There is a noticeable trend towards developing more sustainable and efficient feeds, which is essential for the future of sustainable aquaculture. The goal is to minimize environmental impacts while maintaining economic viability in aquaculture operations. Full article

As the global demand for aquafeed ingredients continues to rise, sourcing sustainable alternatives is crucial for aquaculture industries. This study aimed to explore the potential of enzymatic hydrolysate as a substitute for traditional fishmeal and soybean meal in diets for juvenile sea cucumbers (Apostichopus japonicus). Three isonitrogenous (15% crude protein) and isolipidic (2.4% crude lipid) diets were formulated: a control diet containing 10% fishmeal and 5% soybean meal and two experimental low-fishmeal (8%) and low-soybean meal (0%) diets, supplemented with either 8% enzymatically hydrolyzed fish stickwater (EFS) or 8% enzymatically hydrolyzed chicken pulp (ECP), designated as Control, EFS, and ECP, respectively. Juvenile sea cucumbers (initial body weight, 0.25 ± 0.01 g) were fed these diets for 84 days to evaluate the effects of ECP and EFS on their growth performance, antioxidant capacity, and inflammatory responses. The results revealed significantly higher final weights and specific growth rates in both experimental groups than the control (p < 0.05). The proximate chemical compositions of sea cucumber were less affected by the diets (p > 0.05). Compared with the control group, significantly elevated levels of digestive enzymes, antioxidants, and lysozyme, together with lower malondialdehyde levels, were recorded in the experimental groups (p < 0.05). ECP appeared to exhibit greater potency than EFS in enhancing growth performance and antioxidant capacity. Similar trends were observed in the mRNA expression of SOD, CAT, and inflammation-related genes across the groups. In a nutshell, both ECP and EFS supplemented in a low-fishmeal and low-soybean meal diet could effectively promote the growth and health of A. japonicus, with ECP showing a superior effect over EFS. These findings suggest that enzymatic hydrolysate demonstrates potential as a viable alternative to traditional fishmeal and soybean meal in diets for sustainable sea cucumber aquaculture. Further investigations are warranted to reveal its underlying mechanism. Full article

The aquafeed industry increasingly relies on using sustainable and appropriate protein sources to ensure the long-term sustainability and financial viability of intensive aquaculture. Yeast has emerged as a viable substitute protein source in the aquaculture sector due to its potential as a nutritional supplement. A substantial body of evidence exists to suggest that yeast has the potential to act as an effective immune-stimulating agent for a range of aquaculture fish species. Furthermore, the incorporation of yeast supplements and feed additives has the potential to bolster disease prevention, development, and production within the aquaculture sector. Except for methionine, lysine, arginine, and phenylalanine, which are typically the limiting essential amino acids in various fish species, the various yeast species exhibit amino acid profiles that are advantageous when compared to fishmeal. The present review considers the potential nutritional suitability of several yeast species for fish, with particular attention to the various applications of yeast in aquaculture nutrition. The findings of this study indicate that the inclusion of yeast in the diet resulted in the most favorable outcomes, with improvements observed in the overall health, growth performance, and nutritional condition of the fish. Digestibility, a key factor in sustainable feed development, is discussed in special detail. Additionally, this review addresses the utilization of yeast as an immunostimulating agent for fish and its digestion in fish. Furthermore, the research emphasizes the necessity of large-scale production of yeast as a substitute for fishmeal in aquaculture. Full article

The increasing frequency and duration of marine heatwaves (MHWs) due to climate change pose severe threats to aquaculture, causing drastic physiological and growth impairments in farmed fish, undermining their resilience against additional environmental pressures. To ensure sustainable production that meets the global seafood demand and animal welfare standards, cost-effective and eco-friendly strategies are urgently needed. This study explored the efficacy of the red macroalga Asparagopsis taxiformis on juvenile white seabream Diplodus sargus reared under optimal conditions and upon exposure to a MHW. Fish were fed with four experimental diets (0%, 1.5%, 3% or 6% of dried powdered A. taxiformis) for a prophylactic period of 30 days (T30) and subsequently exposed to a Mediterranean category II MHW for 15 days (T53). Biometric data and samples were collected at T30, T53 and T61 (8 days post-MHW recovery), to assess performance indicators, biomarker responses and histopathological alterations. Results showed that A. taxiformis supplementation improved catalase and glutathione S-transferase activities and reduced lipid peroxidation promoted by the MHW, particularly in fish biofortified with 1.5% inclusion level. No histopathological alterations were observed after 30 days. Additionally, fish biofortified with 1.5% A. taxiformis exhibited increased citrate synthase activity and fish supplemented with 1.5% and 3% showed improved digestive enzyme activities (e.g., pepsin and trypsin activities). Overall, the present findings pointed to 1.5% inclusion as the optimal dosage for aquafeeds biofortification with A. taxiformis, and confirmed that this seaweed species is a promising cost-effective ingredient with functional properties and great potential for usage in a climate-smart context. Full article

The aim of this research is to explore the potential effects of two microalgae-based additives included in finishing feeds on the quality and shelf-life of seabream fillets. In a 41-day feeding trial, seabream specimens were fed with experimental aquafeeds containing 10% of the bioactive supplements. These additives consisted of a blend of Nannochloropsis gaditana and Arthrospira platensis biomass, which was utilized as either raw (LB-CB) or enzymatically hydrolyzed (LB-CBplus). A control group received a microalgae-free diet. The results showed that the functional aquafeeds improved the nutritional profile of seabream fillets, increasing protein and PUFA-n3 contents while reducing the atherogenic index, especially for the LB-CBplus treatment. LB-CBplus also enhanced the texture parameters (hardness and chewiness) of fillets during the initial 5 days under cold storage. Regarding skin pigmentation, fillets showed increased greenish and yellowish coloration compared to control fish, mostly attributed to the inclusion of crude algal biomass (LB-CB). Moreover, diets enriched with microalgae additives effectively delayed muscle lipid oxidation processes under refrigeration for up to 12 days, with LB-CBplus exhibiting higher antioxidant effects. These findings highlight the potential of microalgae-based additives to enhance both the nutritional and organoleptic quality of seabream fillets. Full article

The present study aims to evaluate methanol-extracted cottonseed meal (CSM) as a potential replacement for fishmeal (FM) in aquafeeds for juvenile cobia Rachycentron canadum. Five isonitrogenous (41% crude protein) and isolipidic (11% crude lipid) diets were formulated with 0 (i.e., the full fishmeal diet, as Control), 25%, 50%, 75% and 100% of the dietary protein from FM replaced by methanol-extracted CSM with L-lysine (L-Lys) and DL-methionine (DL-Met) and supplemented to the established requirement levels for cobia. Diets were fed to triplicate groups of juvenile fish with an average initial weight (±SEM) of 11.35 ± 0.23 g/fish for 9 weeks. Percent weight gain (WG), feed efficiency (FE) and protein efficiency ratio (PER) of fish fed diets with 25% and 50% of FM protein replaced by methanol-extracted CSM were higher or comparable to those of fish fed the Control diet. Those responses were gradually reduced with increasing levels of CSM substitution, resulting in significant (p < 0.05) negative linear trends. Condition factor (CF) and hepatosomatic index (HSI) values significantly decreased with increasing dietary CSM inclusion, as did whole-body protein and lipid composition. Activities of superoxide dismutase (SOD) of fish fed CSM diets were not significantly different compared to that of fish fed the Control diet. The glutathione peroxidase (GSH-Px) and malonaldehyde (MDA) levels, as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities from fish fed diets with 50% or greater of CSM were lower than those of fish fed the Control and CSM25 diets. These results indicated that the inclusion of CSM did not induce any apparent stress on juvenile cobia. Additionally, methanol-extracted CSM with Lys and Met supplementation was able to replace up to 20~30% of crude protein provided by FM in the diet of cobia without drastically affecting the growth performance or body composition. Full article