Aquaculture Nutrition最新文献

To meet the growing market demand for high-quality red swamp crayfish (Procambarus clarkii), nutritional strategies are needed to improve both health and visual traits. The microalga Dunaliella salina, renowned for its rich natural β-carotene content, presents a promising solution. This study investigated the effects of dietary supplementation with D. salina powder at five graded levels (0%, 0.34%, 0.67%, 1.34%, and 2.00%) on juvenile crayfish over a 60-day feeding trial. Results demonstrated that weight gain rate (WGR) and specific growth rate (SGR) were highest in the 2.00% supplementation group. Notably, a low inclusion level of 0.34% significantly promoted ovarian development, as evidenced by the highest gonadosomatic index (GSI) and digestive enzyme activities. Antioxidant capacity (AOC, total superoxide dismutase [T-SOD], total AOC [T-AOC]) and nonspecific immunity (alkaline phosphatase [AKP]) were maximally enhanced at 0.67% inclusion. Most importantly, dietary D. salina was efficiently converted to astaxanthin and deposited in tissues, with carapaces and ovaries coloration parameters showing a strong, dose-dependent correlation with carotenoid accumulation. Regression analysis identified an optimal inclusion range of 1.23%-1.53% for maximizing carotenoid deposition, immune function, and AOC. Furthermore, the 2.00% supplementation group exhibited the highest tolerance to air exposure stress. Our findings provide definitive, data-driven insights for the precise application of D. salina in functional crayfish feeds, facilitating the industry's transition from quantity-focused production to quality- and value-driven aquaculture.

The aim of this study was to investigate the effects of an effective microorganism (EM)-based microbial inoculum on the growth and expression of related genes in 1-year-old healthy Megalobrama amblycephala. The bacterial strains included Lactobacillus plantarum, Lactobacillus fermentum, Enterococcus faecium, Bacillus velezensis, Paenibacillus polymyxa and Lactococcus sp. The fish were randomly divided into five groups: one group was fed a basal diet (control group), and the other groups were provided feed containing EMs at levels of 5, 10, 20 or 40 g/kg. The growth performance, gastrointestinal digestive enzyme activity and expression of the growth hormone (GH), GH receptor A (GHRA), GH receptor B (GHRB) and insulin-like growth factor-1 (IGF-1) genes in the liver of M. amblycephala after 60 days of outdoor cage culture were analysed. The weight gain rate for M. amblycephala significantly increased when EM was added to the feed, and the 10 g/kg EM group had the greatest weight gain, which was 7.34% higher than that of the control group; this group also presented the highest intestinal protease and lipase activities. Regarding hormone levels, GH, GHRA, GHRB and IGF-1 expression levels were highest in the 10 g/kg EM group. Additionally, EM addition significantly improved lipoprotein metabolism in the liver, resulting in a decrease in low-density lipoprotein levels and an increase in high-density lipoprotein levels. The results of this study suggest that EM supplementation in feed improves the growth performance of M. amblycephala, reduces the risk of fatty liver and affects the expression of growth genes.

This study aimed to determine the effect of replacing fish meal (FM), soybean meal (SBM), and corn protein concentrate (CPC) in an equal ratio with corn fermented protein (CFP) on Pacific white shrimp, Litopenaeus vannamei growth, feed utilization efficiency, hemolymph parameters, and physiological gene expression. A green water recirculation system was employed with a stocking density of 30 shrimp per tank (~35 shrimp/m²) and an initial weight of 0.216 ± 0.007 g (mean ± standard deviation). Six experimental diets were investigated over 8 weeks. The primary protein sources in the basal diet were systematically replaced (0% – 25% diet) with CFP. No significant changes in shrimp growth indicators were found between shrimp reared on the various diets (p  > 0.05). We found few significant differences in feed utilization efficiency (p  > 0.05), but especially for feed conversion ratio (FCR; p = 0.372) shifts in net phosphorus retention (PR; p  < 0.001) were significant. Physiological gene expression analysis revealed no signs of gut inflammation or digestive enzyme disorders (p  > 0.05). At the same time, the hemolymph index exhibited similar patterns with no statistically significant outcome (p  > 0.05). The results showed that, under a setting with natural productivity, different replacement levels did not impair the growth response, feed consumption, physiological gene expression, and hemolymph indicators of Pacific white shrimp when appropriately balanced with other protein sources. The results demonstrated the feasibility of replacing the primary protein source with CFP in practical feed applications. Overall, using CFP in shrimp feed formulation resulted in a good growth rate with no adverse effects.

This study evaluated the anthelmintic efficacy of rosemary oil delivered as a nanoemulsion compared with regular rosemary oil against the monogenean parasite Zeuxapta seriolae in yellowtail kingfish (YTK; Seriola lalandi). A 20-day feeding trial tested three dietary treatments: two levels of regular rosemary oil (providing 0.85 and 1.7 g cineole·kg⁻¹ feed) and a rosemary-oil nanoemulsion (providing 0.85 g cineole·kg⁻¹ feed), against a control diet without rosemary oil. Juvenile fish (293 ± 5 g) were pre-exposed to Z. seriolae oncomiracidia before the trial, resulting in an initial mean parasite abundance of 97 ± 4 per fish. At trial completion, plasma cineole concentrations were highest in fish receiving the high-dose regular rosemary oil diet, followed by the nanoemulsion diet, and then the low-dose regular rosemary oil. These plasma levels closely matched treatment efficacy: fish fed the high-dose diet exhibited the lowest mean abundance of Z. seriolae, followed by those receiving the nanoemulsion and low-dose diets. A similar pattern was observed for juvenile parasite recruitment. Across parasite developmental stages, all rosemary-oil treatments significantly reduced the proportion of juvenile Z. seriolae relative to the control. Growth performance and feed intake did not differ among treatments. Plasma biochemistry remained unchanged, and no histopathological alterations were detected in liver or kidney tissues. Overall, these findings demonstrate that dietary rosemary oil effectively transfers cineole into the blood of YTK and reduces Z. seriolae infection and that application of the rosemary oil in a nanoemulsion further increases cineole uptake.

The aquaculture sector plays a key role in ensuring food and nutritional security as well as fostering economic growth in sub-Saharan Africa (SSA). However, as the sector continues to grow, its future faces economic, environmental, and sustainability challenges. At the core of these challenges are the substantial nutritional and health requirements of the farmed fishes that are cultured semi-intensively and intensively. Nutrient-balanced feed resources like fish meal and soybean are highly indispensable in most aquaculture production systems in SSA. However, these ingredients are limited, expensive, and are also in direct competition with farmed terrestrial animals and humans. Additionally, frequent disease outbreaks, especially due to the impact of climate change, pose viability challenges that are traditionally controlled using chemotherapeutics. But their indiscriminate usage has led to the occurrence of resistant microbes in the environment further adding to the challenges. Functional ingredients (FIs), derived from plants and microbial sources, are emerging as viable options to address both the nutritional and health issues of farmed fish. FIs contribute to fish health, growth performance, and resilience to disease and stress not only through their antioxidant, immunomodulatory, and antimicrobial properties but also by their nutritional benefits. The incorporation of these ingredients, into fish feeds can greatly reduce production costs, ecological footprint, and reliance on finite marine resources and synthetic drugs. However, FIs, with a few exceptions, have not been widely adopted in the aquafeed industry. This review aims to critically examine the reasons behind their limited adoption in the aquafeed industry, identifying key challenges and research gaps that hinder their widespread application. Additionally, it explores and evaluates the potential role of FIs in formulating cost-effective and functional aquafeeds with a low ecological footprint. A particular focus is given to their role in enhancing aquaculture productivity in the SSA region, highlighting opportunities for sustainable growth and the need for further research to optimize their efficacy and commercial viability.

This study evaluated the comparative efficacy of synbiotics, probiotics, prebiotics, and antibiotics in enhancing the growth performance, intestinal health, hepatic regeneration, and immune response of stinging catfish (Heteropneustes fossilis). Over a 45-day experimental period, fingerlings were fed diets supplemented with antibiotics (Erisen-Vet or Renamycin), probiotics (Everfresh-Pro), prebiotics (onion powder), or a synbiotic combination (Everfresh-Pro + onion powder). The results demonstrated that the T_Syn group consistently outperformed all other treatments. Quantitatively, the synbiotic group achieved the highest final weight (15.75 ± 1.77 g) and weight gain (11.75 ± 1.25 g) compared to the control (T_Con) (4.01 ± 0.44 g weight gain). The specific growth rate (SGR) was significantly higher in T_Syn (3.05% day⁻¹) than in antibiotic groups, while the feed conversion ratio (FCR) was optimized at 0.98 in T_Syn versus 1.35 in T_Con. Intestinal histomorphology showed marked improvements in the T_Syn group, with villus length reaching 368.54 ± 21.52 µm and villus area at 85.93 ± 5.91 mm², significantly exceeding both antibiotic and control values (p < 0.01). Immune response indicators were similarly enhanced; the total white blood cell (WBC) count in T_Syn rose to 11.26 × 10³/mm³ by day 45, compared to 8.45 × 10³/mm³ in the control. Furthermore, mucosal immunity was bolstered in the synbiotic group, which exhibited the highest goblet cell count (84.00 ± 3.00) and widest lamina propria (7.04 ± 0.81 µm). In conclusion, synbiotics not only promote superior growth and feed efficiency but also significantly enhance gut health, hepatic regeneration, and immune profiles. These findings provide strong evidence that synbiotics are a superior, sustainable alternative to antibiotics for the intensive culture of stinging catfish.

The increase and rapid population growth and higher demand for fish are driving the aquaculture industry to rapid expansion. One of the main challenges in aquaculture is to ensure sustainable feeds for fish in different aquaculture systems. Historically, aquafeed ingredients were fishmeal and fish oil, but the increase in price and the decrease in availability have resulted in the utilization of some plant-based aquafeed. One of the most utilized plant-based aquafeed and alternative protein sources is soybean meal (SBM). However, the use of aquafeed high in plant protein affects the growth performance, and the production of SBMs requires arable land and freshwater that could be used for crops for human consumption. The substitute aquafeed must possess valuable content, including protein with essential amino acids and lipids with omega 3 fatty acids, and must be palatable and digestible, and it should have low levels of insoluble carbohydrates, fiber, and heavy metals, as these factors can impact fish growth and health. Focusing on microalgae as sustainable alternative has gained interest because microalgae naturally exist in aquatic food chains, with appropriate biochemical composition that could be suitable for lipid substitute in feed as well as fish oil, rich in proteins, carbohydrates, pigments, and other antioxidants. Microalgae, with this balanced composition and high biomass productivity, are considered as a potential aquafeed that can replace conventional ingredients. In this review, we describe how microalgae inclusion in aquafeed or as alternative to conventional sources is conduct to improve sustainability and quality of aquafeeds.

Plant-derived extracts offer a promising alternative to synthetic additives in fish feed, with the aim of enhancing growth, health, and sustainable production. The present study aimed to evaluate the effect of the hydroalcoholic extract of dietary Chaste tree, Vitex agnus-castus (VAC), on growth performance, feed utilization, digestive enzymes, hematological, serum biochemical parameters, intestinal histomorphometry, and flesh composition and quality of Nile tilapia, Oreochromis niloticus. A total of 160 Nile tilapia fingerlings were allocated in five equal treatments and fed increasing levels of VAC extract (0, 5, 10, 15, and 20 g/kg of diet) and referred as control, VAC₅, VAC₁₀, VAC₁₅, and VAC₂₀, respectively, for 8 weeks. Fish in the VAC₅ group achieved the highest growth performance, digestive enzyme activities, and significantly improved feed conversion ratio (FCR) and protein efficiency ratio (PER). The predicted maximum VAC level supplementation was 9.81 g kg^–1 diet as determined by quadratic regression based on growth and feed utilization. The hematological parameters increased significantly in the VAC_{5 and 10} groups. Liver function enzymes, glucose (GLU), triglycerides (TGs), and creatinine were significantly decreased, while total protein (TP) and albumin (ALB) were significantly increased in fish fed VAC₅ and VAC₁₀ diets. However, total cholesterol (TCH) was significantly increased with VAC supplementation on a level-dependent basis. Histometric investigation of the intestinal tract revealed a significant improvement in muscular and submucosal thickness, villi length, and width. The chemical composition of the muscle revealed an improvement in protein and dry matter in the VAC₅ group, with decreased water loss during storage, dripping, and freezing. In conclusion, VAC extract can be used as a feed additive in the Nile tilapia diet at levels of 5–10 g kg^–1 diet with a positive response in growth, physiological response, and histological architecture.

This study evaluated the feasibility of replacing soybean lecithin (SBL) with lysophospholipids (LYLs) in the diet of Pacific white shrimp, Litopenaeus vannamei. Five isonitrogenous diets were formulated as the control diet with 15 g/kg soybean oil and 15 g/kg SBL inclusion (LYL-0), three SBL-substituted diets with 1/3, 2/3, and 3/3 of SBL substituted with the same amounts of LYL (LYL-0.5, LYL-1, and LYL-1.5), and a low-lipid diet (LYL-L) with 5 g/kg soybean oil and 15 g/kg LYL inclusion. Then, shrimp (1.6 ± 0.1 g) were fed with the above diets for 8 weeks. The LYL-1.5 group presented significantly higher weight gain (WG) than the control (p < 0.05), but no significant difference was observed in WG and feed conversion ratio (FCR) between the control and LYL-L group, or between the LYL-L and LYL-1.5 group (p > 0.05). Whole-body lipid levels were found to be substantially increased in the LYL-1 and LYL-1.5 groups compared to the control, while hepatopancreatic lipid content and lipid droplet area (Oil Red O stain) were significantly lower in the LYL-1, LYL-1.5, and LYL-L groups (p < 0.05). Serum high-density lipoprotein cholesterol (HDL-C), lipoprotein lipase (LPL), hepatic lipase activities, and the apparent digestibility of crude lipid were significantly increased in the LYL-1 and LYL-1.5 groups (p < 0.05). In contrast, serum triglyceride (TG) and total cholesterol (TC) levels were significantly decreased in the LYL-1.5 and LYL-L groups (p < 0.05). In summary, under the present conditions, the complete replacement of SBL with LYLs improved growth performance and lipid metabolism and enabled a 10 g/kg reduction in dietary lipid level for Pacific white shrimp.

Rearing variables, such as water temperature and dietary composition, can significantly affect gut transit time (GTT) in cultured Atlantic salmon (Salmo salar). These influences can accelerate the transit of digesta, leading to reduced nutrient digestibility and uptake, whilst impacting feed intake, appetite and gut evacuation, which collectively may result in inefficient feed utilisation in commercial aquaculture. To address these issues, manipulating the physical properties of the diet, specifically pellet and raw material particle size, may present a solution via the modulation of the GTT in fish. This study aimed to evaluate the GTT of 360 pre-smolt Atlantic salmon (120.58 ± 0.25 g) fed one of six dietary treatments varying in raw material particle size (fine: 0–250 μm, medium: 250–500 μm or coarse: 500 μm–1000 μm) and subsequent pellet size (3 mm or 5 mm) using a factorial design. GTT was quantified by assessing the relative distribution of an inert feed marker (ballotini® beads), incorporated in the feed, in three defined digestive tract regions: the stomach (ST), mid-intestine (MI) and distal intestine (DI). It was found that the larger pellet size resulted in faster transit of digesta, but the relationship between raw material particle size (fine, medium or coarse) and transit rate was highly variable. However, the time taken for 50% evacuation of the digesta present in the GI tract is modulated by both pellet and raw material particle size. The insights gained from this research could guide the development of commercial diets designed to mitigate the negative impacts of an accelerated gut transit. Consequently, this approach has the potential to enhance feed efficiency from both nutritional and economic perspectives and reduce the environmental impact caused by excessive nitrogenous waste production in aquaculture.