Effects of dietary Astragalus polysaccharides on growth, health and resistance to Vibrio harveyi of Lates calcarifer

Effects of dietary ginger (Zingiber officinale) polysaccharide on the growth, antioxidant, immunity response, intestinal microbiota, and disease resistance to Aeromonas hydrophila in crucian carp (Carassius auratus)

Ginger polysaccharides (GP) promote growth and development in fish. However, the effects of GP on crucian carp remain unclear. The present study investigated the effects of GP on the growth performance, immunity, intestinal microbiota, and disease resistance in crucian carp. Four treatment groups were established with different concentrations of GP (0.1 %, 0.2 %, 0.4 %, and 0.8 %). GP was not added as the control group, and the feeding period lasted for 56 d, followed by a 96-h anti-infection treatment using Aeromonas hydrophila. The results showed that dietary GP significantly improved growth performance, especially in the 0.4 % GP group. Furthermore, GP administration notably increased serum lysozyme (LMZ) activity, digestive enzyme performance, and antioxidant capacity of crucian carp. Moreover, dietary inclusion of GP up-regulated the expression of tumour necrosis factor-α (TNF-α), interleukin-8 (IL-8), interferon-γ (IFN-γ), and nuclear factor kappa-B (NF-κB) genes while down-regulating IL-10 and transforming growth factor-β (TGF-β) gene expressions, thus promoting liver health in crucian carp. Additionally, incorporating GP into the diet regulated both the diversity and composition of the intestinal microbiota in crucian carp, explicitly enhancing the relative abundance of beneficial bacteria, such as Fusobacteriota and Firmicutes. Therefore, GP reduces the mortality of crucian carp infected with A. hydrophila. In conclusion, this study provides novel insights into the application of dietary GP in cultured fish and evaluates the value of traditional Chinese medicinal polysaccharides against pathogenic bacteria.

Regulatory effects of Astragalus membranaceus polysaccharides on lipid metabolism disorders induced by a high-fat diet in spotted sea bass (Lateolabrax maculatus)

This study evaluated the regulatory effects of Astragalus membranaceus polysaccharides (AMP) on lipid metabolism disorders induced by a high-fat diet (HFD) in spotted sea bass (Lateolabrax maculatus). Compared with the normal diets (10 % lipids), diets containing 15 % lipid levels were used as the high-fat diet (HFD). Three levels of the AMP (0.06 %, 0.08 %, 0.10 %) were added in the HFD and used as experimental diets. A total of 375 spotted sea bass (average weight 3.00 ± 0.01 g) were divided into 15 tanks and deemed as 5 groups, with each tank containing 25 fish. Fish in each group were fed with different diets for 56 days. After feeding, the HFD induced lipid metabolism disorders in fish, as evidenced by elevated serum lipids, malonaldehyde levels, and more severe liver damage. The AMP alleviated the HFD-induced liver damage, as evidenced by the reduced severity of liver histological lesions and malonaldehyde levels. The low-density lipoprotein cholesterol was reduced, and the expression of FAS and PPAR-α were down and up-regulated, respectively. However, the AMP had a limited ability to affect the serum lipids and abdominal fat percentage. These results reveal the potential of the AMP used in aquaculture to regulate lipid metabolism disorders induced by the HFD.

Astragalus polysaccharide: implication for intestinal barrier, anti-inflammation, and animal production

Intestine is responsible for nutrients absorption and plays a key role in defending against various dietary allergens, antigens, toxins, and pathogens. Accumulating evidence reported a critical role of intestine in maintaining animal and human health. Since the use of antibiotics as growth promoters in animal feed has been restricted in many countries, alternatives to antibiotics have been globally investigated, and polysaccharides are considered as environmentally friendly and promising alternatives to improve intestinal health, which has become a research hotspot due to its antibiotic substitution effect. Astragalus polysaccharide (APS), a biological macromolecule, is extracted from astragalus and has been reported to exhibit complex biological activities involved in intestinal barrier integrity maintenance, intestinal microbiota regulation, short-chain fatty acids (SCFAs) production, and immune response regulation, which are critical for intestine health. The biological activity of APS is related to its chemical structure. In this review, we outlined the source and structure of APS, highlighted recent findings on the regulation of APS on physical barrier, biochemical barrier, immunological barrier, and immune response as well as the latest progress of APS as an antibiotic substitute in animal production. We hope this review could provide scientific basis and new insights for the application of APS in nutrition, clinical medicine and health by understanding particular effects of APS on intestine health, anti-inflammation, and animal production.

Dietary Black Soldier Fly (Hermetia illucens)-Dipterose-BSF-Enhanced Zebrafish Innate Immunity Gene Expression and Resistance to Edwardsiella tarda Infection

Dietary management using immunostimulants to protect fish health and prevent bacterial infection is widely practiced. Many insect species possess various bioactive substances that can improve animal health. We previously identified several bioactive polysaccharides derived from insects, including dipterose-BSF from black soldier fly (Hermetia illucens) larvae; this can stimulate innate immunity in mammalian macrophage RAW264.7 cells. However, the effect of dietary dipterose-BSF on the immune system of teleosts remains unclear. Here, we analyzed the immune status of zebrafish (Danio rerio) after 14 days of dietary inclusion of dipterose-BSF (0.01, 0.1, and 1 µg/g), followed by an immersion challenge using Edwardsiella tarda. To identify changes in the transcriptional profile induced by dipterose-BSF, we performed RNA-sequencing analyses of the liver and intestine. Differentially expressed genes were investigated, with both organs showing several upregulated genes, dominated by nuclear factor and tumor necrosis factor family genes. Gene Ontology analysis revealed several terms were significantly higher in the experimental group compared with the control group. Challenge tests suggested that dietary dipterose-BSF had some positive effects on disease resistance in fish, but these effects were not pronounced.

Effects of Shrimp Shell-Derived Chitosan on Growth, Immunity, Intestinal Morphology, and Gene Expression of Nile Tilapia (Oreochromis niloticus) Reared in a Biofloc System

Chitosan (CH) shows great potential as an immunostimulatory feed additive in aquaculture. This study evaluates the effects of varying dietary CH levels on the growth, immunity, intestinal morphology, and antioxidant status of Nile tilapia (Oreochromis niloticus) reared in a biofloc system. Tilapia fingerlings (mean weight 13.54 ± 0.05 g) were fed diets supplemented with 0 (CH0), 5 (CH5), 10 (CH10), 20 (CH20), and 40 (CH40) mL·kg-1 of CH for 8 weeks. Parameters were assessed after 4 and 8 weeks. Their final weight was not affected by CH supplementation, but CH at 10 mL·kg-1 significantly improved weight gain (WG) and specific growth rate (SGR) compared to the control (p < 0.05) at 8 weeks. Skin mucus lysozyme and peroxidase activities were lower in the chitosan-treated groups at weeks 4 and 8. Intestinal villi length and width were enhanced by 10 and 20 mL·kg-1 CH compared to the control. However, 40 mL·kg-1 CH caused detrimental impacts on the villi and muscular layer. CH supplementation, especially 5-10 mL·kg-1, increased liver and intestinal expressions of interleukin 1 (IL-1), interleukin 8 (IL-8), LPS-binding protein (LBP), glutathione reductase (GSR), glutathione peroxidase (GPX), and glutathione S-transferase (GST-α) compared to the control group. Overall, dietary CH at 10 mL·kg-1 can effectively promote growth, intestinal morphology, innate immunity, and antioxidant capacity in Nile tilapia fingerlings reared in biofloc systems.

Dietary Supplementation of Astragalus membranaceus Extract Affects Growth Performance, Antioxidant Capacity, Immune Response, and Energy Metabolism of Largemouth Bass (Micropterus salmoides)

The present study investigated the effects of Astragalus membranaceus extract (AME) on growth performance, immune response, and energy metabolism of juvenile largemouth bass (Micropterus salmoides). Seven diets containing 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6% AME (Con, AME0.1, AME0.2, AME0.3, AME0.4, AME0.5, and AME0.6 groups) were formulated and fed to M. salmoides for 8 weeks. Final body weight (FBW), feed intake (FI), weight gain (WG), and specific growth rate (SGR) were all significantly higher in AME0.4 group than in Con group (P < 0.05). Feed conversion rate (FCR) was significantly improved in AME0.5 group compared with Con group (P < 0.05). Whole-body crude protein contents were significantly increased in AME0.2 group (P < 0.05). Whole-body crude lipid contents were significantly lower in AME0.2 and AME0.3 groups, while muscle lipid was upregulated by dietary AME (P < 0.05). Hepatic malondialdehyde (MDA) contents were significantly lowered in AME0.3 and AME0.4 groups, and catalase (CAT) activities were significantly increased in AME0.1 and AME0.2 groups (P < 0.05). Plasma aspartate aminotransferase (AST) level was significantly lowered in AME0.5, and AME0.6 groups, and alanine aminotransferase (ALT) level was lowered in AME0.5 groups (P < 0.05). Plasma triglyceride was declined in AME0.6 group, and glucose was decreased by 0.3%-0.5% AME (P < 0.05). Significantly higher hepatocyte diameter, lamina propria width, and submucosal layer thickness were recorded in AME0.6 groups, while the longest villi height was obtained in AME0.2 and AME0.3 groups (P < 0.05). The mRNA expression levels of insulin-like growth factor 1 (igf1) revealed the growth-promoting effect of AME. The anti-inflammatory and antiapoptotic effects of AME were demonstrated by transcription levels of interleukin 8 (il-8), tumor necrosis factor-alpha (tnf-a), caspase, B-cell lymphoma-xl (Bcl-xl), bcl-2 associated x (Bax), and bcl-2-associated death protein (Bad). The transcription levels of lipid metabolism and gluconeogenesis related genes, including acetyl-CoA carboxylase alpha (acc1), fatty acid synthase (fasn), fatty acid binding protein 1 (fabp1), phosphoenolpyruvate carboxykinase 2 (pepck2), and glucose-6-phosphatase catalytic subunit 1a (g6pc), were reduced by AME treatment, while the levels of glycolysis-related genes, including glucokinase (gck) and pyruvate kinase (pk), were the highest in AME0.2 and AME0.3 groups (P < 0.05). According to polynomial regression analysis of SGR, WG, FCR, whole-body crude lipid, MDA, and ALT, the optimal AME supplementation level was estimated to be 0.320%-0.429% of the diet. These results provided insights into the roles of AME in regulating immunity and metabolism, which highly indicated its potential as immunostimulants and metabolic regulators in diverse aquatic animals.

Quercetin alleviates the toxicity of difenoconazole to the respiratory system of carp by reducing ROS accumulation and maintaining mitochondrial dynamic balance

Difenoconazole (DFZ) is a fungicidal pesticide extensively employed for the management of fungal diseases in fruits, vegetables, and cereal crops. However, its potential environmental impact cannot be ignored, as DFZ accumulation is able to lead to aquatic environment pollution and harm to non-target organisms. Quercetin (QUE), a flavonoid abundant in fruits and vegetables, possesses antioxidant and anti-inflammatory properties. In this article, carp were exposed to 400 mg/kg QUE and/or 0.3906 mg/L DFZ for 30 d to investigate the effect of QUE on DFZ-induced respiratory toxicity in carp. Research shows that DFZ exposure increases reactive oxygen species (ROS) production in the carp's respiratory system, leading to oxidative stress, inflammation, and damage to gill tissue and tight junction proteins. Further research demonstrates that DFZ induces mitochondrial dynamic imbalance and gill cell apoptosis. Notably, QUE treatment significantly reduces ROS levels, alleviates oxidative stress and inflammation, and mitigates mitochondrial dynamics imbalance and mitochondrial apoptosis. This study emphasizes the profound mechanism of DFZ toxicity to the respiratory system of common carp and the beneficial role of QUE in mitigating DFZ toxicity. These findings contribute to a better understanding of pesticide risk assessment in aquatic systems and provide new insights into strategies to reduce their toxicity.

Soluble non-starch polysaccharides in fish feed: implications for fish metabolism

Because of their unique glycosidic bond structure, non-starch polysaccharides (NSP) are difficult for the stomach to break down. NSP can be classified as insoluble NSP (iNSP, fiber, lignin, etc.) and soluble NSP (sNSP, oligosaccharides, β-glucan, pectin, fermentable fiber, inulin, plant-derived polysaccharides, etc.). sNSP is viscous, fermentable, and soluble. Gut microbiota may catabolize sNSP, which can then control fish lipid, glucose, and protein metabolism and impact development rates. This review examined the most recent studies on the impacts of various forms of sNSP on the nutritional metabolism of various fish in order to comprehend the effects of sNSP on fish. According to certain investigations, sNSP can enhance fish development, boost the activity of digestive enzymes, reduce blood sugar and cholesterol, enhance the colonization of good gut flora, and modify fish nutrition metabolism. In-depth research on the mechanism of action is also lacking in most studies on the effects of sNSP on fish metabolism. It is necessary to have a deeper comprehension of the underlying processes by which sNSP induce host metabolism. This is crucial to address the main issue of the sensible use of carbohydrates in fish feed.

The Combination of β-Glucan and Astragalus Polysaccharide Effectively Resists Nocardia seriolae Infection in Largemouth Bass (Micropterus salmoides)

Effectively treating and preventing outbreaks is crucial for improving the economic benefits of aquaculture. Therefore, utilizing immunostimulants, either alone or in combination, is regarded as a promising strategy. In this study, β-glucan + APS (200 mg/kg + 200 mg/kg), β-glucan (200 mg/kg), APS (200 mg/kg), enrofloxacin (15 mg/kg), and sulfadiazine (15 mg/kg) were added to feed to assess the effects against Nocardia seriolae infection in largemouth bass (Micropterus salmoides) within 14 days. The survival rates did not differ between the enrofloxacin group and the β-glucan + APS group, but both were significantly higher than that of the control group. Additionally, the enrofloxacin group and the β-glucan + APS group exhibited the lowest bacterial loads and tissue damage. Importantly, the β-glucan + APS treatment significantly improved serum enzyme activities (total superoxide dismutase, lysozyme, total protein) and the expression of immune genes (IL-1β, TNF-α, IFN-γ, IgM) compared to the other treatment groups. The enrofloxacin group showed similar efficacy to the β-glucan + APS group in combating N. seriolae infection, but N. seriolae in the enrofloxacin group developed drug resistance. In summary, the combined use of β-glucan and APS is a promising strategy for treating bacterial diseases, thereby contributing to the promotion of sustainable aquaculture development.

Dietary Astragalus polysaccharides improve the growth and innate immune response of giant freshwater prawn Macrobrachium rosenbergii: Insights from the brain-gut axis

Supplementation with Astragalus polysaccharides (APS) has beneficial effects on aquatic animals. Herein, we aimed to investigate the effects of different doses of APS on the growth, innate immune response, and brain-gut axis of Macrobrachium rosenbergii. The molecular weight and the monosaccharide composition of APS were analyzed. APS were added at concentration of 0 (control), 0.05, 0.10, 0.15, and 0.20 % in practical diets. Growth performance increased significantly under 0.05 to 0.20 % APS, with enhanced lipase and protease activities in intestinal tissues. Prawns receiving APS supplementation had significantly lower amounts of pathogenic intestinal bacteria (Vibrio and Aeromonas) and a markedly different microbial community structure compared with those of the control group. The fecal short chain fatty acid (SCFA) and neurotransmitters γ-aminobutyric acid contents increased in the brains of prawns receiving APS, which was potentially associated with increased Lactobacillus and Bacillus levels. Prawns receiving APS supplementation displayed a significantly enhanced immune function (such as total hemocyte count, total protein concentration, phenoloxidase activity, serum agglutination titer, and lysozyme activity) and improved disease resistance to Vibrio anguillarum compared those in the control group. Thus, dietary APS positively affected the gut-brain axis by altering the microbiota composition, increasing the fecal SCFA content, and enhancing prawn immunity.

Effects of Astragalus membranaceus Polysaccharides on Growth Performance, Physiological and Biochemical Parameters, and Expression of Genes Related to Lipid Metabolism of Spotted Sea Bass, Lateolabrax maculatus

This experiment investigated the effects of Astragalus membranaceus polysaccharides (AMP) on growth, physiological and biochemical parameters, and the expression of lipid metabolism-related genes in spotted sea bass, Lateolabrax maculatus. A total of 450 spotted sea bass (10.44 ± 0.09 g) were divided into six groups and were given diets with different levels of AMP (0, 0.2, 0.4, 0.6, 0.8, and 1.0 g/kg) for 28 days, respectively. Results indicated that dietary intake of AMP significantly improved fish weight gain, specific growth rate, feed conversion, and trypsin activity. Meanwhile, fish fed with AMP manifested significantly higher serum total antioxidant capacity and activity of hepatic superoxide dismutase, catalase, and lysozyme. Lower triglyceride and total cholesterol were noted in fish fed with AMP (P < 0.05). Moreover, hepatic ACC1 and ACC2 were downregulated by dietary intake of AMP, and PPAR-α, CPT1, and HSL were upregulated accordingly (P < 0.05). Parameters with significant difference were analyzed by quadratic regression analysis, and results showed that 0.6881 g/kg of AMP is the optimal dosage for spotted sea bass in size (10.44 ± 0.09 g). In conclusion, dietary intake of AMP can improve the growth, physiological status, and lipid metabolism of spotted sea bass, thereby indicating its promise as a potential dietary supplement.

Lycium barbarum polysaccharides improve lipid metabolism disorders of spotted sea bass Lateolabrax maculatus induced by high lipid diet

This experiment explored the effects of Lycium barbarum polysaccharides (LBP) on lipid metabolism of spotted sea bass Lateolabrax maculatus. Blank and experimental control diets with 100 and 150 g/kg lipid were designed, respectively, and three dosages of LBP (0.75, 1.00, 1.25 g/kg) were supplemented in the experimental control diet. A total 375 of spotted sea bass (19.33 ± 0.15) g were divided into 5 groups, and were given experimental diets for 56 days, respectively. Results showed fish were induced to lipid metabolism disorders with dietary 150 g/kg lipid intake, which manifested in reduced feeding, oxidative stress, elevated serum lipid, and more severe hepatic damage. Dietary LBP improved the lipid metabolism disorders of fish, as indicated by significant enhancements in weight gain, digestion, superoxide dismutase activity, and decreases in malonaldehyde content, and activity of alanine aminotransferase and aspartate aminotransferase. Accordingly, an improvement in the hepatic morphological and expression of lipid metabolism related genes, including FAS, PPAR-α, CPT1 and ATGL, was observed. Nevertheless, no significant variation in serum triglyceride and total cholesterol was observed. Overall, dietary LBP can improve the growth, digestion, antioxidant capacity, and liver health of spotted sea bass, thereby improving the lipid metabolism disorders induced by 150 g/kg dietary lipid intake.

Astragalus polysaccharide improves the growth, meat quality, antioxidant capacity and bacterial resistance of Furong crucian carp (Furong carp♀ × red crucian carp♂)

To evaluate the functional effects of APS (Astragalus polysaccharide) on Furong crucian carp, APS-supplemented diets (0.00 %, 0.05 %, 0.10 % and 0.15 %) were prepared and utilized in feeding experiment. The results showed that the 0.05 % APS group has the highest weight gain rate and specific growth rate, and the lowest feed coefficient rate. In addition, 0.05 % APS supplement could improve muscle elasticity, adhesiveness and chewiness. Moreover, the 0.15 % APS group had the highest spleen-somatic index and the 0.05 % group had the maximum intestinal villus length. 0.05 % and 0.10 % APS addition significantly increased T-AOC and CAT activities while MDA contents decreased in all APS groups. The plasma TNF-α levels in all APS groups significantly increased (P<0.05), and the 0.05 % group showed the highest TNF-α level in spleen. In APS addition groups, the tlr8, lgp2 and mda5 gene expressions were significantly elevated, while xbp1, caspase-2 and caspase-9 expressions decreased in uninfected and A. hydrophila-infected fish. Finally, higher survival rate and slower disease outbreak rate were observed in APS-supplemented groups after being infected by A. hydrophila. In conclusion, Furong crucian carp fed by APS-supplemented diets possesses elevated weight gain rate and specific growth rate, and improved meat quality, immunity and disease resistance.

Integrative mRNA-miRNA interaction analysis associated with the immune response of Strongylocentrotus intermedius to Vibrio harveyi infection

Strongylocentrotus intermedius is one of the most economically valuable sea urchin species in China and has experienced mass mortality owing to outbreaks of bacterial diseases such as black mouth disease. This has caused serious economic losses to the sea urchin farming industry. To investigate the immune response mechanism of S. intermedius with different tube feet colors in response to Vibrio harveyi infection, we examined the different tube feet-colored S. intermedius under V. harveyi challenge and compared their transcriptome and microRNA (miRNA) profiles using RNA-Seq. We obtained 1813 differentially expressed genes (DEGs), 28 DE miRNAs, and 303 DE miRNA-DEG pairs in different tube feet-colored S. intermedius under V. harveyi challenge. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the most significant DEGs were associated with the Notch signaling and phagosome pathways. The target genes of immune-related miRNAs (miR-71, miR-184, miR-193) and genes (CALM1, SPSB4, DMBT, CSRP1) in S. intermedius were predicted and validated. This study provides insight into the molecular mechanisms that regulate genes involved in the immune response of S. intermedius infected with V. harveyi.

Potential role of plant polysaccharides as immunostimulants in aquaculture: a review

Aquaculture is one of the primary food-producing sectors in the world that ensures human nourishment. However, aqua farmers are facing serious problems due to disease out breaks and development of antimicrobial resistance. Until now, chemical or antibiotic based strategies has been applied to control disease related concern in aquaculture. Frequent usage of antibiotics in feed or usage of disinfectant to overcome the disease may end up with negative impacts to the environment and human. Utilization of plant derived polysaccharides has been drastically increased due to their effective roles and could serve as a best replacement for chemical agents and antibiotics. In addition, plant derived compounds and plant extracts was utilized to improve the immunity, intestinal health and growth performance of aquaculturable organisms. In addition, large number of plant-based polysaccharides was utilized as immunostimulants in aquaculture. Hence, this review aims to highlight the multifunctional properties of plant-based polysaccharides in aquaculture. Moreover, advantages and different concentration of plant polysaccharides as a feed additives in aquaculture sector has been discussed herein.

The effect of combined dietary supplementation of herbal additives on carcass traits, meat quality, immunity and cecal microbiota composition in Hungarian white geese

The present study was performed to investigate the effects of dietary supplementation with herbal additives on meat quality, slaughter performance and the cecal microbial community in Hungarian white geese. A total of 60 newborn geese were assigned equally into the control group (CON) and the herbal complex supplemented group (HS). The dietary supplementations consisted of Compound Herbal Additive A (CHAA) including Pulsatilla, Gentian and Rhizoma coptidis, and Compound Herbal Additive B (CHAB) containing Codonopsis pilosula, Atractylodes, Poria cocos and Licorice. The geese in the HS group received a basal diet supplemented with 0.2% CHAA from day 0 to day 42 at the postnatal stage. Then from day 43 to day 70, the geese in HS group were provide a basal diet with 0.15% CHAB. The geese in the CON group were only provided with the basal diet. The results showed that the slaughter rate (SR), half chamber rates (HCR), eviscerated rate (ER) and breast muscle rate (BMR) in the HS group tended to increase slightly compared with the CON group (ns). In addition, the shear force, filtration rate and pH value of breast muscle and thigh muscle in the HS group were slightly enhanced compared to the CON group (ns). Significant increased levels in carbohydrate content, fat content and energy (P < 0.01) and significant decreased levels in cholesterol content (P < 0.01) were observed in the muscle of the HS group. The total amino acid (Glu, Lys, Thr and Asp) content in the muscle increased in HS group than in the CON group (P < 0.01). Dietary herb supplementations significantly increased the levels of IgG in serum (P < 0.05) on day 43 and higher levels of IgM, IgA and IgG (P < 0.01) were also observed in the HS group on day 70. Furthermore, 16S rRNA sequencing results indicated that herbal additives increased the growth of beneficial bacteria and inhibited the proliferation of harmful bacteria in the geese caecum. Altogether, these results offer crucial insights into the potential benefits of incorporating CHAA and CHAB into the diets of Hungarian white goose. The findings indicate that such supplementations could significantly improve meat quality, regulate the immune system and shape the intestinal microbiota composition.

Composition of Three Common Chinese Herbal Medicines and the Influence of Preparation Types on the Bioaccessibility of Trace Elements

The high concentration of trace elements in Chinese herbal medicine (CHM) is an important research topic for quality control. This study investigated the total concentration of trace elements in three herbs used as both medicine and supplementary food, including Astragalus membranaceus, Glycyrrhiza, and Isatidis. Further, the effects of different preparation ways, such as decoct, granule, and oral liquid, on the bioaccessibility of trace elements in CHM were disclosed. Results indicated that the total concentrations of trace elements in these three herbs were lower than the medical standards, but the concentrations of As and Pb in CHMs were higher than the standards for supplementary food. Different preparations ways affect bioaccessibility. Powder and oral liquid show a high bioaccessibility possibly because of the grinding process and the repeated extraction with ethanol. Among the three different CHMs, Isatidis showed higher bioaccessibility of As, which may be related to the sulfur fumigation process of this CHM. The three investigated CHMs were found to be safe as medicine but presented risks as supplementary food. The apparent influence of preparation procedures on the bioaccessibility of trace elements indicated that it is necessary to appropriately regulate preparation processes for CHMs.

Effects of exogenous taurine supplementation on the growth, antioxidant capacity, intestine immunity, and resistance against Streptococcus agalactiae in juvenile golden pompano (Trachinotus ovatus) fed with a low-fishmeal diet

Taurine has various biological functions in fish, playing an essential role in growth, resistance to oxidative stress, and intestine immunity. Here, we evaluated the effects of exogenous taurine added to low-fishmeal diets on the growth, anti-oxidative stress, intestine immunity, and Streptococcus agalactiae resistance in juvenile golden pompano (Trachinotus ovatus). Our study showed that exogenous taurine supplementation of 1.2% (T3 group) greatly enhanced the weight gain rate and specific growth rate (SGR) of juvenile golden pompano, significantly upregulating growth-related factor expression in the brain and liver, as well as the levels of growth-related parameters in the serum. Polynomial regression analysis using SGR estimated the optimal dietary taurine level for golden pompano at 1.18%. Moderate exogenous taurine also increased the muscular thickness and villus length within the intestine, maintained intestinal physical barrier stability, activated the Nrf2/Keap-1/HO-1 signaling pathway, increased intestinal antioxidant enzyme gene expression and antioxidant enzyme activity in the serum, and upregulated immunoglobulin and complement levels in parallel with declining reactive oxygen species (ROS) levels in the serum. Antioxidant factor expression was also upregulated in the intestine. Furthermore, supplementation suppressed NF-κB signaling and intestinal pro-inflammatory cytokine gene expression, increased anti-inflammatory cytokine gene expression, and improved intestine immunity. Finally, taurine supplementation improved the survival rate of golden pompano challenged with S. agalactiae. Overall, our findings provide additional information and support for the rational use of taurine in healthy aquatic animal farming.

Tolerance Assessment of Atractylodes macrocephala Polysaccharide in the Diet of Largemouth Bass (Micropterus salmoides)

Atractylodes macrocephala polysaccharide (AMP) can enhance antioxidant defense and anti-inflammation, as the tolerance levels of AMP in aquaculture is important for additive utilization. However, the tolerance dose of AMP is unknown. We assess the tolerance levels of AMP in juvenile largemouth bass (3.38 ± 0.11 g) by feeding them a 0, 400, 4000, or 8000 mg/kg AMP supplemented diet for 10 weeks. The 400 mg/kg AMP dose increased growth performance. The Nrf2/Keap1 signaling pathway was activated, as indicated by Keap1 and Nrf2 protein levels in the liver. Enhanced activity of antioxidant enzymes (SOD, GPx), together with increased mRNA levels of antioxidant genes (sod, gpx) and decreased accumulation of reactive oxygen species (ROS) and MDA, was found in the liver, implying the antioxidant effect of AMP. Nutrient absorption was enhanced by AMP, as reflected by the increased length of intestinal villi and microvilli. However, 4000 and 8000 mg/kg AMP induced oxidant stress, as indicated by increased plasma ALT and AST content and decreased mRNA levels of antioxidant genes (sod, gpx) in the liver and intestinal tissues. Inflammatory reactions were also induced by high doses of AMP, as reflected by enhanced levels of pro-inflammatory cytokines (tnfα, nfκb) in the liver, intestinal, and kidney tissues and inhibited levels of anti-inflammatory cytokines (tgfβ, iκb). Histological analysis reveals inflammatory cell infiltration and tissue damage. Thus, the safe tolerance margin of AMP supplement for largemouth bass was 400–4000 mg/kg.