Astragalus membranaceus (AM) enhances growth performance and antioxidant stress profiles in bluegill sunfish (Lepomis macrochirus)

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.

Astragalus additive in feed improved serum immune function, rumen fermentation and the microbiota structure of early-weaned lambs

AIM

The purpose of this study was to determine the mechanism of Astragalus activity on the immune function, rumen microbiota structure, and rumen fermentation of early-weaned lambs.

METHODS AND RESULTS

Thirty healthy early-weaned lambs with similar body weights (17.42 ± 2.02 kg) were selected for the feeding experiment. The control group (KB) was fed a basal diet, and the Astragalus group (HQ) was fed 0.3% Astragalus additive on the basis of a basic diet. The formal trial period was 60 days. The results showed that the concentrations of blood immunoglobulin A (IgA) and immunoglobulin M (IgM) in the HQ group were significantly higher than those in the KB group (P < 0.05). Compared with the KB group, the concentrations of acetic acid, butyric acid, and total volatile fatty acids (VFAs) in the HQ group were higher (P < 0.01). The expression levels of the rumen epithelial-related genes MCT1, MCT4, NHE2, and ZO1 in the Astragalus group were significantly higher than those in the KB group (P < 0.05). 16S rRNA analysis showed that at the phylum level, Bacteroidetes in the HQ group significantly increased (P < 0.01); at the genus level, Prevotella (P < 0.01) and Succiniclasticum (P < 0.01) in the HQ group were found at significantly higher abundances than those in the KB group, and the results of microbiota gene and function prediction showed that "energy metabolism," "glycan biosynthesis and metabolic" pathways were significantly enriched in the HQ group (P < 0.05).

CONCLUSION

As a feed additive, Astragalus can improve the immunity of early-weaned lambs, the structure of the rumen microbiota of lambs, and the fermentation capacity of the rumen.

Improving survival, growth, feed utilization, antioxidant status, and fatty acids profile of European seabass, Dicentrarchus labrax, larvae fed silymarin, Silybum marianum, supplemented weaning diet

To sustain normal development, high survival, and rapid growth, marine fish larvae require a diet rich in polyunsaturated fatty acids, which could decrease the risk of reactive oxygen species accumulations. Consequently, a 60-day feeding experiment was conducted to determine the effect of silymarin (SM) supplementation in weaning diets on the growth performance, survival, antioxidant enzyme activities, and fatty acids profile of European seabass (Dicentrarchus labrax) larvae. Four isonitrogenous and isolipidic diets were investigated using SM at levels of 0, 200, 400, and 600 mg kg−1 (SM0.00, SM200, SM400, and SM600, respectively). The findings showed that, in a dose-dependent manner, increasing dietary levels of SM enhanced survival, growth, and feed utilization. In the SM600 group, the weight gain, survival, and feed conversion ratio (FCR) improved by 123.21, 11.66, and 38.72%, respectively, compared to the control group. The dose-response analysis demonstrated a strong positive correlation (R2=0.96) between SM levels and weight increase, and a strong negative correlation (R2=0.88) between SM levels and FCR. The antioxidant enzyme activities of larvae given SM-enriched diets were significantly greater than those of the control group. Compared to the control group, the CAT and SOD improved by 81.77 and 5.08 % in the SM600 group. In addition, the saturated fatty acid content reduced while the unsaturated fatty acid content increased, particularly in the SM600 group. The results indicate that supplementing the micro diet of European seabass larvae during weaning with SM at a dose of 600 mg kg-1 increases growth, survival, antioxidant status, and fatty acid profiles.

Heterologous Expression of Three Transcription Factors Differently Regulated Astragalosides Metabolic Biosynthesis in Astragalus membranaceus Hairy Roots

Astragalus membranaceus has been used as a highly popular Chinese herbal medicine for centuries. Triterpenoids, namely astragalosides I, II, III, and IV, represent the main active compounds in this plant species. Transcription factors have a powerful effect on metabolite biosynthesis in plants. We investigated the effect of the Arabidopsis MYB12, production of anthocyanin pigment 1 (PAP1), and maize leaf color (LC) transcription factors in regulating the synthesis of astragaloside metabolites in A. membranaceus. Overexpression of these transcription factors in hairy roots differentially up-regulated these active compounds. Specifically, the overexpression of LC resulted in the accumulation of astragalosides I–IV. The content of astragalosides I and IV were, in particular, more highly accumulated. Overexpression of MYB12 increased the accumulation of astragaloside I in transgenic hairy roots, followed by astragaloside IV, and overexpression of PAP1 resulted in the increased synthesis of astragalosides I and IV. In addition, we found that overexpression of PAP1 together with LC increased astragaloside III levels. At the transcriptional level, several key genes of the mevalonate biosynthetic pathway, especially HMGR1, HMGR2, and HMGR3, were up-regulated differentially in response to these transcription factors, resulting in astragaloside synthesis in the hairy roots of A. membranaceus. Overall, our results indicated that heterologous expression of Arabidopsis MYB12, PAP1, and maize LC differentially affected triterpenoids biosynthesis, leading to the increased biosynthesis of active compounds in A. membranaceus.

Immunosuppressive Effects of Thallium Toxicity in Nile Tilapia Fingerlings: Elucidating the Rescue Role of Astragalus membranaceus Polysaccharides

This study evaluated the immunotoxic effects of thallium (Tl) in Nile tilapia fingerlings and the recovery role of dietary Astragalus membranaceus polysaccharides (ASs). An 8-week experiment was designed where 180 fishes were randomly and equally assigned in triplicates into the six groups: the control group (CNT) was reared in unpolluted water and fed a commercial diet, two groups were fed a well-balanced commercial diet plus 1.5 and 3.0 g AS/kg diet (AS0.15 and AS0.30), respectively, the fourth group was exposed to a sublethal dose of Tl (41.9 μg l^-1) [equal to 1/10 of 96-h lethal concentration 50 (LC50)], and the last two groups were fed 0.15 and 0.3% AS, respectively, and concurrently exposed to Tl (41.9 μg l^-1) (AS0.15+Tl and AS0.30+Tl). Fish hematobiochemical parameters, serum immunity [nitric oxide, total immunoglobulin M (IgM) levels, and lysozyme activity], transcription of hepatic interferon-γ (IFN-γ), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α), and resistance to Aeromonas hydrophila (A. hydrophila) were assessed. Hematobiochemical parameters and serum immune indices were significantly decreased in the fish group exposed to sublethal Tl concentration compared to the CNT group. Furthermore, Tl exposure significantly induced overexpression of IL-1β, TNF-α, and IFN-γ genes (4.22-, 5.45-, and 4.57-fold higher, respectively) compared to CNT values. Tl exposure also increased the cumulative mortality (%) in Nile tilapia challenged with A. hydrophila. Remarkably, the groups fed AS0.15+Tl and AS0.30+Tl significantly ameliorated all the aforementioned parameters, but did not reach CNT values. Our findings suggest the possible immunomodulating roles of dietary AS in recovering the immunotoxic effects of Tl in Nile tilapia. We can conclude that dietary AS would be useful for maintaining the immunity of Nile tilapia fingerlings.

The Optimization of Dietary Protein Level and Carbon Sources on Biofloc Nutritive Values, Bacterial Abundance, and Growth Performances of Whiteleg Shrimp (Litopenaeusvannamei) Juveniles

A biofloc technology-based 75-day indoor growth trial in an 80 L glass aquaria was conducted to evaluate the effects of two different carbon sources (sugarcane bagasse, SB, and wheat flour, WF) on the biofloc composition, bacterial abundance, and growth of whiteleg shrimp (Litopenaeus vannamei) juveniles (0.23 ± 0.04 g). Three different levels of dietary protein content (250, 300, and 350 g protein kg−1 diet) and two carbon sources (SB and WF) were applied (SB250, WF250, SB300, WF300, SB350, and WF350, respectively), comparing to a controlled diet without biofloc and fed on a 450 g protein kg−1 diet (C450). With the addition of SB and WF, water quality was in the ideal recommended ranges for L. vannamei culture. At the end of the experiment, the biofloc volume increased with increasing dietary protein levels. The nutritional value of biofloc in different treatments was influenced by dietary protein and added SB and WF. Increasing dietary protein significantly increased the protein and lipid contents of the produced biofloc. The use of WF as a carbon source significantly increased lipids and nitrogen-free extract in the biofloc. The total heterotrophic bacterial (THB) count was significantly higher (p < 0.05) in WF300 and WF350 than in the other treatments. The mean effect of the protein levels and carbon source was significantly reported, whereas the highest significant THB count was recorded with 300 dietary protein and using WF as a carbon source. The growth performances of L. vannamei fed with biofloc treatments were significantly (p < 0.05) higher than the C450 group. The highest final weight and weight gain were recorded in SB350 treatment. The feed conversion ratio was not affected by reducing dietary protein levels; meanwhile, the protein efficiency ratio increased significantly in biofloc treatments than in the control. Overall, the results demonstrate that, compared to the control treatment of 450 dietary protein, the biofloc treatments using WF as a carbon source could compensate for the reduction in the dietary protein levels in the diet of L. vannamei and maintain higher zootechnical performance.

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

It is generally accepted that Astragalus polysaccharides (APS) supplementation can makes beneficial effects to fish. However, the adverse effects of APS to fish remains poorly understood. In the present study, Asian seabass Lates calcarifer were studied to assess the influence of different doses of APS on growth, health and resistance to Vibrio harveyi. Results showed that supplemental APS with 0.10 to 0.20% significantly boosted the growth performance, the protease and lipase activities of L. calcarifer. Compared with control diet, the villus length of L. calcarifer fed with APS supplemented diets was significantly higher. L. calcarifer fed with APS supplementation diets also significantly facilitated the antioxidant capacity and immune function. Meanwhile, supplemental APS with 0.10 to 0.15% significantly promoted liver health by up-regulating the expression of anti-inflammatory cytokines and down-regulating the expression of pro-inflammatory cytokines. Furthermore, survival rate of L. calcarifer challenged with V. harveyi was higher in diets supplemented with APS compared to the control. However, 0.20% APS significantly hindered the growth performance and caused immunostimulatory fatigue in L. calcarifer compared to 0.10% APS. Taken together, the present study demonstrates that supplementation APS with 0.10% is the optimal level for promoting the growth performance, health and resistance to V. harveyi of L. calcarifer, while 0.20% APS exerts adverse effects on L. calcarifer. Our findings provide novel recommendations for the application of APS supplementation in farmed fish.

Astragalus membranaceus polysaccharides modulate growth, hemato-biochemical indices, hepatic antioxidants, and expression of HSP70 and apoptosis-related genes in Oreochromis niloticus exposed to sub-lethal thallium toxicity

A 60-day experiment was performed to assess the efficacy of dietary Astragalus membranaceus polysaccharides (ASP) in attenuation of sub-lethal thallium (Tl) toxicity in Nile tilapia. Six experimental groups (in triplicates) were designed where a fish group was raised in clean water and fed basal diet and served as control (CONT), two groups were fed the basal diet supplemented with 0.15% and 0.30% ASP (ASPL and ASPH), Tl-intoxicated group exposed to 1/10 of 96-h LC50 (= 41.9 μg/L), and two other groups were fed 0.15% and 0.30% ASP and concomitantly exposed to 41.9 μg Tl/L (ASPL-Tl and ASPH-Tl). At the end of the experiment, fish behavioral responses, clinical signs, survivability, growth, whole-body composition, intestinal digestive enzymes, serum biochemical parameters, hepatic antioxidative biomarkers, and transcription of stress and apoptosis genes were assessed. Results showed that the whole-body composition, intestinal α-amylase and protease enzymes, serum AST and blood urea levels, and hepatic GSH were not significantly different among groups (P > 0.05). The Tl-intoxicated fish group was off food, had darkened skin, showed restlessness and hyperexcitability, and high mortalities. FBW, WG, SGR and FI were significantly decreased alongside increase FCR in the Tl-exposed group. Tl exposure caused significant increases (P < 0.05) in intestinal lipase enzyme and serum indices such as ALT, creatinine, total cholesterol, triglycerides, glucose, and cortisol levels. Moreover, a significant decreases in hepatic CAT and SOD enzyme activities and significant increases in hepatic MDA contents were also noticed (P < 0.05). Furthermore, Tl exposure induced significant upregulation of hepatic HSP70 and apoptosis-related genes (p53 and caspase 3). Interestingly, dietary supplementation with ASP in ASPL-Tl and ASPH-Tl groups modulated the parameters mentioned above but still not reached the CONT values. Altogether, this study suggests that ASP could be beneficial in the modulation of sub-lethal Tl toxicity effects in Nile tilapia. Additionally, we can conclude that using natural feed supplements such as ASP in aquafeed might be necessary for maintaining the overall health performances of Nile tilapia.

Systematic exploration of Astragalus membranaceus and Panax ginseng as immune regulators: Insights from the comparative biological and computational analysis

BACKGROUND

Immune system plays a decisive role for defending various pathogenic microorganisms. Astragalus membranaceus (AM) and Panax ginseng (PG) are two tonic herbs used in traditional Chinese medicine (TCM) as immune booster and help to control diseases with their healthy synergistic effect on immune system.

PURPOSE

This study was aimed to investigate the promote effect and molecular mechanisms of AM and PG on immune system as booster and to control the target diseases using animal and computational systematic study.

METHODS

Computational models including absorption, distribution, metabolism, and elimination (ADME) with weighted ensemble similarity (WES) algorithm-based models and ClueGo network analysis were used to find the potential bioactive compounds targets and pathways, which were responsible for immune regulation. Viscera index analysis, proliferation activity of splenic lymphocytes and cytotoxic activity of NK cells assays were performed to validate the effect of AM and PG on immune system of long-term administrated mice. Metabonomic study of mice plasma was conducted to investigate effect of AM and PG on the endogenous metabolic perturbations, together with correlation analysis.

RESULTS

AM and PG simultaneously showed the ability to strengthen the immune system function including enhancement of spleen and thymus index, proliferation of splenic lymphocytes and cytotoxic activity of NK cells. Besides, the different molecular mechanisms of AM and PG on immune regulation were also investigated by analyzing the potential bioactive compounds, enzymes actions and pathways. Quercetin, formononetin and kaempferol were the main immune-related compounds in AM, while ginsenoside Ra1, ginsenoside Rh1 and kaempferol in PG. About 10 target proteins were found close to immune regulation, including acetylcholinesterase (ACHE, common target in AM and PG), sphingosine kinase 1(SPHK1), cytidine deaminase (CDA), and Choline O-acetyltransferase (CHAT). Glycerophospholipid metabolism was regulated in both AM and PG groups. Pyrimidine metabolism and sphingolipid metabolism were considered as the special pathway in AM groups. Energy metabolism and glycerolipid metabolism were the special pathways in PG groups.

CONCLUSION

A novel comprehensive molecular mechanism analysis method was established and applied to clarify the scientific connotation of AM and PG as immune regulation, with similar herbal tonic effect provided in clinical practice of TCM, which can provide a new line of research for drug development (immune booster) using AM and PG.

Protective potency of Astragalus polysaccharides against tilmicosin- induced cardiac injury via targeting oxidative stress and cell apoptosis-encoding pathways in rat

Tilmicosin (Til) was purposed to be used in the treatment of a wide range of respiratory diseases in livestock. However, undesirable adverse effects, cardiac toxicity, in particular, may be associated with Til therapy. In the present study, the response of adult rats administered Til subcutaneously at different doses (10, 25, 50, 75, and 100 mg/kg b.w.; single injection) was evaluated. Astragalus polysaccharide (AP) at two doses (100 and 200 mg/kg b.w.; intraperitoneally) was investigated for its potential to counteract the cardiac influences, involving the oxidative stress-induced damage and apoptotic cell death, elicited by the Til treatment at a dose of 75 mg/kg b.w. in rats. Til induced mortalities and altered the levels of the biomarkers for the cardiac damage, particularly in the rats treated with the doses of 75 and 100 mg/kg b.w.; similarly, morphological alterations in cardiac tissue were seen at all studied doses. AP was found to cause a significant (P ˂ 0.05) decline in the levels of impaired cardiac injury markers (troponin, creatine phosphokinase, and creatine phosphokinase-MB), improvement in the antioxidant endpoints (total antioxidant capacity), and attenuation in the oxidative stress indices (total reactive oxygen species, 8-hydroxy-2-deoxyguanosine, lipid peroxides [malondialdehyde], and protein carbonyl), associated with a significant (P ˂ 0.05) modulation in the mRNA expression levels of the encoding genes (Bcl-2, Bax, caspase-3, P53, Apaf-1, and AIF), related to the intrinsic pathway of apoptotic cell death in the cardiac tissue. AP administration partially restored the morphological changes in the rat's heart. The highest protective efficacy of AP was recorded at a dose level of 200 mg/kg b.w. Taken together, these results indicated that AP is a promising cardioprotective compound capable of attenuating Til-induced cardiac impact by protecting the rat cardiac tissue from Til-induced apoptosis when administered concurrently with and after the Til injection.

Effects of dietary Senecio scandens buch-ham extracts on growth performance, plasma biochemical, histology and the expression of immune-related genes in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀)

The study mainly aimed at the effects of dietary Senecio scandens buch-ham extract (SSBE) on the growth performance, body composition, plasma biochemical index, intestinal and liver histology and the expression of antioxidant, apoptosis and inflammatory related genes in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). Basal diets supplemented with SSBE (10:1) 0%, 0.05%, 0.1%, 0.2% and 0.4% were fed hybrid grouper for 8 weeks. The results showed that WGR and SGR were significantly increased in the week 2 and week 4 in Diet 0.05% group (P < 0.05). The total protein, globulin and albumin significantly increased whereas alanine aminotransferase, triglyceride and alkaline phosphate in the plasma were significantly decreased in Diet 0.1% group (P < 0.05). The villi length, width, muscle thickness and the cross-sectional area of intestine were improved in Diet 0.05% and Diet 0.1% group. The expression levels of PPAR-α and CPT-1 in the liver of hybrid grouper were significantly increased following the supplementation of SSBE (P < 0.05). The expression levels of antioxidant related genes (CAT, GPX, GR and Keap1) and anti-inflammatory factor (IL-10) in liver, head kidney and spleen of hybrid grouper decreased significantly (P < 0.05). In addition, diets supplemented with 0.05%-0.1% SSBE had a good liver-protecting effect, but it would have a detrimental effect on hepatocytes when the content exceeds 0.2%. The above results indicated that the suitable additive amount of SSBE in hybrid grouper feed was 0.05%-0.1%.

Effects of Lycium barbarum polysaccharides on immunological parameters, apoptosis, and growth performance of Nile tilapia (Oreochromis niloticus)

In this study, the effect of Lycium barbarum polysaccharides (LBP) on immunological parameters, apoptosis, and growth performance of Nile tilapia (Oreochromis niloticus) was investigated. Dietary supplementation with LBP significantly increased complement 3 (C3) activity and promoted interleukin IL-1β gene expression in spleen tissue, significantly reduced apoptosis in spleen tissue, increased the specific growth rate (SGR), relative length gain (LG), and relative weight gain (WG) of Nile tilapia. However, dietary supplementation with LBP did not have a significant effect on serum alkaline phosphatase (AKP), malondialdehyde (MDA), and superoxide dismutase (SOD), blood constituents, apoptosis, or gene expression of IL-1β in liver tissue. Overall, the results showed that dietary supplementation with LBP increased the nonspecific immunity of Nile tilapia and reduced the apoptosis rate to promote growth and development. Thus, LBP has potential for use as a new immunostimulant in aquaculture.

Astragalus membranaceus nanoparticles markedly improve immune and anti-oxidative responses; and protection against Aeromonas veronii in Nile tilapia Oreochromis niloticus

The effects of dietary administration of Astragalus membranaceus nanoparticles (ANP) on immune and anti-oxidative responses, growth performance and disease resistance of Oreochromis niloticus were evaluated in the present study. Fish were divided into three groups and received the ANP at rates of 0 (control), 1, and 2%/kg diet for four weeks. After the four-week feeding trial, three fish from each replicate were sampled for immune and anti-oxidative responses evaluation, ten fish from each group were challenged with A. veronii, and nine fish from each group were subjected to cold and hypoxia challenges. It was obvious from the results that ANP significantly enhanced lysozyme activity and nitrous oxide (NO) activities, as well as improved superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities. Also, aspartate aminotransferase, alanine transaminase, glucose, and cortisol measurements showed significantly lower levels in incorporated groups compared to the control. Growth performance; and amylase and lipase digestive enzymes activities also showed markedly improved results. Expression of heat shock protein 70 (HSP70) and interleukin 1, beta (IL-1β) genes were significantly upregulated throughout the entire experimental period. When challenged with A. veronii, the mortality of treated groups was significantly (P < 0.05) lower than the control. Current results proofs that dietary ANP had a synergistic effect on immune and anti-oxidative responses, growth performance and disease resistance of Oreochromis niloticus.

Immunomodulatory activities of proteins from Astragalus membranaceus waste

BACKGROUND

Astragalus membranaceus is a traditional Chinese medicine that has a long history of medical applications. It is of interest to investigate the functional components of A. membranaceus waste with regard to its development and utilization and increasing resource utilization.

RESULTS

The protein AMWP was isolated from the A. membranaceus waste. This protein was further purified by DEAE-cellulose-52 chromatography and Sephadex G-200 size-exclusion chromatography to obtain three fractions, named AMWPDG2, AMWPDG4 and AMWPDG6. Then, their immunomodulatory activities were evaluated by using cell model experiments. The results indicated that the protein fractions could significantly increase the proliferation of splenic lymphocytes, peritoneal macrophages and bone-marrow-derived cells (BMDCs). AMWPDG2 showed the highest immunocompetence. AMWPDG2, AMWPDG4 and AMWPDG6 not only significantly improved the phagocytosis and immunomodulatory factors (interleukin (IL)-6, tumor necrosis factor-α, nitric oxide, hydrogen peroxide) secretion of peritoneal macrophages, but also promoted the expression of inflammatory cytokines (IL-6, IL-12 p40, IL-1β, IL-1α) and chemokines (CXCL1, CCL3) in BMDCs.

CONCLUSION

Taken together, these results indicated that three protein fractions from the A. membranaceus waste might be a potential natural immunomodulator. Moreover, it also provided the theoretical basis for further researching the mechanism of AMWPDG2, AMWPDG4 and AMWPDG6 on improving the immune response. © 2019 Society of Chemical Industry.

Traditional Chinese Medicine Enhances Growth, Immune Response, and Resistance to Streptococcus agalactiae in Nile Tilapia

Herbal supplements are suitable for improving fish health and combating diseases in fish culture. However, the mechanism of action of many herbal mixtures remains unclear. This study was conducted to evaluate the effects of traditional Chinese medicine (TCM; a mix of Astragalus membranaceus, Angelica sinensis, and Crataegus hupehensis at a ratio of 1:1:1 on a weight basis) on growth, immune response, and disease resistance in Nile tilapia Oreochromis niloticus. Experimental fish (mean ± SE weight = 57 ± 1 g) were divided into two groups: a control group and a TCM (10 g/kg) group. After 4 weeks of the experimental trial, a significant increase in weight gain and specific growth rate and a lower feed conversion ratio were observed in fish fed a TCM-supplemented diet compared with control fish. Similarly, the immune response of Nile Tilapia in the TCM group showed enhanced lysozyme, superoxide dismutase, catalase, and immunoglobulin levels compared with the control fish. In comparison with the control, fish fed TCM showed significant up-regulation of β-defensin, lysozyme, heat shock protein 70, superoxide dismutase, and catalase genes in the intestine and head-kidney tissues. After a Streptococcus agalactiae challenge, survival of Nile Tilapia in the TCM group was 70% compared with 35% in the control. These results indicate that the TCM mixture in this study can elevate the immune response and disease resistance of Nile Tilapia.

Effects of Astragalus polysaccharides (APS) and chitooligosaccharides (COS) on growth, immune response and disease resistance of juvenile largemouth bass, Micropterus salmoides

The effects of oral administration of Astragalus polysaccharides (APS) and chitooligosaccharides (COS), single or combined, on the growth performance, immunity and disease resistance of M. salmoides were investigated. Largemouth bass juvenile were divided into 4 groups and each group was fed with diets supplemented with or without immunostimulant for 8 weeks. After 8 weeks of feeding trial, five fish per tank were sampled for immunity determination, ten fish per tank were challenged by A. hydrophila. The results showed that the largemouth bass fed with two immunostimulants alone or in combination significantly enhanced the final weight and specific growth rate (SGR), decreased feed conversion ratio (FCR) (P < 0.05). However, there were no significant differences (P < 0.05) in specific growth rate (SGR) between dietary COS and dietary APS. In addition, both COS and APS upregulated respiratory burst activity (RBA), phagocytic activity (PA), lysozyme activity and superoxide dismutase (SOD) activity. Meanwhile, COS also exhibited a increase in total leukocyte count, nitric oxide (NO) content and inducible nitric oxide synthase (iNOS) activity compared to the control. When challenged with A. hydrophila, the mortality of groups fed with COS and/or APS was lower than the control (P < 0.05). Under the experimental conditions, dietary APS and COS had a synergistic effect on lysozme activity, iNOS activity, NO content and disease resistance of fish (P < 0.05).

Enhancing growth and non-specific immunity of grass carp and Nile tilapia by incorporating Chinese herbs (Astragalus membranaceus and Lycium barbarum) into food waste based pellets

The effects of Astragalus membranaceus and Lycium barbarum on the growth performance and non-specific immunity of grass carp and Nile tilapia were studied. Herb extracts of Chinese medicinal herbs (2 g kg^-1 or 20 g kg^-1) were incorporated into food waste based fish feed pellets. Fish growth and selected non-specific immune parameters of grass carp and Nile tilapia were studied in two separate feeding trials. Both grass carp and Nile tilapia fed diets of feed pellets containing 2 g kg^-1Lycium barbarum extract achieved the best relative weight gain, feed conversion ratio, specific growth rate and protein efficiency ratio among all experimental diets. Fish fed with diets containing 2 g kg^-1Lycium barbarum also resulted in significantly higher total immunoglobin, bactericidal activity and anti-protease activity; and also a lower mortality when challenged with pathogenic bacteria. On the other hand, both fish species fed with diets containing 20 g kg^-1 of Astragalus membranaceus and 20 g kg^-1Lycium barbarum, resulted in significantly impaired weight gain. In addition, incorporation of 2 g kg^-1Lycium barbarum extract would be a more suitable dose for both fish species, in terms of achieving better feed conversion ratio, specific growth rate, protein digestibility, and improved non-specific immune parameters. Based on this study, it can be concluded that waste based feed pellets incorporated with Chinese medicinal herb extracts have the ability to enhance growth and immunity of fish. Therefore, the use of Chinese medicinal herbs in aquaculture should be encouraged, in order to replace certain antibiotics known to impose environmental and health effects through the discharge of aquaculture effluents.