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1.
Sixteen candidate disease‐resistant parameters were selected through which to evaluate the acute hepatopancreatic necrosis disease (AHPND)‐resistant capability of Exopalaemon carinicauda after three generations of selection for AHPND‐causing strain of Vibrio parahaemolyticus (VPAHPND) resistance in our previous study. However, these parameters required further verification. In this study, another AHPND‐resistant E. carinicauda series was obtained through a short‐term selection procedure, consisting of three virulent challenge rounds of selection (about three‐week interval for each challenge) with VPAHPND infection. After this selection, the survival rate at 144 hr post infection (hpi) increased from 23.33% to 37.78% and the observed 48‐hr LD50 of VPAHPND to shrimp increased from 105.5 cfu/ml to 106.5 cfu/ml. Then, the immune response of this AHPND‐resistant E. carinicauda was studied using the 16 candidate AHPND‐resistant parameters selected for in our previous study. The improved VPAHPND clearance rate in hpi, increased total haemocyte counts, haemocyanin concentration, alkaline phosphatase activity and expressions of six immune‐related genes (Tollip and ALF in haemocytes and hepatopancreas; lysozyme, crustin and cathepsin B in hepatopancreas; and LGBP in haemocytes) at 24 hpi after the three‐round challenge selection suggest that these immune parameters may be reliable markers for the evaluation of the physiological status and potential AHPND‐resistant phenotypes in E. carinicauda.  相似文献   

2.
Outbreaks of acute hepatopancreatic necrosis disease (AHPND) have caused great economic losses to many shrimp‐producing countries in Asia since its first appearance in 2009. The causative agent was reported in 2013 as specific isolates of Vibrio parahaemolyticus (VPAHPND) that were later found to harbor a plasmid (pVA) encoding the Pir‐like binary toxin genes Pir vpA and Pir vpB. VPAHPND isolates colonize the shrimp stomach and release the binary toxins that cause massive sloughing of tubule epithelial cells followed by shrimp mortality. More recent information indicates that pVA plasmid and variants occur in many V. parahaemolyticus serotypes and also in other Vibrio species such as Vibrio campbellii, Vibrio harveyi, and Vibrio owensii. Information on such genomic and proteomic studies of different VPAHPND isolates from different countries are reviewed. A cohort study carried out in Thailand in 2014 indicated that AHPND outbreaks account for only a portion of the disease outbreaks reported by shrimp farmers as outbreaks of early mortality syndrome (EMS). It is recommended that a regional research network and surveillance program for newly emerging or re‐emerging pathogens be established to speed up the process of diagnosis and the implementation of coordinated control measures and to avoid a repeat of the EMS/AHPND scenario.  相似文献   

3.
Shrimp culture is a well‐established and fast‐growing industry that produces economic and social benefits in many countries. However, during the last years, it was severely affected by the emergence of the Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Disease (AHPND). This disease is mainly attributed to Vibrio parahaemolyticus, and currently, there is no effective cure or treatment. In this study, the use of T2A2 and VH5e bacteriophages was evaluated to control different AHPND‐positive strains (presumptively identified as V. parahaemolyticus, VPAHPND) under laboratory conditions. Lytic effect of T2A2 and VH5e bacteriophages against different strains isolated from AHPND outbreaks was corroborated. In addition, the effectiveness of the mixture of both phages was tested on a brine shrimp experimental infection model using three highly virulent VPAHPND strains. It has been found that phage‐treated brine shrimp had significantly higher survival percentage compared with non‐treated groups (p < .001). Also, phage cocktail was found to be harmless to the organisms. These results suggest that the phage mixture is worth considering as a possible control measure for positive AHPND strains, although it is clear that further and more extensive testing is needed.  相似文献   

4.
The present study investigates the effects of dietary commercial Bacilli probiotic (Bacillus subtilis and Bacillus licheniformis) on the growth performance, feed efficiency, body composition and immune parameters of Litopenaeus vannamei. The L. vannamei postlarvae were supplied and acclimated (in 500‐L tanks) to laboratory conditions for 14 days. The shrimps were fed with diets containing 1 × 104 and 1 × 108 CFU/g probiotic Bacilli for 60 days. At the end of the feeding trial, growth performance parameters, body composition, serum biochemical parameters and the hemocytes count were evaluated. Shrimps fed diets supplemented with 1 × 104 and 1 × 108 CFU/g probiotic Bacilli showed improved weight gain, total length, specific growth rate, FCR and survival compared with the control group. The body composition studies revealed higher dry matter, crude protein and ash in shrimps fed with 1 × 104 and 1 × 108 CFU/g probiotic Bacilli. Also, dietary administration of 1 × 104 and 1 × 108 CFU/g probiotic Bacilli decreased serum glucose and cortisol levels. However, significantly increased total protein, lysozyme and hemocyte cell count were noticed in shrimps fed 1 × 104 and 1 × 108 CFU/g probiotic Bacilli. In general, the findings of this study proved that oral administration of 1 × 104 and 1 × 108 CFU/g commercial probiotic Bacilli improved growth performance, feed utilization and immune parameters in whiteleg shrimp (Litopenaeus vannamei).  相似文献   

5.
Acute hepatopancreatic necrosis disease (AHPND) causes massive mortality in shrimp ponds within the first month poststocking. The causative agent is a specific strain of Vibrio parahaemolyticus (VPAHPND) that has acquired the capability to produce virulent binary toxins called ToxA and ToxB. This study aims to test the effect of the addition of an autoinducer‐2‐containing cell‐free supernatant (CFS) from the mutant Vibrio harveyi (VH) on growth and toxin production of VPAHPND. The relative AI‐2‐like activity in CFS was detected by luminescence assay. The effect of CFS (5 and 9%) on growth and toxin production of VPAHPND was evaluated. Compared to the control culture (without CFS‐VH addition), the addition of either 5 or 9% CFS‐VH affected the growth at the initial stage of VPAHPND. Similar growth profiles of VPAHPND were found with the addition of CFS‐VH at both concentrations. Western blot analysis suggests that the addition of CFS‐VH affected the production of both toxins. ToxA could be detected at the early hour post‐CFS‐VH inoculation, whereas the high amount of ToxB was detected when 5% CFS‐VH was added. However, interfering with the AI‐2 function with furanone, the AI‐2 antagonist resulted in a slight delay in the production of both toxins. Results from this study will help to design a novel strategy to control AHPND in shrimp culture.  相似文献   

6.
This study aimed to develop a synbiotic combination with probiotic, Lactobacillus plantarum 7–40 and one of three prebiotics, fructooligosaccharide (FOS), galactooligosaccharide (GOS) and mannan oligosaccharide (MOS). The best in vitro growth was observed when probiotic was cultured in the medium containing either FOS or GOS as the sole of carbon source. The analysis of enzyme activity revealed that GOS induced the highest activities of protease and β‐galactosidase of probiotic. Based on the findings, probiotic + GOS were selected as synbiotic to evaluate if it could promote the growth of white shrimp, Litopenaeus vannamei. For this, four diets, including a basal diet with no GOS or probiotic (control), 0.4% GOS (PRE), 108 CFU probiotic kg?1 (PRO) and 0.4% GOS in combination with 108 CFU probiotic kg?1 (SYN), were fed to shrimp for 60 days, and then the growth performance, intestinal microbiota (including total Vibrio counts, VBCs; and lactic acid bacteria, LAB) and digestive enzyme (including protease, leu‐aminopeptidase and β‐galactosidase) were evaluated. The weight gain (WG) of shrimp fed the PRO did not significantly differ from those of control (p > .05). Shrimp fed the SYN had significantly higher WG compared with the other treatments (p < .05). In addition, the SYN‐fed shrimp had significantly higher LAB and protease, leu‐aminopeptidase and β‐galactosidase activity (p < .05). The lowest presumptive Vibrio count (VBC) was also observed in intestines of SYN‐fed shrimp. Therefore, we suggested that Lac. plantarum 7–40+ GOS can be used as a synergistic synbiotic for shrimp culture.  相似文献   

7.
The present work evaluated the use of molasses as a carbon source during the nursery rearing of Farfantepenaeus brasiliensis in a Biofloc technology system. During a 30 days trial, three replicate tanks were randomly assigned to the following treatments: 1.) molasses (with molasses addition) and 2.) control (without molasses addition). Bacteriological analysis was used to quantify the abundance of presumptive Vibrio spp. between control and molasses treatment. The concentration of this microorganism was lower in molasses compared with control. For the immunological analysis, shrimp haemolymph was collected to determine the total haemocyte count and the total protein concentration. The immunological results were not different between treatments. The performance results of shrimp reared with molasses addition showed that the survival rate (88.87 ± 6.36), the mean final weight (1.22 ± 0.38) and the specific growth rate (0.0309 ± 1.06) were significantly higher compared with control (80.5 ± 2.42; 1.03 ± 0.13; 0.0256 ± 0.97 respectively). Moreover, the addition of molasses contributed to the maintenance of water quality and lower concentration of presumptive Vibrio spp. The control presented an unstable variation of Vibrio spp. reaching values of 80 × 102 CFU/ml, while the highest result of molasses was 20 × 102 CFU/ml, confirming the beneficial effects of molasses addition.  相似文献   

8.
Litopenaeus vannamei is economically important shrimp species in worldwide aquaculture. This study was conducted to assess the effect of different levels of probiotic Pediococcus pentosaceus (PP) on growth performance, feed utilization, digestive enzyme activity, intestinal microflora count and body composition of L. vannamei. Four diets containing different concentrations [0 (PP0), 106 (PPI), 107 (PPII) and 108 (PPIII) CFU/g] of PP were formulated. After 8 weeks feeding trial, the experimental shrimps were challenged with Vibrio anguillarum and noted the surveillance. At the end of the feeding trial, the obtained results revealed a significant increase (p < .05) in final body weight, final length, weight gain (WG), survival rate, protease and amylase activities, lactobacillus sp. and Bacillus sp. intestinal count, total haemocyte counts (THC) and lysozyme activity in PPIII group when compared with the other groups. Similarly, WG, amylase activity, Bacillus sp. count, THC and lysozyme activity were significantly enhanced in case of PPII compared to the control group (p < .05). Interestingly, FCR and Vibrio sp. counts were significantly decreased in case of PPIII group when compared to the other groups (p < .05). Also, significant level of surveillance was noted in the challenging test with V. anguillarum. These results suggested that the P. pentosaceus improved the growth performance, digestive enzyme activity, immunity and tolerance against V. anguillarum of L. vannamei.  相似文献   

9.
An 8‐week study was conducted to explore the results of Macsumsuk® as a feed additive on the stress tolerance and growth of Litopenaeus vannamei in 15 culture tanks of 36 L each. Three hundred shrimp averaging 0.1 ± 0.01 g were fed with five isonitrogenous (48.38 ± 0.38% CP) diets (in triplicate groups) containing kaolinite (Macsumsuk®) at 0%, 0.3%, 0.6%, 1.2% and 2.4%, namely Mk0, Mk0.3, Mk0.6, Mk1.2 and Mk2.4. Specific growth rate (SGR) and weight gain (WG) of shrimp fed diets Mk1.2 and Mk2.4 were significantly better than those of shrimp fed diet Mk0 (p < .05). However, SGR and WG of shrimp fed diets Mk0.6, Mk1.2 and Mk2.4 were not significantly different. Protein efficiency ratio (PER) and feed efficiency (FE) of shrimp fed diets Mk1.2 and Mk2.4 were significantly better than those of shrimp fed diets Mk0, Mk0.3 and Mk0.6. Furthermore, the survival of shrimp fed diet Mk2.4 was significantly lower than that of shrimp fed diet Mk0.6 (p < .05). Cumulative mortality of shrimp fed diet Mk1.2 was significantly lower than that of shrimp fed diet Mk0 at 1–1.5 hr post‐stress to low dissolved oxygen (from 6.1 mg/L to 2.9 mg/L) and 4–5 hr post‐stress to low salinity (from 32‰ to 1‰) (p < .05). The optimum dietary Macsumsuk® level for juvenile L. vannamei was determined as 1.97% by the polynomial regression analysis of weight gain.  相似文献   

10.
The influence of dietary supplementation of Lactobacillus acidophilus, on growth performance, digestive enzyme activities, gut histomorphology and gut microflora were evaluated in juveniles striped catfish (Pangasianodon hypophthalmus). Five experimental diets were formulated by supplementing 0, 103, 105, 107 and 109 CFU/g L. acidophilus in fishmeal and casein‐based semi‐purified diet. Triplicate groups of striped catfish (21.69 ± 0.18 g) were stocked in 15 fiberglass tanks with stocking density of 25 individuals per tank and fed twice daily at 2.5% of the fish body weight for 12 weeks. Weight gain, specific growth rate, feed conversion ratio and the protein efficiency ratio were significantly higher in fish fed with 105 and 107CFU/g L. acidophilussupplemented diets compared with the other treatment groups. Compared with the control and fish fed low (103 CFU/g) L. acidophilus supplementation, those fed with 105 and 107 CFU/g had significantly higher (p < 0.05) apparent protein digestibility. Inclusion of L. acidophilus at 107 CFU/g diet significantly increased amylase, protease and lipase activities. Microscopic analysis showed that the villi length in both the anterior and posterior gut and microvilli length in the posterior gut increased significantly in fish fed L. acidophilus supplementation at 105 and 107 CFU/g of diet. The fish fed L. acidophilus supplemented diets significantly increased the total lactic acid bacteria counts in the gut of striped catfish compared with the control‐fed group. Based on gut histomorphology and growth performance, inclusion of L. acidophilus at 105 CFU/g appears to have the most positive effect on striped catfish farming.  相似文献   

11.
Acute hepatopancreatic necrosis disease (AHPND) has caused losses to shrimp farmers worldwide owing to Vibrio parahaemolyticus (VPAHPND). Selective breeding for disease resistance of shrimp was used as an alternative strategy for disease control. Five subsamples of shrimp from 20 full-sib families were subjected to a cohabitation challenge test. Juveniles of P. semisulcatus (mean weight 2.5 ± 0.17 g) were tested for survival after challenge with VPAHPND. Mortality in the challenge test was recorded daily, and the experiment was terminated after 96 days when the mortality ceased. Moderate heritabilities were estimated in resistance to VPAHPND based on a linear model (LM) and threshold model (TM). This indicates that disease resistance is a heritable trait, and a challenge test may serve as a basis for selection for resistance to VPAHPND in P. semisulcatus. However, further investigation is needed to confirm and quantify the additive genetic variation for resistance to VPAHPND in P. semisulcatus.  相似文献   

12.
Pacific white shrimp Litopenaeus vannamei (1050 individuals with initial weight of 1.01 ± 0.001 g) were fed either control diet or one of six dietary astaxanthin (AX) concentration (25, 50, 75, 100, 125 and 150 mg kg−1) diets for 56 days in 35 tanks (30 shrimp per tank). After 56 days of culture, shrimp‐fed AX125 and AX150 diets had higher (P < 0.05) weight gain, specific growth rate, total antioxidant status and lower (P < 0.05) superoxide dismutase (SOD), catalase (CAT) than shrimp fed control diet. After low dissolved oxygen stress for 1 h, survival rate of shrimp fed AX75, AX100, AX125 and AX150 diets was higher (P < 0.05) than that of shrimp fed control diet. Hypoxia inducible factor‐1α (HIF‐1α), cytosolic manganese superoxide dismutase (cMnSOD) and CAT mRNA expression levels of shrimp fed seven diets were significantly down‐regulated under hypoxia than under normoxia, but their expression levels were higher under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet. About 70‐kDa heat‐shock protein (Hsp70) mRNA expression level of shrimp fed seven diets was significantly up‐regulated under hypoxia than under normoxia, but its expression level was lower under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet.  相似文献   

13.
The experiments explored the pharmacokinetics (PK) properties of oxolinic acid (OXA) after oral administration at three dosages (10, 30 and 80 mg/kg) via medicated feed in the shrimp. The results showed that the Cmax values of 4.31, 14.93 and 16.62 mg/L and AUC0–∞ values of 92.61, 252.30 and 364.27 mg hr?1 L?1 were observed at three OXA dosage groups in the haemolymph respectively. In the hepatopancreas, Cmax values of 7.90, 27.23 and 60.51 mg/kg and AUC0–∞ values of 42.01, 133.06 and 219.06 mg hr?1 L?1 were observed at 0.5 hr post administration respectively. In the muscle, Cmax values of 1.62, 5.80 and 7.36 mg/kg and the AUC0–∞ values of 25.64, 98.10 and 134.24 mg hr?1 L?1 were observed at 2 hr post administration respectively. In the gills, Cmax values of 2.87, 8.08 and 12.12 mg/kg and the AUC0–∞ values of 51.38, 118.65 and 206.48 mg hr?1 L?1 were observed at 4 hr post administration respectively. In addition, the in vitro MIC values of OXA at three dosages against 132 strains of Vibrio were examined and showed that the minimum inhibitory concentration (MIC) values for OXA primarily ranged from 0.15–1.25 µg/ml, including eight strains of Vibrio showing MIC values ≥5 µg/ml. The MIC50 and MIC90 values of 132 strains were 0.62 and 1.25 μg/ml respectively. The AUC0–24/MIC90 ratios of Vibrio were 140.4 in 30 mg/kg group. Furthermore, the P‐glycoprotein (P‐gp) expression was determined in shrimp tissues after administration to three dosage groups (10, 30 and 80 mg/kg). The results showed that P‐gp expression was up‐regulated in the hepatopancreas (5.36‐, 13.68‐ and 31.06‐fold respectively) compared with the control group.  相似文献   

14.
The purpose of the present study is to profile the microfloral structure in the intestines of the white shrimp, Litopenaeus vannamei, after being fed a control diet, in comparison with the diets containing Bacillus subtilis E20‐fermented soybean meal (FSBM) or an antimicrobial peptide (AMP) isolated from B. subtilis E20‐FSBM (diets designated FSBMD and AMPD, respectively) for 60 days. Metagenomic data showed detection of eight phyla, 20 classes, 40 orders, 68 families and 96 genera. Despite no statistically significant difference, an evaluation of microbial diversity recorded higher species richness, Shannon–Weaver diversity index and evenness in the AMPD and FSBMD groups, compared to the control diet group. Venn diagrams showed that 58 of the operational taxonomic units (OTUs) were shared among the control, FSBMD and AMPD groups, but additional beneficial microbes were only found in the FSBMD and AMPD groups. In addition to the augmentation of beneficial bacteria in the FSBMD and AMPD groups, the abundance of potential pathogens, Vibrio and Flavobacterium, was lower in the gut of shrimp fed the FSBMD and AMPD. The results clearly suggest that the FSBMD and AMPD have the capability to change the microfloral structure of shrimp intestines and could be used for disease prevention in shrimp aquaculture.  相似文献   

15.
The feeding trial was conducted to evaluate the potentials of Clostridium butyricum in the diet of tilapia. Fish (~14 g) were fed with basal diet supplemented with 0 (Control), 0.5 (C‐1), 1 (C‐2), 2 (C‐3), 4 (C‐4) and 8 (C‐5) g/kg commercial probiotic‐containing C. butyricum (1.5 × 108 CFU/g) for 8 weeks. The results showed that weight gain significantly increased, and feed conversion ratio decreased in the C‐2, C‐3 and C‐4 groups (p < .05). The protein retention (except C‐1 group), lipid retention and apparent digestibility coefficient (ADC) of dry matter in probiotic supplementation groups were significantly enhanced, and ADC of protein in the C‐4 group was also improved (p < .05). The supplementation of probiotic significantly increased villus height in anterior intestines and reduced the numbers of intestinal Escherichia coli (p < .05). High‐throughput sequencing showed that top three phyla namely Planctomycetes in all probiotic‐containing groups, Proteobacteria in the C‐1 and C‐2 groups and Chloroflexi in the C‐3 group had higher level than the NC group. The cumulative mortality was reduced by dietary probiotic after challenging with Aeromonas hydrophila (p < .05). In conclusion, C. butyricum can be supplemented at 1–2 g/kg feed for promoting the growth, feed utilization, gut health and microbiota of tilapia.  相似文献   

16.
Different levels of dietary chitosan on growth performance, survival and stress tolerance to air exposure was studied in tiger shrimp, Penaeus monodon. Shrimp (mean initial wet weight about 1.16 g) were fed with six different diets (C0, C0.05, C0.1, C0.2, C0.3 and C0.4) containing six level of chitosan (0%, 0.05%, 0.1%, 0.2%, 0.3% and 0.4% respectively) in triplicate for 60 days. Growth performance [final body wet weight (FBW); weight gain (WG); biomass gain (BG)] of shrimp fed chitosan‐containing diets were higher (P < 0.05) than that of shrimp fed the basal diet, shrimp fed C0.1 diet showed the highest value of growth performance. Survival of shrimp in C0.1 and C0.2 diet groups were higher (P < 0.05) than that of shrimp in C0, C0.05 and C0.4 diet groups but without statistical difference (P > 0.05) in shrimp fed C0.3 diet group. Whole body and muscle lipid contents decreased with increasing dietary chitosan levels. Plasma total cholesterol and triglyceride contents of shrimp fed C0 diet was significantly higher (P < 0.05) than that of shrimp fed chitosan‐containing diets. Plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities of shrimp fed C0 diet were higher than those of shrimp fed chitosan‐containing diets. Digestive gland malondialdehyde (MDA) and carbonyl protein contents of shrimp fed chitosan‐containing diets were lower (P < 0.05) than that of shrimp fed C0 diet. Total haemocyte count of shrimp fed C0 diet was lower (P < 0.05) than that of shrimp fed chitosan‐containing diets. On the contrary, the haemolymph clotting time of shrimp fed C0 diet was higher (P < 0.05) than that of shrimp fed chitosan‐containing diets. In conclusion, all results suggested that dietary intake containing 0.1% and 0.2% chitosan enhanced the growth of shrimp, whereas a higher level than 0.3% and 0.4% decreased growth of shrimp. Second‐degree polynomial regression analysis of WG and BG indicated that the optimum supplement of dietary chitosan level should be 0.19–0.21%.  相似文献   

17.
The goal of this study was to investigate the effects of dietary supplementation with β‐glucan and microencapsulated probiotics (Bacillus subtilis or Pediococcus acidilactici) on growth performance, body composition, haemolymph constituents, and intestinal morphology and microbiota of the Pacific white shrimp Litopenaeus vannamei. Four treatment diets [basal diet (C), β‐glucan‐containing diet (β‐glu), β‐glucan plus B. subtilis‐containing diet (β‐glu+Bs), and β‐glucan plus P. acidilactici‐containing diet (β‐glu+Pa)] were fed to L. vannamei for 90 days. Shrimp fed the β‐glu and β‐glu+Pa diets exhibited similar growth performance and body protein content, which were significantly higher than those of shrimp fed the control diet (P < 0.05). No significant differences in haemolymph triglyceride, cholesterol, protein, haemolymph urea nitrogen or chloride were detected among the experimental diets. However, dietary β‐glucan alone increased the haemolymph glucose level and osmolarity (P < 0.05). Synbiotic supplementation had greater effects on intestinal microbiota and morphology than dietary β‐glucan alone. For example, β‐glu+Bs increased the number of intestinal lactic acid bacteria and decreased the number of Vibrio spp. (P < 0.05), and β‐glu+Pa increased the height of intestinal villi.  相似文献   

18.
The objective of this study was to evaluate the probiotic properties of lactic acid bacteria (LAB) strains isolated from digestive tract of white shrimp Litopenaeus vannamei. Eighteen LAB colonies were isolated and one bacterium was found capable of producing three extracellular enzymes (protease, cellulose and lipase) simultaneously and exhibited antagonistic activity against shrimp pathogens (Vibrio vulnificus, V. rotiferianus and V. campbellii). The putative probiotic strain AS13 was identified as Lactobacillus pentosus based on 16S rRNA sequencing. The L. vannamei were fed diet containing 0 (control), 106, 107 and 108 CFU g?1 bacterial cells of AS13 for 28 days. The results showed that supplementation of L. pentosus significantly improved the growth performance and feed utilization in the treated groups over the control. Similarly, digestive enzyme activities were elevated in the intestines of treated groups. Moreover, feeding of supplemented diets containing AS13 significantly reduced the mortality rate caused by pathogenic Vibrio species (V. vulnificus, V. rotiferianus and V. campbellii). Our results indicated L. pentosus AS13 addition at 107 CFU g?1 can effectively enhance the growth performance, feed utilization, digestive enzymes and disease resistance of L. vannamei in the laboratory condition.  相似文献   

19.
In recent years, more and more attentions have been paid to the development and application of probiotics in aquaculture, and viable probiotics have been extensively studied, while rare information was available about inactivated probiotics in aquaculture. Therefore, in this study, a feeding trial was designed to investigate the effect of dietary supplementation of heat‐inactivated probiotic Bacillus clausii DE5 on growth performance, immune response and key immune genes expression in head kidney and intestine in grouper Epinephelus coioides. Fish were fed for 60 days with control diet (C) and two experimental diets containing 1.0 × 108 CFU/g live (T1) and heat‐inactivated (T2) B. clausii DE5, respectively. The probiotic treatments did not affect the final weight, weight gain (WG) and specific growth rate (SGR) of E. coioides at days 30 and 60 (p > .05), while both heat‐inactivated and live B. clausii DE5 significantly decreased the feed intake and feed conversion ratio (FCR) at day 60 (p < .05). Serum lysozyme activity and complement C3 level in the two probiotic treatments were significantly higher than those in the control (p < .05). The lysozyme activity and complement C3 level at day 60 were significantly higher than those at day 30 (p < .05), while no significant interaction effect between diet and administration date was observed. Moreover, the heat‐inactivated B. clausii DE5 significantly improved the expression of TLR5, pro‐inflammatory cytokines (IL‐8 and IL‐1β) and TGF‐β1 in head kidney and intestine (p < .05), while the live probiotic did not show any significant effect on the expression of these key immune‐related genes in head kidney and intestine. These results indicate that dietary supplementation of heat‐inactivated B. clausii DE5 effectively improved feed utilization and both the local and systemic immune responses of E. coioides.  相似文献   

20.
This study was carried out to investigate the effect of water‐soluble polysaccharides extract of algae Ulva rigida (WPU) as dietary supplement on growth performance, antioxidant enzyme activity, lysozyme and phenoloxidase activity, and resistance of shrimp (Litopenaeus vannamei) subjected to bacterial infection with Photobacterium damselae. Three replicate groups of shrimp (1.0 g) were fed four diets containing four levels, 0 or control, 0.5, 1 and 1.5 g/kg of WPU for 8 weeks over the growth trial. Thereafter, 30 shrimps from each dietary treatment were infected with bacteria P. damselae to evaluate disease resistance of infected shrimp. The results of this study showed that WPU was effective as a growth promoter for L. vannamei. The best growth rate was observed in shrimp fed 1.5 g/kg of WPU diet. Regarding antioxidant defences, the diets supplemented with three levels of WPU stimulated glutathione peroxidase and catalase activates in experimental shrimps. MDA content of L. vannamei‐fed diet containing WPU 1.5 and WPU 1.0 was lower than WPU 0 and WPU 0. 5 diets. Also, lysozyme and phenoloxidase activities of shrimp receiving WPU at 1.0 and 1.5 level were significantly higher than those fed WPU 0 and WPU 0.5 diets. In addition, using WPU extract in all diets decreased mortality in L. vannamei in a dose‐dependent manner after challenge with P. damselae. These results suggest that incorporation of water‐soluble polysaccharides from green algae U. rigida at 1.5 g/kg doses improves growth and antioxidant activity and enhances the immune responses in shrimp L. vannamei.  相似文献   

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