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1.
A growth trial was conducted to evaluate the effects and safety of nucleotides in low fish meal diets on the growth performance, antioxidative capacity and intestinal morphology of turbot (Scophthalmus maximus). High fish meal control diet was formulated with 500 g kg?1 fish meal. Seven levels (0.075, 0.15, 0.225, 0.300, 1.5 and 3.0 g kg?1, respectively) of nucleotides were added to a low fish meal basal diet, which was formulated with 400 g kg?1 fish meal. The eight experimental diets were fed to groups of juvenile turbot (initial weight: 6.0 ± 0.03 g) for 60 days. Results showed that compared with high fish meal control diet, low fish meal basal diet treatment had lower total antioxidative capacity (T‐AOC), glutathione peroxidase activity, fold height of proximal and distal intestine, enterocyte height of all evaluated enteric section and microvillus height of mid‐intestine and distal intestine (P < 0.05). However, supplemented nucleotides in diets could significantly improve growth (specific growth rate, SGR), feed utilization, antioxidative capacity and intestinal morphology of turbot (P < 0.05). Broken‐line regression analysis of SGR and T‐AOC showed that the optimal supplemental levels of dietary nucleotide for juvenile turbot were 0.366 and 0.188 g kg?1, respectively. In summary, 0.300 g kg?1 of dietary nucleotides was helpful in improving growth, feed utilization, antioxidative capacity and intestinal morphology of turbot fed with low fish meal diet. Excessive dietary nucleotides (3.0 g kg?1) might cause oxidative stress and morphological damage in intestine and then reduce the growth of turbot.  相似文献   

2.
This study was conducted to evaluate the effects of dietary probiotic supplementation on growth performance, fish welfare, sensory evaluation, freshness during ice storage and changes in intestinal microbiota of rainbow trout (Oncorhynchus mykiss). The 9‐week feeding trial was conducted in cages under commercial conditions during the winter season, when water temperature decreased from 14°C to 7°C. Fish were fed either a diet without probiotic supplementation (control) or with 0.2% (2 × 109 CFU kg?1 diet) of multi‐strain probiotic bacteria (Bacillus sp., Pediococcus sp., Enterococcus sp., Lactobacillus sp.). Fish weight was recorded at 0, 2, 4, 6 and 9 weeks. Growth performance was not affected by dietary probiotic supplementation. Alternative complement activity (ACH50) was significantly higher in fish fed the diet with probiotic (58.4 ± 3.7 units mL?1) than in the control group (46.9 ± 3.1 units mL?1) (P = 0.03). Several biochemical markers were altered by the dietary treatment. 7‐ethoxyresorufin‐O‐deethylase (EROD) (P < 0.01), glutathione S‐transferase (GST) (P < 0.001), glutathione peroxidase (GPx) (P < 0.05) increased and lipid peroxidation (LP) (P < 0.01) decreased with dietary probiotic supplementation. Flesh quality and shelf‐life of fish stored on ice was not affected by dietary probiotic supplementation. Probiotic supplementation had a limited effect on the intestinal microbiota. Signal strength of the observed operational taxonomic units (OTUs) differed between the control and treatment samples and could indicate variations in the abundance of certain OTUs. Microbiota adhering to the intestinal mucus varied between sampling points, indicating that changes were associated with water temperature.  相似文献   

3.
To evaluate the possible dietary application of live and heat‐inactivated probiotic Bacillus pumilus SE5 in grouper Epinephelus coioides, juveniles (14.6 ± 0.2 g) were fed either a basal control diet (without probiotic) or the basal diet supplemented with 1.0 × 108 CFU g?1 live (T1) and heat‐inactivated B. pumilus SE5 (T2). The heat‐inactivated probiotic significantly improved the final weight, weight gain (WG) and specific growth rate (SGR) at day 60 and significantly decreased the feed conversion ratio (FCR) at day 30 and 60, while the viable probiotic significantly decreased the FCR at day 60 (P < 0.05). Phagocytic activity, serum complement C3 and IgM levels as well as SOD activity elevated significantly in fish fed the heat‐inactivated probiotic for 60 days (P < 0.05). Furthermore, the heat‐inactivated probiotic remarkably up‐regulated expression of TLR2 and pro‐inflammatory cytokines (IL‐8 and IL‐1β) in head kidney (P < 0.05), but the viable probiotic failed to do so. These results indicated that heat‐inactivated B. pumilus SE5 can effectively improve the growth performance and immune responses of E. coioides.  相似文献   

4.
An 8‐week‐feeding trial was conducted to investigate the effect of dietary chitosan oligosaccharide complex with rare earth (COS‐REE) on growth performance and innate immune response of turbot, Scophthalmus maximus L. (Initial average weight was (12.1 ± 0.1) g) as well as disease resistance against Edwardsiella tarda. Six practical diets (approximately 53.01% protein and 12.57% lipid) were formulated to contain graded levels (0, 75, 150, 300, 600 and 1200 mg kg?1) of COS‐REE. Results of the present study showed that, compared to the control group (0 mg kg?1), the specific growth rate (SGR) was significantly higher in fish fed the diet with 300 mg kg?1 COS‐REE (P < 0.05), while the feed conversion ratio (FCR) significantly decreased (P < 0.05). The phagocytic index (PI) and the activity of super oxide dismutase (SOD) of serum in fish fed the diet with 300 mg kg?1 COS‐REE was significantly higher than fish fed the control diet (P < 0.05), but no significant differences were observed in malondialdehyde (MDA) and hepatic metallothionein (MT) concentrations. After 8 weeks, fish were challenged by intraperitoneal injection with E. tarda, and COS‐REE‐treated fish demonstrated increased protection capability. These results suggested that COS‐REE could enhance growth, innate immunity and disease resistance in turbot, and the optimum dose was approximately 300 mg kg?1.  相似文献   

5.
A growth trial was conducted to evaluate the effects of chelated (Mintrex? Mn, Mn‐M) or inorganic (MnSO4·H2O, Mn‐S) manganese (Mn) on growth, feed utilization, tissue Mn deposition and liver superoxide dismutase (SOD) activity in turbot Scophthalmus maximus. A semi‐purified basal diet was formulated to be deficient in Mn (3.7 mg kg?1) and contained tricalcium phosphate and sodium phytate at levels of 20 and 5 g kg?1, respectively. Ten other diets were made by adding five levels (5, 10, 20, 35 and 55 mg Mn kg?1 diet) of either the Mn‐M or Mn‐S to the basal diet, respectively. The 11 experimental diets were fed to groups of turbot (mean initial weight: 4.6 g) for 8 weeks. Results showed that the specific growth rate (SGR), feed intake, whole body Mn/vertebra Mn concentration and Mn‐SOD activity in liver were significantly improved by Mn supplementation (P < 0.05). On the basis of SGR, vertebra Mn concentration or liver Mn‐SOD activity data, dietary Mn requirement was estimated to be 10.5, 46.3 or 12.9 mg kg?1 for turbot fed Mn‐S, and the same was estimated to be 7.6, 43.0 or 22.5 mg kg?1 for turbot fed Mn‐M, respectively. There was no significant difference in growth, feed intake, whole body Mn concentration or vertebra Mn concentration between the two dietary Mn sources (P > 0.05).  相似文献   

6.
Vibrio anguillarum is an aggressive and halophilic bacterial pathogen most commonly originating from seawater. Vibrio anguillarum presence in fisheries and aquaculture facilities causes significant morbidity and mortality among aquaculture species primarily from haemorrhaging of the body and skin of the infected fish that eventually leads to death, collectively recognized as the disease vibriosis. This study served to develop a non‐probe, multiplex real‐time PCR assay to rapidly detect V. anguillarum presence in seawater. Specific primers targeting genes vah1, empA and rpoN of V. anguillarum were selected for multiplex reaction among 11 different primer sets and the extension step was eliminated. Primer concentration, denaturation time as well as annealing time and temperature of DNA amplification were optimized, thus reducing reaction duration. The two‐step, non‐probed multiplex real‐time PCR set forth by this study detects as little as 3 CFU mL?1 of V. anguillarum presence in sea water, without enrichment cultivation, in 70 min with molecular precision and includes melting curve confirmation.  相似文献   

7.
A 12‐week growth trial was conducted in a flow‐through system to determine dietary selenium (Se) requirement for on‐growing gibel carp (initial body weight: 76.2 ± 0.05 g, mean ± SEM). Selenomethionine was supplemented to the basal diet to formulate seven semi‐purified diets containing 0.26, 0.58, 0.72, 1.14, 1.34, 1.73 and 2.09 mg Se kg?1 diet. The results showed that plasma superoxide dismutase (SOD) activity significantly increased when fish were fed with 0.58 mg Se kg?1 diet (P < 0.05) and then decreased at 2.09 mg Se kg?1 diet (P < 0.05). Plasma T‐AOC activity was higher in fish fed with 0.72 mg Se kg?1 diet (P < 0.05) and plasma malondialdehyde (MDA) was higher in fish fed with 0.26 mg Se kg?1 diet (P < 0.05). When fish were fed 1.14 mg Se kg?1 diet, hepatic GSH‐Px, T‐AOC, GSH and CAT activities were significantly higher than those fed with 0.26 mg Se kg?1 diet (P < 0.05). Hepatic superoxide dismutase (SOD) activity was higher at 1.34 mg Se kg?1 diet (P < 0.05). Fish liver Se concentrations were significantly higher when fed with 0.72 mg Se kg?1 diet (P < 0.05) and then kept constant when Se ≥ 0.72 mg kg?1 (P > 0.05). Whole‐body and muscle Se concentrations were higher when fed with 1.34 mg Se kg?1 diet (P < 0.05) and kept a plateau when Se ≥ 1.34 mg kg?1 (P > 0.05). In conclusion, based on broken‐line regression of hepatic Se concentrations, hepatic SOD activity and hepatic T‐AOC activity, dietary Se requirements for on‐growing gibel carp was 0.73 mg kg?1, 1.12 mg kg?1 and 1.19 mg kg?1 diet respectively.  相似文献   

8.
Fish are always susceptible to a wide variety of deadly pathogens which cause a huge loss in aquaculture industries. In this investigation, we have demonstrated the in vivo probiotic efficiency of Bacillus sp. MVF1 (GenBank Acc. No. KP256503) in Labeo rohita challenged with pathogenic strain of Aeromonas hydrophila (MTCC 1739). To check the probiotic potential of the selected bacterial strain, fish were divided into four groups: control, D1, D2 and D3. A total of 100 days (70 days probiotic feeding + 71th day sampling and 28 days challenged test + 29th day sampling) of feeding trial was conducted. To establish the probiotic potential of Bacillus sp. MVF1, certain haematological parameters (haemoglobin, total erythrocyte and leucocyte count), serum biochemical parameters (total protein, albumin and globulin), immune parameters (serum lysozyme and total IgM levels) and hepatic stress profile (malondialdehyde production, superoxide dismutase and catalase activity) have been measured. Our results demonstrated that red blood cell number, white blood cell number and haemoglobin content were much higher in D2 group fish compared to other groups and control fish. Similarly, total protein contents, albumin concentration, globulin concentration, lysozyme activity and IgM production were also recorded to be highest in D2 group fish. This finding clearly indicated the probiotic potential of Bacillus sp. MVF1 in L. rohita. Furthermore, our results also demonstrated that 1 × 107 CFU g?1 feed (D2) provides better immunity compared to 1 × 105 (D1) and 1 × 109 (D3). Due to beneficial effects, the bacterium Bacillus sp. MVF1 might be useful in aquaculture industries to reduce the disease susceptibility.  相似文献   

9.
This experiment was conducted to study the effect of dietary supplementation of probiotic on performance and intestinal microflora of Chinese soft‐shelled turtle. Healthy Chinese soft‐shelled turtles (6000 pieces with average weight of 5 g) were selected and randomly divided into two groups: control and treatment with three replicates each. The control was fed on normal basal diet, whereas treatment was fed on basal diet supplemented with 1 × 108 cfu.g?1 Bacillus subtilis preparation. The results showed that the final mean weight of treatment (265.84 ± 3.48 g) was significantly higher (P < 0.05) than that of control (240.45 ± 4.32 g). There was significant difference (P < 0.05) in FCR, and DGs were obtained in probiotics fed group as compared to control. The level of sucrase, maltase, amylase, lipase and ATPase of treatment was significantly higher (P < 0.05) than that of control. Pyrosequencing showed that the dietary supplementation of probiotic Bacillus strain decreased microbial diversity. Phylum Firmicutes was dominant in both groups. Compared with the control, Firmicutes was increased, while others were decreased in treatment group. The results indicated that dietary supplementation of probiotic can improve growth performance, digestibility and intestinal microflora in Chinese soft‐shelled turtle.  相似文献   

10.
Four isolates obtained from gilthead seabream have been tested for their adhesion to the skin, gill and intestinal mucus of gilthead seabream, and for their ability to interfere with Listonella anguillarum, an important pathogen of farmed gilthead seabream. The ability to adhere to mucus was higher than 7% for all isolates. Three isolates showed an antagonistic effect against some of the pathogenic strains tested. They were assayed to interfere with the attachment of L. anguillarum to the mucus of gilthead seabream. Only two isolates significantly reduced the adhesion of L. anguillarum to all of the mucus assayed under exclusion, competition and displacement conditions. According to the criteria applied, the isolate Pdp11 was selected and its in vivo probiotic potential was assessed by oral administration followed by challenge with the pathogen L. anguillarum. For the feeding trial, a group of 50 gilthead seabreams received a commercial diet supplemented with lyophilized 108 CFU g?1 of this isolate for 15 days. An other group of similar characteristics received the non‐supplemented commercial diet. After the challenge, the mortality of the fish receiving the diet supplemented with the potential probiotic was significantly lower than that observed in the groups of fish receiving the non‐supplemented commercial diet.  相似文献   

11.
Vibrio anguillarum, which is part of normal microflora on fish, is the causative agent of vibriosis in aquaculture. It is speculated that V. anguillarum does not affect the host in most situations, but can cause a severe disease once the host is compromised. In the study reported herein, skin‐injured and intestine‐injured zebrafish, Danio rerio, were established as a model to mimic the natural infection caused by V. anguillarum when fish suffered an injury to a mucosal surface. Our results showed the lethal dose to 50% of the population (LD50) of skin‐injured zebrafish was 6.8 × 103 colony‐forming unit (CFU)/mL, which was much lower than intestine‐injured zebrafish (1.9 × 106 CFU/mL) or non‐injured zebrafish (5.5 × 106 CFU/mL). With the quantitative polymerase chain reaction and immunohistochemical analysis, we found that V. anguillarum proliferated rapidly in the skin and muscle after the bacteria entered into the host via the skin injury. The bacteria were subsequently transported to the immune organs and then caused a systemic infection in the fish. However, mortality of skin‐injured zebrafish significantly decreased if the fish were allowed to heal. These results indicate that minimizing injury to the mucosal surfaces of fish, especially the skin, will reduce infections caused by V. anguillarum.  相似文献   

12.
In bivalve aquaculture, selecting suitable probiotic treatments can be crucial for improving hatchery‐rearing of larvae and juveniles. We assessed the potential of five bacterial strains, previously selected in vitro, to improve survival, growth and resistance of catarina scallop Argopecten ventricosus during early and late larval and juvenile developmental stages, as well as during exposure to the pathogen Vibrio alginolyticus. Hatchery‐reared larvae and juveniles were treated with eight treatments of single or combined strains of Bacillus and Lactobacillus at 1 × 106 CFU mL?1 every 48 h for 9 days (larvae) and 21 days (juveniles). Compared with the control, significantly higher survival and growth in size and weight of early veliger larvae occurred with the antibiotic and the RL5 (Lactobacillus graminis) treatments. Significantly enhanced settlement of pediveliger larvae occurred with a different probiotic strain, the mix of Lactobacillus and Bacillus (MIX‐LB), while higher survival and growth of early juveniles occurred with C3 (Lactobacillus plantarum). The mix of Bacillus (MIX‐B) significantly increased survival of juveniles from V. alginolyticus after 120‐h infection, consistent with maximum activity of superoxide dismutase enzyme. In contrast, all untreated and infected scallops died by 96 h. The three Bacillus strains performed poorly when used as single treatments and when given to early developing larvae. Our results indicate that the action mechanism of probiotic strains is stage specific and strain specific, generating different responses by the host, including improved survival and growth (likely from better nutrient assimilation) and higher resistance against pathogens (possibly from strengthening the immune system).  相似文献   

13.
Four alkaloids (Sanguinarine, 6‐Methoxyl‐dihydro‐chelerythrine, Cryptopine and β‐Allocryptopine) were isolated from aerial parts of Macleaya microcarpa (Maxim) Fedde using bioassay‐guided isolation method, and the inhibitory activity of ethanolic extract, various fractions and these four alkaloids against four fish pathogenic bacteria (Aeromonas hydrophila, Aeromonas salmonicida, Vibrio anguillarum and Vibrio harveyi) was assessed in vitro using the agar dilution method and the microdilution assay method respectively. A. hydrophila was the most sensitive strain to all the tested compounds. Minimum inhibitory concentration (MIC) values were lower for sanguinarine against all tested Gram‐negative strains than other three alkaloids, with MIC values of 12.5 mg L?1 for A. hydrophila and 50 mg L?1 to other pathogenic bacteria. Followed by 6‐methoxyl‐dihydro‐chelerythrine, which showed considerable antibacterial activity with MIC values of 80 mg L?1 for A. hydrophila, 100 mg L?1 for V. harveyi, and 125 mg L?1 for both V. anguillarum and A. salmonicida. Cryptopine and β‐allocryptopine revealed similar inhibitory activity with MIC values of 100 mg L?1 for A. hydrophila and 200 mg L?1 for other three bacterial species. These finding provided evidence that extract, as well as isolated compounds from M. microcarpa might be potential sources novel antibacterial agents for the treatment of fish infectious diseases.  相似文献   

14.
The aim of this study was to determine whether orally administered V. anguillarum cells could survive passage through the intestinal tract of feeding turbot, and thereafter, proliferate in the released faeces. In addition, the growth of the pathogen in turbot faeces in the presence of a Carnobacterium sp. with inhibitory effects against a number of bacterial fish pathogens was studied. It was found that V. anguillarum cells survived the acidic environment of the stomach for several hours, persisted in the intestine and readily proliferated in the released faeces. The antagonistic Carnobacterium sp. inhibited the growth of V. anguillarum during co-culture in turbot faecal extracts. From the results, it was concluded that the turbot intestinal tract and faeces can serve as an enrichment site for V. anguillarum, and the use of intestinal bacteria with antagonistic activity against vibrios may be used to reduce the load of fish pathogenic vibrios in turbot hatcheries.  相似文献   

15.
In aquaculture, exposure to stressful conditions and problems related to diseases often occur resulting in serious economic loss. The use of probiotics that control pathogens through different mechanisms, aiding digestion by exoenzyme supply and establishment of beneficial microflora in the digestive tract has got increased attention recently. Two different bacterial species Micrococcus MCCB 104 and Bacillus MCCB 101 were tested as probiotics for two cichlid species Etroplus suratensis and Oreochromis mossambicus. The strains were administered separately and together, at a rate of 103 CFU animal?1 day?1 for 28 days. The effects on digestive enzyme activity and growth were compared with those fed on control diet. FCR of E. suratensis was high in case of Bacillus alone as well as the mixed culture (Micrococcus and Bacillus together) than that of control. However, the SGR of E. suratensis was slightly lower than that of control during 14 days trial. SGR of both the treatments (Bacillus alone and mixed culture) was higher than that of the control on 28th day, and this might be due to the reason that specific duration is needed for the assimilation and conversion of nutrients into proteins. The intestinal digestive hydrolases of E. suratensis were profoundly enhanced mainly by Bacillus and mixed cultures. The hepatopancreatic versions of major digestive enzymes in E. suratensis were influenced variously by different probiotic treatments. The alpha‐amylase activity of hepatopancreas has been elevated significantly by mixed culture during 14 days experiments while on 28 days trials both Bacillus and mixed culture showed an enhancing effect. During 14 days feeding trials, the intestinal lipase activity has been prominently enhanced by all probiotic treatments. It is found that, in O. mossambicus, both 14 days and 28 days feeding experiments, the pepsin as well as intestinal digestive enzymes such as amylase, total alkaline protease, lipase and their hepatopancreatic counter parts showed a significant elevation in their specific activity. Intestinal alpha‐amylase and total alkaline proteases of O. mossambicus showed an increase in specific activities on both 14 days and 28 days feeding experiments with the Bacillus and Micrococcus combination. The hepatopancreatic enzymes were highly influenced by the Bacillus species in O. mossambicus. The results of this study suggest that live probiotic microorganisms such as Micrococcus MCCB 104 and Bacillus MCCB 101 may be incorporated while formulating the cost‐effective, nutritionally balanced diet of E. suratensis and O. mossambicus for better growth performance and nutrient utilization.  相似文献   

16.
This study was performed to evaluate the effect of dietary chitosan on haematology, innate immunity and protection against Vibrio anguillarum in Asian seabass, Lates calcarifer. A basal diet supplemented with 0, 5, 10 and 20 g chitosan kg?1 diet was fed to the four different groups for 60 days. The haematological (total erythrocyte count, total leucocyte count, total serum protein, albumin, globulin and albumin‐globulin ratio) and innate immune parameters (phagocytic ratio, respiratory burst, serum lysozyme and serum bactericidal activities) were monitored at fortnight interval to assess the effect of chitosan feeding in Asian seabass. All the studied haematological and innate immune parameters were increased significantly (P ≤ 0.05) in chitosan‐fed groups in comparison with control. However, the group fed diet containing 10 g chitosan Kg?1 feed showed highest haematological and innate immune parameters on 45th day in comparison with other groups. Moreover, the fish fed the diet containing 10 g chitosan Kg?1 feed had significantly higher post‐challenge survival (75.56 ± 4.44%) on the 30th day following V. anguillarum challenge. Therefore, this study suggests that chitosan at 10 g kg?1 diet could be used as prophylactic in Asian seabass culture to enhance the protection against any possible infection by V. anguillarum.  相似文献   

17.
Fish meal, vitamin C and fish oil are known to play essential roles in reproduction and immunity in animals. To investigate how the diet affect reproduction under the condition of reducing costs, we designed an experimental diet that decreased the ratio of fish meal with soybean meal from 1:1 to 1:1.5, and supplemented with 0.06% vitamin C and 3.8% fish oil for the crayfish, Procambarus clarkii. After a 100‐day feeding experiment, female crayfish fed the test diet had significantly greater gonadosomatic index (GSI) compared with those fed the basal diet (P < 0.05). At the middle stage of ovarian development, the test diet gave significantly higher trypsin‐specific activity (340.94 ± 57.32 U mg?1 protein) in hepatopancreas of the crayfish than the basal diet (89.48 ± 10.01 U mg?1 protein) (P < 0.05). However, hepatosomatic index (HSI) was remarkably decreased for those females fed test diet (P < 0.05). In addition, the experimental diet resulted in markedly lower superoxide dismutase (SOD) activity and malonaldehyde (MDA) levels, especially in the ovaries (P < 0.01). These results suggest that dietary reduction of fish meal, supplementation of appropriate amounts of vitamin C and fish oil may promote ovary development probably by increasing digestibility, as well as by promoting transferring of nutrients from hepatopancreas to ovary and raising immunity of P. clarkii.  相似文献   

18.
The effects of dietary mannan oligosaccharides (MOS; 4 g kg?1; Bio‐Mos, Alltech Inc, USA) in diets for European sea bass, Dicentrarchus labrax (L.), juveniles in relation to disease and stress resistance, combining intestinal infection with Vibrio anguillarum and stress challenge by confinement, were assessed in this study. After 8 weeks of MOS supplementation, fish were exposed to a pathogen challenge test against V. anguillarum by direct gut inoculation combined with a confinement stressor panel. Cumulative mortality of fish fed MOS caused by anally inoculated V. anguillarum decreased from 66% to 12.5% and from 54.1% to 25% in infected and infected + stressed fish, respectively, compared to fish fed control diet. Results for European sea bass revealed a positive effect of MOS dietary inclusion on disease resistance, in terms of cumulative mortality, against gut inoculated V. anguillarum, as well as reduced effects of stress on microbiota diversity. Both of these findings, together with the enhanced innate immune response and the higher gut mucus production and density of eosinophil granulocytes in gut mucosa obtained in previous studies after MOS supplementation ( Torrecillas et al. 2007, 2011a,b ) suggest that general reinforcement of the innate immune system, and particularly of the intestinal barrier efficiency, is the main defence mechanism of European sea bass fed MOS against pathogenic microorganisms.  相似文献   

19.
This study investigated the effects of valine on growth, intestinal enzyme activities and microflora in juvenile Jian carp (Cyprinus carpio var. Jian). A total of 1200 fish with an average initial weight of 9.67 ± 0.03 g were fed diets containing 5.3 (unsupplemented control), 8.7, 11.8, 14.9, 18.7 and 20.1 g valine kg?1 diet for 60 days. Results indicated that the specific growth rate, feed efficiency, body protein and lipid content of fish were significantly improved by the dietary valine (P < 0.05). The hepatopancreas weight and activities of trypsin, amylase, lipase, chymotrypsin, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) took the similar trends. Similarly, the optimum levels of dietary valine induced increases in the intestinal length, weight, folds height and activities of alkaline phosphatase, gamma‐glutamyl transpeptidase and creatine kinase. In contrast, the trends of muscle GOT activity and plasma ammonia content were opposite. Intestinal Aeromonas, Escherichia coli, Lactobacillus and Bacillus were changed by dietary valine supplementations. The dietary valine requirement for Jian carp (9.67–76.4 g) based on SGR was 13.7 g valine kg?1 diet (4.0 g valine 100 g?1 CP). Together, these results indicated that valine improved fish growth, digestive and absorptive ability.  相似文献   

20.
Pollution by the heavy metal lead (Pb) has become a threat to both aquaculture and food safety. In this study, the protective effects of a selected probiotic with good Pb binding capacity (Lactobacillus plantarumCCFM8661) against waterborne Pb exposure were evaluated in Nile tilapia (Oreochromis niloticus). One hundred and eighty fish were divided into four groups as control, Pb‐only, Pb‐plus‐CCFM8661 and CCFM8661‐only. Fish were exposed to a dose of waterborne Pb level at 1 mg L?1 for 4 weeks, and the probiotic was administered at 108 CFU g?1 in fish diet twice daily. The results showed that dietary supplementation of CCFM8661 ameliorated the growth performance and prevented the death of Pb‐exposed fish. Cotreatment with Pb and CCFM8661 also effectively decreased Pb accumulation in kidney, liver, gonad, brain, gills and muscle. Moreover, the administration of this probiotic alleviated Pb‐induced oxidative stress, recovered digestive enzyme activities and blood δ‐aminolevulinic acid dehydratase activity, reversed alterations in innate immune status and decreased the frequencies of the nuclear abnormalities in peripheral blood erythrocytes of fish. These results suggested that CCFM8661 may be a novel dietary supplement against Pb toxicity at least in tilapia.  相似文献   

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