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1.
The objective of this study was conducted to research the effects of β‐conglycinin in the diets on the growth performance, immunity function, antioxidant capacity and intestinal health of juvenile golden crucian carp (Carassius auratus). Five diets contained respectively (0, 20, 40, 60 and 80 g/kg) β‐conglycinin, and were used to feed juvenile golden crucian carp for 56 days. Final weight, weight gain and specific growth rate were significantly reduced by dietary β‐conglycinin (20–80 g/kg). Feed efficiency and protein efficiency were significantly reduced by dietary β‐conglycinin (40–80 g/kg). In hepatopancreas, the activities of T‐SOD, ACP, ALT and T‐AOC were significantly suppressed by dietary β‐conglycinin (20–80 g/kg). The activities of LZM, AKP, CAT and GPx were significantly reduced by dietary β‐conglycinin (40–80 g/kg). The activities of protease were significantly reduced and the content of MDA was significantly increased by dietary β‐conglycinin (60–80 g/kg). In proximal intestines, the activities of protease and CAT were significantly decreased by dietary β‐conglycinin (40–80 g/kg). In mid and distal intestines, the activities of protease and CAT were significantly inhibited by dietary β‐conglycinin (20–80 g/kg). In intestines, T‐AOC and GPx were significantly declined by dietary β‐conglycinin (20–80 g/kg). In proximal and mid intestines, the content of MDA were significantly increased by dietary β‐conglycinin (40–80 g/kg). In distal intestines, the content of MDA was significantly increased by dietary β‐conglycinin (20–80 g/kg). The expression of IGF‐I was significantly decreased and the expression of IL‐1β and TNF‐α was significantly increased by dietary β‐conglycinin (20–80 g/kg). The structural integrity of intestinal tissues were damaged by dietary β‐conglycinin (20–80 g/kg), the part of intestinal villus were shed, the part of epithelial cells were separated from lamina propria. Ultimately, these results suggested dietary β‐conglycinin should be <20 g/kg in formula feed of golden crucian carp.  相似文献   

2.
This study was conducted to investigate the effects of dietary β‐conglycinin on the growth performance, digestion, gut morphology and immune responses of juvenile turbot (Scophthalmus maximus L.). Four diets were formulated to contain 0%, 2%, 4% and 8% purified β‐conglycinin. Triplicate groups of 30 fish were fed to apparent satiation twice daily for 12 weeks. Fish fed 4% and 8% dietary β‐conglycinin showed significantly reduced specific growth rate, feed efficiency ratio, apparent digestibility coefficient of nutrients and whole‐body lipid contents, as well as a profound infiltration of mixed leucocytes in the lamina propria and a significant decrease in the absorptive surface of distal intestine. The expression of pro‐inflammatory cytokines, TNF‐α and IL‐1β, in the distal intestine was significantly upregulated by 4% dietary β‐conglycinin, whereas a significantly lower expression level of IgM and anti‐inflammatory cytokine TGF‐β1 was observed in fish fed 8% dietary β‐conglycinin. Serum lysozyme and alternative complement pathway activity were first significantly enhanced by 2% dietary β‐conglycinin and then rapidly declined by 4% and 8% dietary β‐conglycinin. Respiratory burst activity of head kidney macrophages and serum superoxide dismutase activity were significantly suppressed by 4% and 8% dietary β‐conglycinin. Dietary β‐conglycinin (2–8%) significantly increased the level of specific antibody against β‐conglycinin in serum. Collectively, these results suggested that higher levels of dietary β‐conglycinin (4–8%) induced a variety of non‐specific and specific immune responses and intestinal mucosal lesions in turbot, resulting in inferior feed utilization and poor growth performance.  相似文献   

3.
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   

4.
p38 is an important component of the MAPK signaling pathways as a Ser/Thr protein kinase. We cloned the full length p38 (Es‐p38) cDNA sequence in Eriocheir Sinensis which contained a 1098‐nucleotide ORF that encoded a protein of 365 amino acids. Es‐p38 protein has a p38 MAPK functional domain (STKc_p38), it is a typical serine/threonine kinase and processes all p38 protein's conservative T‐G‐Y motif. Tissue expression of the Es‐p38 gene and expression during testis development stages were determined by quantitative real‐time PCR analysis. The results show that Es‐p38 gene is expressed in various tissues, but it expresses higher in the muscle, hepatopancreas, intestine, ovary and testis. The expression level of Es‐p38 gene at different stages of testis development shows no significant difference between the spermatocyte phase (July–August) and spermatid stage (August–October), but it rises significantly in the mid‐late period of sperm stage (December–January). This changing trend has a positive relationship with the E. Sinensis gonad development and reproduction stage, which preliminarily shows that Es‐p38 may function in the E. Sinensis testis development and the process of spermatogenesis.  相似文献   

5.
A 4‐week growth trial was conducted to compare the effects of different feeding strategies of dietary immunostimulants on the growth, immunity and resistance against Vibrio splendidus of sea cucumbers Apostichopus japonicus (Selenka). Six feeding strategies were set, including feeding immunostimulants‐free diet continuously (control), feeding dietary β‐glucan (1.25 g kg?1 diet) continuously, feeding dietary mannan‐oligosaccharides (MOS; 2.00 g kg?1 diet) continuously, feeding β‐glucan 2 days followed by MOS 5 days alternately, feeding β‐glucan 5 days followed by MOS 2 days alternately and feeding β‐glucan 7 days followed by MOS 7 days alternately. The sea cucumbers fed immunostimulants showed higher specific growth rate (SGR) and lower cumulative mortality than control (P < 0.05). When sea cucumbers were fed with β‐glucan continuously, total coelomocytes counts and superoxide anion were significantly higher than control on the 4th day (P < 0.05). However, these two immune parameters were not significantly higher than those in control after the 18th day (P > 0.05). While sea cucumbers continuously fed MOS, these two immune parameters were not significantly higher than control until the 15th day. All immune parameters of the sea cucumbers fed with β‐glucan and MOS alternately were significantly higher than those in control during the experiment (P < 0.05). The sea cucumbers fed with β‐glucan 7 days followed MOS 7 days alternately showed the highest SGR and second lowest cumulative mortality. It was suggested that this feeding strategy is most suitable for sea cucumbers.  相似文献   

6.
The effect of dietary β‐glucan on the bacterial community in the gut of common carp (Cyprinus carpio) was examined after oral application of Aeromonas hydrophila. Carp received either feed supplemented with 1% MacroGard®, a β‐1,3/1,6‐glucan, or a β‐glucan‐free diet. Fourteen days after feeding, half of the carp from each group were intubated with 109 colony‐forming units (CFU) of a pathogenic strain of A. hydrophila. Gut samples were taken 12 hr to 7 days after application and analysed using microbiological and molecular biological techniques (NGS, RT‐PCR‐DGGE). The reaction of the mucosa and the microbiota to an A. hydrophila intubation differed in carp fed with β‐glucan compared to carp from the control group. In β‐glucan fed carp, the total bacterial amount was lower but the number of bacterial species was higher. Bacterial composition was different for carp from both treatment groups. The number of mucin filled goblet cells was reduced in carp fed the β‐glucan diet. Mucus was obviously released from the goblet cells and was probably washed out of the gut together with high numbers of bacteria. This might be protective against pathogenic bacteria and, therefore, feeding with β‐glucan may provide protection against infections of the gut in carp.  相似文献   

7.
This study aimed to identify and characterize the cellular and metabolic response in vital organs of Dicentrarchus labrax, after feeding on soy‐based diets enriched with different taurine concentrations (T0.2, T0.5, T1.0 w/w). Molecular responses (expression of Hsp70, Hsp90, phosphorylation of p38 mitogen‐activated protein kinase‐p38MAPK and extracellular signal‐regulated kinases‐ERK1/2) were addressed. Metabolic and antioxidant capacities such as activities of citrate synthase (CS), malate and lactate dehydrogenase (MDH, L‐LDH), superoxide dismutase (SOD), catalase (CAT) and levels of thiobarbituric acid‐reactive substances (TBARS) were assessed. The most intense changes were detected in the liver and in the anterior intestine showing that taurine induces important protective biochemical mechanisms. Specifically, in the liver and the anterior intestine, Hsp and MAPK levels, as well as L‐LDH activity levels were up‐regulated under the effect of taurine diets. T diet had no major effect on the activity levels of CS, SOD and TBARS, except for MDH in the liver and catalase in the anterior intestine, where activity levels of these enzymes were increased under the effect of T0.2 and T1.0, respectively. These results may facilitate monitoring of adequate health status of farmed fish, exploiting the beneficial T effects and could assist at the formulation of aquaculture feeding strategies.  相似文献   

8.
The aim of this study was to evaluate the effects of dietary lipids on protein‐sparing and lipoprotein lipase (LPL) mRNA expression in culture using 360 juvenile soft‐shelled turtles (Pelodiscussinensis) (initial weight 4.26 ± 0.14 g). The turtles were allotted to six diets with three duplicates for 60 days. A control diet with 46% protein and 55% fishmeal (CD) and five isonitrogenous diets with 41.3% protein and 45% fishmeal (F, S, L1, L2 and L3) were used, containing the following three lipid types: fish oil, soybean oil and mixed oils (soybean oil: fish oil = 1:1). The results showed that the survival rate was not affected by dietary lipids (P > 0.05). The highest weight gain and lowest feed coefficient ratio were seen in the L3 diets (P < 0.05). Turtles fed with L2 and L3 diets had lower superoxide dismutase activities, higher alanine aminotransferase activities and higher cholesterol concentrations than those exposed to other diets (P < 0.05). Hepatic LPL activity and LPL mRNA expression were higher in the L3 diets than in the other diets (P < 0.05). Overall, there were obvious protein‐sparing effects of dietary lipids and LPL mRNA expression was stimulated by high dietary lipids in soft‐shelled turtles in this study.  相似文献   

9.
This study was carried out to investigate the effects of dietary pyridoxine (PN) on the antioxidant status, apoptosis, intercellular integrity and immune function of head kidney and spleen in young grass carp (Ctenopharyngodon idella). Results showed that compared with the optimal PN level, (a) PN deficiency decreased antioxidant enzyme activities and down‐regulated the mRNA levels of antioxidant enzymes, NF‐E2‐related factor 2 (Nrf2), myeloid cell leukaemia‐1 (Mcl‐1) and tight junction proteins, whereas it increased the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and protein carbonyl (PC), and up‐regulated the mRNA levels of cysteinyl aspartic acid‐protease (caspase), Fas ligand (FasL), p38 mitogen‐activated protein kinase (p38MAPK) and myosin light chain kinase (MLCK) in the head kidney and spleen of fish (p < .05). (b) PN deficiency decreased lysozyme (LZ) and acid phosphatase (ACP) activities, and complement contents, and down‐regulated the mRNA levels of antibacterial peptides, anti‐inflammatory cytokines, inhibitor of κBα (IκBα) and target of rapamycin (TOR), whereas it up‐regulated the mRNA levels of pro‐inflammatory cytokines and nuclear factor kappa B p65 (NF‐κBp65) in the head kidney and spleen of fish (p < .05). (c) Dietary PN requirements of grass carp based on the malondialdehyde content and lysozyme activity were estimated as 4.97 and 4.99 mg/kg diet, respectively.  相似文献   

10.
Six isonitrogenous and isoenergetic purified diets were formulated to feed Songpu mirror carp for 60 days. The control diet (CD) was only supplemented with soybean oil. The other five experimental diets contained soybean oil, linseed oil and lard oil blended at various inclusion levels to attain different linoleic acid (LA)/α‐linolenic acid (LNA) ratios (0.53, 1.04, 2.09, 3.95, 6.82) with a constant total C18 polyunsaturated fatty acids (PUFA; LA+LNA, 2% dry weight) content. The fatty acid (FA) profiles of hepatopancreas, dorsal muscle, intestine, intraperitoneal fat (IPF), spleen and kidney reflected those of the diets, but with some differences. The spleen showed the lowest correlation with diet compared with other tissues, followed by the hepatopancreas (P < 0.05). The intestine and IPF showed relatively higher correlation. On the other hand, the control group had the lowest tissue‐diet correlation, followed by the LA/LNA0.53 group (P < 0.05), whereas the LA/LNA2.09 showed the highest. The LA/LNA ratios in the tissues were up‐regulated in the LA/LNA0.53, 1.04 groups and down‐regulated in the LA/LNA3.95, 6.82 groups. This was due to when LA (or LNA) was highly added in diet, the decrease in this FA was huge in tissue. The contents of saturated fatty acids and monounsaturated fatty acids increased in the control group, but seemed not influenced by dietary LA/LNA ratios. These results demonstrated that the FA deposition was tissue‐specific, and also influenced by the dietary FA composition in the experimental fish. Finally, we suggest that 2.09 is the optimal LA/LNA ratio (2% C18 PUFA) of Songpu mirror carp for fillet FA composition.  相似文献   

11.
β‐1,3‐Glucan with 1.0 g kg?1 was supplemented to a basal diet [control (C)] with different feeding schedules: permanently β‐1,3‐glucan diet (BG) and 14 days BG–14 days control diet (C + BG). Growth and immunological responses [respiratory burst (RB), superoxide dismutase (SOD), catalase (CAT), lysozyme and total protein] in haemolymph, hepatopancreas and muscle of Litopenaeus vannamei were recorded after 84‐day feeding and exposure to nitrite‐N (20 mg L?1) for 120 h. β‐1,3‐Glucan administration did not affect growth performance. However, as compared with control, elevated CAT and lysozyme activities were seen in haemolymph of both BG groups, while significantly higher activities of SOD, lysozyme and RB in hepatopancreas, and higher activities of CAT and lysozyme in muscle were only seen in C + BG group. After nitrite‐N stress, significantly higher haemolymph protein, and hepatopancreas activities of lysozyme and RB were observed in both BG groups, but significantly higher activities of haemolymph SOD was only seen in C + BG group. The mortality in groups BG and C + BG was significantly lower than that in group C, but C + BG group showed a trend of higher nitrite‐N resistance compared with BG group. Considering dietary cost and immunostimulatory effects, the feeding schedule with 14 days BG–14 days control diet is more recommended.  相似文献   

12.
To explore the role of β‐glucan (0, 0.05%, 0.1% and 0.2%) in resisting bacteria, rainbow trout (Oncorhynchus mykiss) was challenged with Aeromonas salmonicida after 42‐day β‐glucan administration, and then sampled at 0, 2, 4 and 6 days post infection (dpi). The data showed that 0.2% β‐glucan reduced the accumulated mortality rates compared with the ICG (infected control group) (p < .05). The white blood cells, red blood cells and haemoglobin were higher in the 0.2% β‐glucan group (BG) than the ICG (p < .05). 0.1% and 0.2% β‐glucan elevated serum total antioxidative capability and glutathione activity but alleviated the increase of serum alkaline phosphatase activity and glucose concentration (p < .05) during infection. Serum TNF‐α, IL‐1β, IL‐8 and IgM in three BGs elevated remarkably on 6 dpi compared with the ICG (p < .05). Expression of tnf, il1b and cxcl8 of the head kidney in the 0.1% and 0.2% BGs was higher than the ICG on 4 dpi while ighm expression in the 0.2% BG was higher than in the ICG on 2 and 6 dpi (p < .05). 0.1% and 0.2% β‐glucan increased the expression of tlr5m, tlr5s, tmek and myd88 in the spleen after infection (p < .05). Similarly, 0.2% β‐glucan up‐regulated the expression of tmek, myd88, oncmyk‐dab and c3 in head kidney (p < .05). Overall, 0.2% dietary β‐glucan effectively decreased accumulated mortality rate by modulating the biochemistry process, cytokines, and activating TLR and ERK signalling pathways during A. salmonicida infection.  相似文献   

13.
A feeding trial was conducted to evaluate the effect of dietary β‐carotene level on the growth and liver vitamin A concentrations in soft‐shelled turtles, Pelodiscus sinensis, fed a vitamin A‐free diet. Soft‐shelled turtles were fed diets containing 0, 14.5, 26.5, 47.5, 87.3, 112.8 and 163.8 mg β‐carotene kg?1 for 10 weeks. Although it was not statistically significant due to high deviation within each group, mean weight gain of soft‐shelled turtles fed the diet without β‐carotene supplementation was the lowest among all test groups. Vitamin A concentrations in liver of turtles significantly (P<0.05) increased when dietary β‐carotene level reached 47.5 mg kg?1 indicating that soft‐shelled turtles were capable of converting β‐carotene to vitamin A. Analysed by regression modelling, dietary β‐carotene levels for optimal growth and maximal liver vitamin A contents of juvenile soft‐shelled turtles fed the vitamin A‐free diets were 49.1 and 88.7 mg kg?1 respectively.  相似文献   

14.
The potential of Bacillus subtilis E20‐fermented soybean meal (FSBM) as a partial alternative component of fish meal (FM) in fed diets of orange‐spotted grouper (Epinephelus coioides) was evaluated in this study. An FM‐based diet and seven diets containing 10%, 20% and 30% and 10%, 20%, 30% and 40% of FM replaced by soybean meal (SBM) and FSBM, respectively, were fed to grouper for 84 days to evaluate possible substitution levels of FM by tracking growth performance, digestive enzyme activity and morphological changes in the liver and distal intestine. No significant differences in survival and muscle composition of grouper were found between controls and treatments. Growth performance and feed efficiency of fish fed diets with FM replaced by FSBM up to 30% were not significantly different from controls, whereas significantly decreased growth performance and feed efficiency occurred with diets containing >20% of SBM. Based on the feed efficiency, the maximum substituted levels of FM by SBM and FSBM in grouper diets were 18.36% and 29.32%, respectively, based on broken‐line analyses. Histopathological changes in the liver and distal intestine, and significantly lower activity levels of digestive enzymes, including pepsin in the stomach and trypsin, chymotrypsin, amylase and lipase in the distal intestine, were found in fish fed a diet containing 30% of FM replaced by SBM. However, these parameters were improved by the substitution of FSBM. It is therefore believed that FSBM has great potential to be used as a protein source in grouper diets in partial replacement of FM.  相似文献   

15.
β‐glucan binding protein (βGBP), a pattern recognition protein was purified from the haemolymph of freshwater prawn Macrobrachium rosenbergii by heparin affinity chromatography that showed a single band in native gradient PAGE. The β‐glucan binding property of the purified protein was confirmed in a phenoloxidase (PO) assay, where addition of βGBP along with β‐glucan increased the specific PO activity compared with that of β‐glucan alone. The molecular weight of the βGBP was found to be ~316 kDa on gel filtration chromatography. In SDS‐PAGE, βGBP molecule was reduced to one polypeptide chain of molecular weight ~113 kDa. Thus the βGBP in M. rosenbergii is possibly a homotrimeric molecule. The purified sample run on unreduced condition in SDS‐PAGE also revealed a similar size band (~113 kDa) and hence, the polypeptide chains of βGBP are held by non‐covalent interactions. The purified βGBP samples run in native PAGE was stained positively with alcian blue for carbohydrates and Sudan black for lipids indicating the βGBP to be a glycolipoprotein. With rabbit polyclonal anti‐βGBP serum developed, an indirect ELISA was standardized and the normal βGBP concentration in adult M. rosenbergii serum was quantified to be ~2 mg mL?1. Furthermore, the applicability of the developed ELISA is discussed.  相似文献   

16.
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17.
Effects of Bacillus cereus BC‐01, Lactobacillus acidophilus LAG01, Clostridium butyricum CBG01 and their combinations as supplementation on the growth performance, digestive enzyme activities and serum non‐specific immunity of hybrid grouper (Epinephelus lanceolatus ♂×E. fuscoguttatus ♀) were assessed. Seven different diets, that is one control diet (basal feed without any probiotics, CT) and six treatment diets containing single B. cereus (Bs), L. acidophilus (Ls) and C. butyricum (Cs) at 1.0 × 109 cfu/kg feed, and also their combinations in equal proportion at 1.0, 2.0 and 3.0 × 109 cfu/kg feed (BLC1, BLC2 and BLC3) were prepared respectively. After 60‐day feeding trial, the final weight, specific growth rate,food consumption, food conversion efficiency and apparent digestibility coefficient of fish in Ls and BLC3 were significantly higher compared with the control (p < .05). The activities of pepsin and trypsin in the intestine of fish for Ls and BLC3 were significantly higher relative to the control (p < .05). Relative to controls, significantly enhanced amylase and lipase activities in proximal intestine except for Cs and BLC1 and lipase activities in distal intestine except for Cs were observed (p < .05). Meanwhile, activities of superoxide dismutase in the serum of fish for all treatments, lysozyme and catalase in Ls and BLC3, and glutathione peroxidase except for Cs were significantly enhanced (p < .05). Based on the above, dietary supplementation of single L. acidophilus at 1.0 × 109 cfu/kg or combination of three strains at 3.0 × 109 cfu/kg for hybrid grouper is recommended.  相似文献   

18.
Enteromyxosis caused by Enteromyxum scophthalmi is one of the parasitizations with a higher economic impact on turbot, Scophthalmus maximus (L.), aquaculture. This myxosporean produces severe catarrhal enteritis with abundant inflammatory infiltrates in the lamina propria‐submucosa (LP), epithelial detachment and leucocyte depletion of the lymphohaematopoietic organs. Some advances made on the pathogenesis pointed to a role of apoptosis in the enteromyxosis. Therefore, the main aim of this work was to employ the TUNEL assay and the anti‐(active caspase‐3) immunohistochemical assay to detect apoptotic cells in both healthy and E. scophthalmi‐infected turbot in order to establish the presence and distribution of apoptotic cells during development of the disease. More apoptotic cells located within the gastrointestinal epithelium were observed in the initial stages of the infection in E. scophthalmi‐infected turbot compared with non‐infected turbot. As the infection progressed, a higher degree of apoptosis occurred in the epithelium of folds heavily parasitized. In the severely infected turbot, apoptosis was also found among the leucocytes of the intestinal inflammatory infiltrates. Moreover, the number of active caspase‐3‐positive cells in the lymphohaematopoietic organs tended to increase with disease severity. In view of the results, increased apoptosis in the epithelium may favour the scaling that occurs during enteromyxosis and cell death of leucocytes in the intestinal LP, contributing to leucocyte depletion in severe cases.  相似文献   

19.
In response to pathogens, the higher vertebrate innate immune system activates pro‐inflammatory caspase‐1 which is responsible for the processing and secretion of several important cytokines involved in the host's defence against infection. To date, caspase‐1 has been described in few teleost fish, and its activity has been demonstrated through substrate cleavage and inhibition by pharmacological agents. In this study, the detection of the active form of caspase‐1 during the immune response in salmonid fish is described, where two antibodies were produced. These antibodies differentially recognize the structural epitopes of the inactive pro‐caspase‐1 and the processed active form of the caspase. Firstly, caspase‐1 activation was demonstrated in vitro by ELISA, Western blotting and immunocytochemistry in rainbow trout macrophages exposed to different pathogen‐associated molecular patterns plus the pathogen Aeromonas hydrophila. This activity was clearly abrogated by a caspase inhibitor and seems to be unrelated to IL‐1β secretion. Caspase‐1 activation was then validated in vivo in gill cells from fish challenged with Aeromonas salmonicida. These results represent the first demonstration of caspase‐1 activation in salmonids, and the first evidence of the putative regulatory role which this protease plays in inflammatory response in this fish group, as described for some other teleosts and mammals.  相似文献   

20.
The effects of fulvic acid (FA) on survival and immune‐related gene expression were investigated in Litopenaeus vannamei challenged with Vibrio parahaemolyticus by immersion. Shrimp were fed with different dietary FA concentrations (1, 2, 4 and 6 g/kg feed) for 20 days (first bioassay) or 8 days (second bioassay, 2 g/kg feed of FA added every 2 days) and then challenged with V. parahaemolyticus. In a third bioassay, the expression of three immune‐related genes (translationally controlled tumour protein [TCTP], superoxide dismutase [SOD] and heat‐shock protein 70 [HSP70]) in haemocytes or hepatopancreas of experimental shrimp was measured by real‐time quantitative PCR at 0, 6, 12, 24, 48, 72 and 96 hr after FA (2 g/kg feed) administration. Fulvic acid increased survival at a concentration of 2 g/kg feed supplied every two days. Interestingly, TCTP gene expression was upregulated, whereas gene expression of SOD and HSP70 was downregulated. In conclusion, dietary fulvic acid improves survival in white shrimp challenged with V. parahaemolyticus and modulates the immune response. Therefore, FA merits further evaluation as prophylactic treatment in commercial shrimp farms.  相似文献   

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