Effect of dietary supplementation of palm fruit extracts on the transcriptomes of growth,antioxidant enzyme and immune‐related genes in common carp (Cyprinus carpio) fingerlings

This study investigates the effects of date palm extracts [DPE] (Phoenix dactylifera L. Arecaceae) on growth, immune function and antioxidant system in common carp fingerlings (Cyprinus carpio). One hundred and twenty fish (4.06 ± 0.13 g) were divided into six groups fed on control diet or diets containing 200 mL kg^?1 DPE for 8 weeks. At the end of feeding trial, the expression of different genes was measured. Selected genes were grouped into three categories: growth factor genes in brain and liver [growth hormone (GH), insulin‐like growth factors I and II (IGF‐I and IGF‐II), antioxidant‐related genes in liver [glutathione S‐transferase‐alpha (GST‐α), glutathione reductase (GR) and glutathione peroxidase genes (GPX)] and immune‐related genes in head kidney [interleukin‐8 (IL‐8), interleukin‐10 (IL‐10) and transforming growth factor‐beta (TGF‐β) genes]. The relative expression of the growth‐related genes in fish fed DPE showed no significant increase compared to control group (P > 0.05). On the other hand, DPE altered the expression of genes encoding antioxidants enzymes in liver of fingerlings which was statistically significant with respect to the control samples in case GPX (P < 0.05). Also, DPE caused remarkable increases in the expression of the immune‐related genes (IL‐8, IL‐10 and TGF‐β) analysed on head kidney of common carp fingerlings compared to the control group (P < 0.05). In conclusion, it can be suggested that administration of DPE in early stages of common carp culture can promote immune efficacy and increase the antioxidant activity.     

Non‐specific immune responses and intestinal immunity of common carp (Cyprinus carpio) fed Jujube (Ziziphus jujube) fruit extract

This study investigated the effects of Jujube (Ziziphus jujube) fruit extract (JFE) as an excellent source of nutrients and phytochemicals on the innate immune responses and expression of genes involved in intestinal immunity of common carp (Cyprinus carpio) fingerlings. Three hundred healthy carps (10.78 ± 0.05 g) fingerlings were randomly allocated to 12 fibre glass tanks (300L; 15 fish per tank) and fed for 8 weeks with experimental diets which contained different levels of JFE (0%, 0.25%, 0.5%, or 1%). Thereafter, serum non‐specific immune parameters [total immunoglobulin (Ig) as well as alternative complement (ACH50) and lysozyme activity (SL)] and expression of genes involved in intestinal immunity (lyz, tnf‐alpha, il1b, il8, il10, and tgfb) were measured. The results revealed a significant elevation of Ig level in the JFE‐fed fish (p < 0.05) over the control fish. However, there was no significant difference among treated groups in case of serum total Ig. The highest levels of SL and ACH50 were observed in fish fed 1% of JFE. Nonetheless, no significant difference was noticed regarding SL and ACH50 of control and other supplemented groups (0.25% and 0.5% JFE). Also, expression of lyz, tnf‐alpha, and il1b genes increased significantly (p < 0.05) in JFE‐fed fish, in a dose‐dependent manner. On the other hand, significant (p < 0.05) down‐regulation of il110 and tgfb were noticed in treated groups. The present findings suggested that extraction of Jujube, Z. jujube fruit, possesses beneficial effects on immune responses of common carp.     

Comparative study on immunomodulatory and growth enhancing effects of three prebiotics (galactooligosaccharide,fructooligosaccharide and inulin) in common carp (Cyprinus carpio)

This study investigated the effects of different prebiotics, including galactooligosaccharide (GOS), fructooligosaccharide (FOS) and inulin (INL), on skin mucosal immune parameters, humoral immune responses as well as performance of common carp (Cyprinus carpio). Two hundred and forty specimens (13.85 ± 0.85 g) were stocked in 12 fibreglass tanks assigned into three treatments and a control group. The experimental diets were formulated to have equal level (2%) of the prebiotics. At the end of the feeding trial, the highest skin mucus lysozyme activities and total immunoglobulin (total Ig) were observed in GOS‐fed group (P < 0.05). However, skin mucus protease activity showed no significant difference among different dietary groups (P < 0.05). Blood respiratory burst activity was significantly increased in all prebiotic‐fed fish compared to the control group (P < 0.05); the highest activity was observed in GOS treatment. Furthermore, evaluation of humoral immune response revealed that feeding with GOS‐supplemented diet significantly increased lysozyme and alternative complement (ACH50) activity as well as total Ig compared to the control and other prebiotic groups. While no significant difference was observed between FOS and INL groups, common carps fed GOS‐supplemented displayed improved (P < 0.05) growth performance, including final weight, weight gain, specific growth rate (SGR) and feed conversion ratio (FCR), compared to the control treatment. These results revealed that different prebiotics modulate carp growth and immune response in different manner, and GOS seems to be the most suitable prebiotic.     

棉酚对鲤鱼急性中毒的研究

鲤鱼（体重约16克）腹腔注射乙酸棉酚0，7．3，54，100，200，400mg/kg体重，经四天（96小时）后，死亡率分别是0，0，20％，70％，90％，100％。96小时半数致死剂量是63．6mg/kg体重。注射剂量高于54mg/kg体重时，发生腹腔红肿、体壁溃烂，甚至死亡。实验结果说明虽然棉籽水平的棉酚不引起鲤鱼的任何可见的中毒症状，但是腹腔注射大剂量棉酚可引起与哺乳类相似的中毒症状。     

Effects of different dietary selenium sources (sodium selenite,selenomethionine and nanoselenium) on growth performance,muscle composition,blood enzymes and antioxidant status of common carp (Cyprinus carpio)

This experiment was conducted to compare the effects of different sources of selenium (Se) on growth, muscle Se concentration, muscle proximate composition, blood enzymes and antioxidant status of common carp, Cyprinus carpio. Organic Se (selenomethionine, SeMet), inorganic Se (sodium selenite, Na₂SeO₃), or nanoselenium were each added to the basal diet at 0.7 mg Se kg^?1 diet. Four groups of fish with an average weight of 9.69 ± 0.12 g were fed one of the experimental diets for 8 weeks. Nano‐Se diet resulted in better growth performance (P < 0.05). Fish fed with Se‐supplemented diets showed a higher (P < 0.05) Se content in the muscle and liver tissues. Fish fed nano‐Se had the highest liver glutathione peroxidase, superoxide dismutase and catalase activities (P < 0.05). Liver malondialdehyde level was significantly (P < 0.05) lower in fish fed on SeMet and nano‐Se diets as compared to control. The carp fed on nano‐Se diet had the lowest values of aspartate transaminase and alanine transaminase. Lactate dehydrogenase activity was significantly lower in fish fed on SeMet and nano‐Se diets. This study shows that nano‐Se acts more efficiently on growth performance and antioxidant defence system of common carp than organic and inorganic sources of Se.     

Glutamine precursor supplementation increases glutamine synthetase gene expression in intestine of common carp (Cyprinus carpio)

To evaluate if the addition of glutamine (Gln) precursors could enhance the utilization rate of plant protein on molecular level, the expressions of glutamine synthetase (GS) gene were analysed under supplementation of α‐ketoglutaric acid (AKG), ornithine‐α‐ketoglutaric acid (OKG), glutamic acid (Glu), and Gln. The relative quantification of GS gene expression in the plant meal (PM) group was significantly lower than the fish meal (FM) group. All the four additives increased the GS gene expression. The additive that most significantly increased the GS gene expression, Gln concentration and GS activity was glutamic acid. Supplementation of AKG in plant meal can improve the GS activity and Gln concentration. Effect of OKG on the activity of GS was not significant. The GS expression was up‐regulated by Gln, but had no significant effects on the Gln concentration and GS activity. In conclusion, substitution of plant protein for animal protein reduced the GS gene expression, and the supplementation of Gln precursors was capable of promoting the expression of GS gene in common carp.     

d‐lysine can be effectively utilized for growth by common carp (Cyprinus carpio)

An 8‐week feeding trial was conducted to compare the effects of different lysine isomers on growth, nutrient utilization and metabolic enzyme activity in common carp (Cyprinus carpio). A basic experimental diet (the control group) with 30% of dietary protein from fish meal and the remaining 70% from soybean meal was used either with or without supplementation of d‐ lysine, l‐ lysine or dl‐ lysine, respectively. The total feed intake was significantly improved by supplementation with lysine regardless of isomeric form (P < 0.05). Supplementation with d‐ lysine or l‐ lysine (but not dl‐ lysine) generally increased the weight gain, specific growth rate, feed efficiency ratio and protein efficiency ratio. Dietary lysine supplementation generally increased the apparent digestibility of dry matter, crude protein and crude lipid, but no statistically significant differences were observed between the control group and the lysine‐supplement groups (P > 0.05). The d‐ amino acid oxidase and d‐ aspartate oxidase activities were generally higher in the liver, kidney and intestine of fish fed diet containing d‐ lysine compared to fish fed diet containing l‐ lysine. The lysine, protein and lipid gains in fish were markedly increased by the supplementation with d‐ lysine or l‐ lysine, and the lysine (r = 0.618, P < 0.05) and protein gains (r = 0.671, P < 0.05) were linearly related to dietary lysine intake. Lysine retention efficiency linearly decreased with the increase of dietary lysine intake (r = ?0.579, P < 0.05). These results indicate that common carp are capable of utilizing the supplemental crystalline d‐ lysine·HCl (4 g kg^?1 dry diet) for growth when the rest of dietary amino acids are protein‐bound forms.     

Effects of antimicrobial peptides on growth,morphology of foregut villi and related genes mRNA expression in the common carp (Cyprinus carpio)

A 60‐day feeding trial was conducted to examine the effects of different levels (0, 100, 200, 400 and 600 mg/kg) of antimicrobial peptides on growth, protease activity of foregut, the morphology of foregut villi and related genes mRNA expression level in the common carp (Cyprinus carpio). The results showed that the feed of antimicrobial peptides promote common carp growth, and the optimal dosage of antimicrobial peptides is 200–333 mg/kg in the common carp feed. The protease activity of 200 and 400 mg/kg groups were significantly higher than the control and other groups (p < 0.05). The foregut villus height with 100, 200 and 400 mg/kg antimicrobial peptide groups were significantly higher than control group (p < 0.05). The crypt depth of 200 and 400 mg/kg antimicrobial peptide groups were significantly lower than control group (p < 0.05). The ratio of villus height and crypt depth of 100, 200 and 400 mg/kg antimicrobial peptide groups were significantly higher than control group (p < 0.05). The ratio with 600 mg/kg group was significantly lower than the control group (p < 0.05). The IGF‐I gene expression level of 200 mg/kg and 400 mg/kg groups were significantly higher than the control group and 600 mg/kg group (p < 0.05). The IL‐1β gene expression level of 100 mg/kg and 200 mg/kg groups were significantly higher than the control group (p < 0.05). These results indicated up‐regulation of growth and immune related genes in antimicrobial peptides fed common carp. Correlation analysis showed that IGF‐I mRNA and IL‐1β mRNA were positively correlated with SGR. IL‐1β mRNA and FCR were significantly negative correlated. It indicated that growth and immune gene common regulated the growth of the carp under antimicrobial peptides intervention. In conclusion, antimicrobial peptides can improve growth and related genes mRNA expression in the common carp. Further studies using molecular biological technique or immunologic methods are required to conclude that antimicrobial peptides are beneficial in common carp.     

Lipid metabolism responses of common carp (Cyprinus carpio L.) to mulberry leaf meal in diet

This study investigated the lipid metabolism responses of common carp (Cyprinus carpio L.) to mulberry leaf meal (MLM) replacing of some fish meal in diet. Six iso‐nitrogenous and iso‐energetic diets containing different levels of MLM (0%, 6.3%, 12.6%, 18.9%, 25.2% and 31.5%) were prepared and fed to common carps in tanks for 56 days. Analysis showed that serum total protein, albumin contents and glutamic‐pyruvic transaminase, glutamic oxalacetic transaminase activities were not significantly different among treatments, blood glucose, cholesterol, high‐density lipoprotein and low‐density lipoprotein but triglyceride concentration depicted a declining trend in MLM supplementation groups compared with control. Liver and muscle lipid content decreased with increased supplementation of MLM in the diet. Hepatic lpl showed an up‐regulated trend in the MLM groups, apo‐a1 was up‐regulated in common carp fed 31.5% MLM diet, pparα was up‐regulated in 18.9% and 25.2% MLM groups, while apo‐a4, pparβ and pparγ were down‐regulated in all the MLM‐treated groups compared with control, fabp1 was down‐regulated in fish fed high‐MLM diets (≥25.2%). The results revealed that half of fish meal in common carp diet could be replaced by MLM with no hepatotoxicity; MLM promoted the reversal of cholesterol transport thereby reducing the cholesterol in blood; MLM elevated the ability of fatty acid oxidation of the common carp, but did not activated the activity of lipoprotein lipase fully, and the suppressed transportation of fatty acid affected the degradation of triglyceride in blood together; MLM reduced liver lipid contents might through suppressing the isolation and proliferation of adipocytes.     

Effects of glutamate in low‐phosphorus diets on growth performance,antioxidant enzyme activity,immune‐related gene expression and resistance to Aeromonas hydrophila of juvenile mirror carp (Cyprinus carpio)

This study investigated the effects of glutamate (Glu) in low‐phosphorus diets on growth performance, haematological indices, antioxidant enzyme activity, immune‐related gene expression and resistance to Aeromonas hydrophila in juvenile mirror carp (Cyprinus carpio) (5.07 ± 0.02 g). Fish were fed either graded levels of Glu (0 g/kg, 5 g/kg,  10 g/kg and 20 g/kg, named G0, G0.5, G1 and G2, respectively) in a low‐phosphorus diet (15 g/kg NaH₂PO_4, 0.49), or a normal phosphorus diet ( 20 g/kg NaH₂PO_4, 0.61) without added Glu (C), for 8 weeks. At the end of the feeding trial, the fish were challenged with A. hydrophila. Compared with G0 group, 10 g/kg and 20 g/kg Glu supplementation of the low‐phosphorus diet significantly improved the final weight, WGR, SGR and PER, and decreased FCR (p < .05). Glu supplementation of the low‐phosphorus diet significantly enhanced the T‐AOC, SOD activity and GSH content in intestine (p < .05). Glu supplementation significantly reduced MDA content in foregut and midgut and increased CAT activity in midgut and hindgut (p < .05). Regarding immune‐related gene expression, Glu supplementation significantly diminished the up‐regulation of intestinal TNF‐α, IL‐1β and IL‐8 mRNA levels induced by phosphorus deficiency (p < .05). The survival rate of the G1 group was significantly higher than that of the G0 group (p < .05). In conclusion, 10 g/kg Glu supplementation in low‐phosphorus diets can improve the growth performance, enhance the activity of intestinal antioxidant enzymes and strengthen the immune function of juvenile mirror carp.     

鲤免疫应答相关基因的克隆与鉴定

为研究鲤(Cyprinus carpio L.)白细胞免疫应答相关的分子机理,以体外培养的鲤外周血白细胞为实验材料,用荧光标记的mRNA差异显示(FluoroDDRT-PCR)技术,研究丝裂原(50μg/mL LPS、50μg/mL PHA和50μg/mL ConA)在刺激白细胞4、12和24 h内诱导白细胞免疫应答相关基因的mRNA表达差异,共获得92个差异片段,其中87个片段有再扩增产物,再扩增率为94.6%;将差异片段克隆,经PCR鉴定,获得81个阳性克隆,鉴定率为93.1%;差异片段序列同源性功能分析结果表明,本研究共获得3个免疫应答相关的cDNA克隆,它们分别编码鲤的蛋白酶体激活因子PA28α亚基、翻译延伸因子(EF-1α)和基质金属蛋白酶13(Mmp13)部分序列,为进一步研究这些差异表达基因在鱼类免疫中的作用机制奠定了基础。     

Energy budget and metabolism in common carp, Cyprinus carpio L., fed on different dietary protein levels and at different ration levels

The total energy budget of 65 ± 8.0 g common carp, Cyprinus carpio L., was studied in the laboratory. The pattern of energy allocation varied with dietary protein content and ration levels. The energy lost as heat of metabolism, R, was found to increase with dietary protein level and total ration. Energy lost as faeces, F, varied from 19% to 24% of consumption, C, but did not appear to be related to either protein content or ration levels. The energy equivalent of nitrogenous excretion, U, as a proportion of C increased with an increase in dietary protein but decreased with an increase of ration level. Regression equations were developed from the data to allow prediction of respiratory energy losses, faecal losses and excretory losses. The balance of energy budgets compiled from experiments conducted over an 18-day period was between 66% and 82%. Observed growth was always less than predicted growth, so the predictive models overestimated growth. The data presented form the basis for the first reported study of total energy budgets in Cyprinus carpio.     

饲料蛋白水平对鲤幼鱼肝功能和抗氧化能力的影响

研究了不同蛋白水平饲料对鲤(Cyprinus carpio)幼鱼肝功能和抗氧化能力的影响。选用体质量为(10±1.2)g的健康鲤幼鱼,随机分为5组,每组设3个重复,每个重复35尾鱼。放养在15个规格相同的白色水箱中,分别投喂蛋白水平为30%、30.5%、31%、31.5%和32%的饲料(分别记作Diet 1、Diet 2、Diet 3、Diet 4和Diet5),饲养实验时间为8周,每隔4周对相关生理生化指标进行测定。结果表明,养殖第4和第8周时,31%蛋白水平组血清和肝胰脏的谷丙转氨酶(ALT)和谷草转氨酶(AST)活性均显著降低(P0.05);血清、肝胰脏和肾脏中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和溶菌酶(LZM)活性升高(P0.05),丙二醛(MDA)浓度显著降低(P0.05)。根据实验结果,从饲料配制的成本考虑,31%蛋白水平饲料能够达到维持鲤幼鱼机体正常的抗氧化能力以及保护肝功能的营养需求。     

The anaesthetic‐like effect of tea tree oil in common carp Cyprinus carpio L.

This study investigated the efficacy of tea tree oil (TTO) as an anaesthetic for common carp, Cyprinus carpio L., by estimation of behaviour changes and responsiveness to being taken out of the water. All applied concentrations (from 0.2 to 0.6 mL L⁻¹) resulted in sedation and immobilization. The lowest effective concentration (induction time ≤3 min, recovery time ≤10 min after 15 min of exposure) was 0.5 mL L⁻¹. Exposure in excess of 30 min at a concentration of 0.5 mL L⁻¹ caused mortality. TTO displayed distinct general anaesthetic‐like properties, fulfilling the basic requirements for a potent fish anaesthetic.     

丁香油对鲤鱼和罗非鱼的麻醉作用

本实验将丁香油按体积比加入水中制备成不同浓度梯度的麻醉剂,分别在不同水温下对两种大小规格的鲤鱼和罗非鱼进行麻醉试验.28℃水温时,随着丁香油浓度由0.05 mL·L-1到0.1mL·L-1、0.15mL·L-1增加,鲤鱼和罗非鱼麻醉时间均缩短.鲤鱼恢复时间增长,罗非鱼则缩短.在0.1mL·L-1浓度下,随着水温从21℃到24℃、26℃、28℃升高,鲤鱼和罗非鱼麻醉作用时间缩短.鲤鱼恢复时间增长而罗非鱼则缩短.28℃水温0.1mL·L-1浓度下,小鲤鱼麻醉时间比小罗非鱼短,而恢复时间比小罗非鱼长.结果显示,丁香油是一种高效、廉价的鱼类麻醉剂.     

Detoxified Jatropha curcas kernel meal as a dietary protein source: growth performance,nutrient utilization and digestive enzymes in common carp (Cyprinus carpio L.) fingerlings

Jatropha curcas kernel meal is rich in protein; however, it is toxic. Two durations of detoxification process were investigated: 30 and 60 min; designated as J_a and J_b, respectively. Common carp fingerlings (252 fish; 3.2 ± 0.07 g) were fed diets: control containing fishmeal (FM); S₅₀, J_a50 and J_b50: 50% of FM protein replaced by soybean meal (SBM), detoxified Jatropha kernel meal (DJ_aKM and DJ_bKM); S₇₅, J_a75 and J_b75: 75% of FM protein replaced by SBM, DJ_aKM and DJ_bKM. Highest body mass gain, specific growth rate, metabolic growth rate (MGR) and energy production value were observed for the J_b50 group which were statistically similar to that for control group and significantly (P < 0.05) higher than for all other groups. Lowest feed gain ratio was observed in control group, which was statistically similar to than in J_b50 group. Lowest MGR, protein efficiency ratio, protein productive value and lipid production value were observed in J_a75 group. The dry matter and lipid digestibilities were statistically (P < 0.05) highest in control group and lowest in J_a50 group. Protein and energy digestibilities were statistically similar (P > 0.05) for control and J_b50 groups, and these values were highest among the groups. Highest crude protein efficiency was observed in J_b50 group, whereas lowest in J_b75 group. Relative intestinal length and hepatosomatic index were higher in plant protein–fed groups. Intestinal amylase, protease and lipase activities for control group were statistically higher (P < 0.05) than for plant protein–fed groups. Conclusively, performance of J_b50 group was similar to control group and better than other groups and, thus, is recommended as the most optimal diet for common carp fingerlings.     

Investigation of fat content in market common carp (Cyprinus carpio) flesh during the growing season

Effects of supplemental feeding with cereals (rye, triticale, maize and the unsupplemental control group) on fat content in flesh of 3‐year‐old common carp (Cyprinus carpio) were the subject of study carried out at four ponds (Czech Republic, Central Europe) during the growing season. The main result was that supplemental feeding with cereals to the same energetic level was associated with varying growth and fat content in the flesh of common carp. At the end of the experiment, the stock of fish supplementally fed with maize was found to have the highest fat content (112.7 ± 15.6 g kg^?1), while the lowest value of fat content was found in the control group (56.8 ± 9.4 g kg^?1). The carps supplementally fed with rye were found to have a higher fat content (90.1 ± 19.0) than those supplementally fed with triticale (84.3 ± 15.7 g kg^?1). Established average fat content values (except for maize) were at the level that indicate a high sensory quality of carp flesh during the whole growing season.     

Growth performance,haematology, antioxidant status,immune response and histology of common carp (Cyprinus carpio L.) fed biofloc grown on different carbon sources

A 10 weeks trial was performed to investigate how different carbon sources (sugar beet molasses: SBM+BFT, sugar: S+BFT, corn starch: CS+BFT) along with control affect welfare status of common carp (Cyprinus carpio L.) fingerlings in biofloc‐based tanks. Three hundred healthy fingerlings (22.5 ± 0.2 g) were randomly distributed in 12 tanks (70 L) at a density of 8.02 kg/m³ (25 fish/tank). The fish in BFT treatments fed only 75% feeding rate of control. At the end of the experiment no differences were seen between the groups in case of growth performance, but the fish reared in CS+BFT had a significant lower food conversion ratio compared with the others (p < .05). Different carbon sources did not affect on haematological parameters (p > .05). Total serum protein and antibody concentration differed in treatments, and the highest values were found in S+BFT and CS+BFT treatments (p < .05). No significant differences were observed in case of lysozyme, superoxide dismutase and complement activity in treatments (p > .05), whereas the fish in BFT treatments showed a significant higher total antioxidant capacity and lower glutathione peroxidase than the control (p < .05). Different carbon sources resulted in no change in goblet and kupffer cells in intestine and liver respectively. The highest relative percentage survival was obtained in the CS+BFT and S+BFT (50%) in comparison with SBM+BFT (20%) treatment. The results obtained in this experiment, suggest that corn starch improves immune response, diseases resistance and histology of digestive and respiratory systems in carp fingerlings when used as a carbon source in zero water exchange system.