Effect of dietary vitamin C on the growth performance and innate immunity of juvenile cobia (Rachycentron canadum)

This study was conducted to evaluate the effects of dietary vitamin C on growth performance, hematologic parameters and innate immune responses in juvenile cobia, Rachycentron canadum. Seven practical diets were formulated to contain 0.0 (as the basal diet), 13.6, 27.2, 54.4, 96.6, 193.4 and 386.5 mg ascorbic acid equivalent kg(-1) diet. Each diet was fed to triplicate groups of juvenile cobia with initial body weight of 5.5 g in 500-L cylindrical fiberglass tank. The results of 8 weeks feeding trial showed that typical vitamin C-deficient signs such as spinal deformation and body nigrescence were observed in the fish fed the basal diet. Fish fed the basal diet had significantly lower weight gain, specific growth rate (SGR), protein efficiency ratio (PER) and feed efficiency (FE) than those fed the diets supplemented with vitamin C, but no significant differences were observed among diets supplemented with vitamin C. However, survival rate was significantly affected by the dietary vitamin C levels, fish fed the basal diet had lower survival rate than those fed the diets supplemented with vitamin C. The ascorbic acid concentration in liver was correlated positively with the dietary vitamin C levels, however, the thiobarbituric acid reactive substances (TBARS) concentrations in liver was not significantly affected by the dietary vitamin C levels, although, fish fed the basal diet had the highest TBARS values among all treatments. The activities of serum lysozyme, superoxide dismutase (SOD), alkaline phophatase (AKP) and total immunoglobulin (Ig) were significantly influenced by the dietary vitamin C levels, fish fed the basal diet had lower lysozyme, SOD, AKP and total Ig than those fed diets supplemented with vitamin C. The serum glucose and triglyceride concentrations were significantly affected by the dietary vitamin C levels. Fish fed the basal diet had lower red blood cell and hemoglobin values than those fed the vitamin C supplemented diets. The challenge experiment with Vibrio harveyi showed that lower cumulative survival was in fish fed the unsupplemented diet, the cumulative survival were significantly increased with increase of the dietary ascorbic acid levels from 13.6 to 96.6 mg kg(-1), while the cumulative survival reached plateau when dietary ascorbic acid levels increased from 96.6 to 386.5 mg kg(-1). These results indicated that dietary vitamin C did significantly influence on growth performance and immune response of juvenile cobia.     

饲料蛋白水平对大规格草鱼生长、饲料利用和氮代谢相关酶活性的影响

为探讨饲料蛋白水平对草鱼（Ctenopharyngodon idellus）生长、饲料利用和氮代谢的影响,以鱼粉和酪蛋白为蛋白源制备蛋白水平分别为15%、20%、25%、30%和35%的5种等能（13.71 kJ/g）饲料饲养草鱼（20910） g 8周。结果表明:饲料蛋白水平对草鱼的增重率、特定生长率、饲料效率均影响显著（P0.05）,其中25%蛋白组最高。通过二次多项式的回归分析得出:当饲料蛋白水平为26.50%和27.20%的时候,特定生长率和饲料效率分别达到最高。15%蛋白组的摄食率显著高于其他蛋白组（P0.05）。蛋白质保留率和蛋白质效率随蛋白水平的升高而显著降低（P0.05）。各蛋白组的成活率、血清丙氨酸转氨酶活性和血清天冬氨酸转氨酶活性均无显著差异（P0.05）。血清总蛋白、血清尿素氮、肝脏天冬氨酸转氨酶活性、肝脏谷氨酸脱氢酶活性和肌肉腺苷酸脱氨酶活性随蛋白水平的升高显著增加（P0.05）,而肝脏丙氨酸转氨酶活性先增加后稳定,这表明高蛋白组（30%和35%蛋白组）相对于低蛋白组（15%和20%蛋白组）有较多的蛋白质用于分解代谢提供能量。       

Azadirachta indica (neem) leaf dietary effects on the immunity response and disease resistance of Asian seabass,Lates calcarifer challenged with Vibrio harveyi

The present study was aimed to address the possible evaluation of Azadirachta indica (neem) leaf-supplemented diets on innate immune response in Asian seabass, Lates calcarifer fingerlings against Vibrio harveyi infection. Fish were fed for two weeks diets containing six graded levels of neem leaf at 0 g, 1 g, 2 g, 3 g, 4 g and 5 g per kg feed. Fish fed neem leaf-supplemented diet displayed significant differences (p < 0.05) in weight gain, specific growth rate (SGR) and feed conversion ratio (FCR) compared to the control group fed without neem leaf-supplemented diet. Various innate immune parameters were examined pre-challenge and post-challenge. Fish was injected intraperitoneally with a lethal dose of V. harveyi containing 10⁸ cells mL^?1. Supplementation of neem leaf diet significantly increased phagocytic activity, superoxide anion production, serum lysozyme, serum bactericidal activity, serum anti-protease activity throughout the experimental period when compared with the control group. Dietary doses of neem leaf diet significantly influenced the immune parameters, haematological parameters and blood biochemical indices of treated fish. The results suggested that fish fed neem leaf-supplemented diet improved the immune system and increased survival rate in L. calcarifer fingerlings against V. harveyi infection.     

双低菜粕替代豆粕对青鱼幼鱼生长及生理生化指标的影响

以初始体重(5.77±0.05)g 的青鱼(Mylopharyngodon piceus)为研究对象, 以双低菜粕蛋白分别替代饲料中0 (对照)、25%、50%、75%和100%的豆粕蛋白, 配制双低菜粕含量分别为0、11%、22%、33%和44%的5 种等氮等能的实验饲料, 研究双低菜粕对青鱼生长、消化酶、消化率、体组成和部分生理生化指标的影响。实验在室内养殖系统中进行, 每水族箱(300 L)饲喂25 尾, 每处理组3 个重复, 以鱼体重3%—5%投喂量, 日投喂2 次, 试验持续8 周。实验结果表明, 当饲料中双低菜粕含量大于11%时, 其特定生长率、干物质和蛋白质表观消化率、肠道蛋白酶、淀粉酶和脂肪酶活性均显著低于对照组, 当双低菜粕含量达到44%时, 饲料系数显著高于对照组(PP<0.05)。饲料菜粕对鱼体水分和蛋白含量无显著影响, 但鱼体脂肪随菜粕含量的增加而降低、脏体比指数和灰分含量有随菜粕含量的增加而升高的趋势, 肝体比指数有随菜粕含量的增加而有先升高后降低的趋势。上述结果表明, 青鱼幼鱼饲料中双低菜粕含量以不超过11%为宜。       

Effects of dietary katuk (Sauropus androgynus L. Merr.) on growth,non-specific immune and diseases resistance against Vibrio alginolyticus infection in grouper Epinephelus coioides

This study was conducted to investigate the effect of katuk (Sauropus androgynus L. Merr) on growth, non-specific immune and diseases resistance against Vibrio alginolyticus in grouper (Epinephelus coioides). Grouper juveniles (mean weight 10.97 ± 1.99 g, and length 9.67 ± 0.33 cm) were separated into four groups and cultivated in 100-L tank. Each group was fed with diets containing 0, 1.0, 2.5 and 5.0 g/kg herbs diet twice daily. Fish were sampled for non-specific immune parameters at 0, 1, 2, 4, 7, 14 and 30 days. Results showed that fish received S. androgynus at 1.0 and 2.5 g/kg diets affected the growth and non-specific immune responses. Weight gain, specific growth rate, respiratory burst activity, phagocytosis and reactive oxygen species significantly increased in fish administered with 1.0 and 2.5 g/kg S. androgynus diets. The mortality rate after V. alginolyticus challenge decreased in fish fed with 1.0 g/kg S. androgynus extract. Thus, this study indicated that administration of grouper with S. androgynus supplemented diets can affect the growth performances, diseases resistance and enhances non-specific immune responses.     

Methionine limitation results in increased hepatic FAS activity, higher liver 18:1 to 18:0 fatty acid ratio and hepatic TAG accumulation in Atlantic salmon, Salmo salar

The current experiment aimed to study whether interactions with lipid metabolism possibly might explain the relative increased liver weight obtained in fish fed sub-optimal methionine levels. A basal diet based on a blend of plant proteins which is low in methionine (1.6 g Met/16 g N) was compared to a methionine adequate diet (2.2 g Met/16 g N) prepared by adding dl-methionine (2.4 g/kg) to the basal diet in the expense of wheat grain. Fish oil was used as the lipid source. The diets were balanced in all nutrients except methionine. The diets were fed to Atlantic salmon (500 g BW) for a period of 3 months. Feed intake did not differ, rendering the intake of all nutrients except methionine equal. Fish fed the low methionine diet had an increased liver size relative to body weight, indicating fat deposition in the liver. Fish given the sub-optimal methionine diet showed about six times higher fatty acid synthase (FAS) activity as compared to the fish fed the adequate methionine diet, indicating a higher de novo lipogenesis. A significant rise in the liver 18:1 to 18:0 fatty acid ratios also supported storage of lipids over fatty acid oxidation. Indeed, methionine limitation resulted in significantly higher TAG concentrations in the liver. Sub-optimal dietary methionine also resulted in lower hepatic taurine concentrations and the total bile acids concentrations were reduced in faeces and tended to be reduced in plasma. Taken together, our data show that salmon fed sub-optimal methionine levels had increased relative liver weight and developed signs commonly described in the early stage of non-alcoholic fatty liver disease in rodent models (increased FAS activity, changed fatty acid ratios and TAG accumulation).     

饲料中添加丝兰提取物对大菱鲆幼鱼生长和生理及水环境的影响

用丝兰提取物添加量为0.00% (D0)、0.05% (D1)、0.10% (D2)、0.20% (D3)和0.40% (D4)的实验饲料投喂大菱鲆幼鱼(42.200.06) g 60d, 研究其对大菱鲆幼鱼生长性能、体组成、血清免疫代谢指标及养殖水质指标的影响。结果显示, 在饲料中添加丝兰提取物对大菱鲆幼鱼增重率(WGR)、特定生长率(SGR)、饲料系数(FCR)、脏体比(VSI)、肝体比(HSI)、肥满度(CF)均无显著影响(P 0.05)。全鱼、肌肉及肝脏中水分、粗蛋白、粗脂肪含量变化无显著性差异(P 0.05)。D3组幼鱼血清溶菌酶显著高于其他各组(P 0.05), 而D4组各免疫指标明显低于对照组(P 0.05); D3和D4组幼鱼血清的谷丙转氨酶(ALT)、谷草转氨酶(AST)活力显著低于对照组。除A1-6h组外各实验组水体氨氮含量均显著低于对照组(P 0.05), 各实验组亚硝酸盐含量均显著高于对照组(P 0.05), 各实验组总氮、总磷、磷酸盐含量均与对照组无显著性差异(P 0.05)。研究证明, 在饲料中适量添加丝兰提取物能够显著增强大菱鲆幼鱼非特异性免疫能力, 并显著降低养殖水体氨氮含量, 对大菱鲆生长及体组成无显著影响。以非特异性免疫及水体氨氮含量为综合评定指标, 大菱鲆幼鱼饲料中丝兰提取物的适宜添加量为0.20%。       

饲料蛋白和脂肪水平对青鱼大规格鱼种生长和体组成的影响

设计5个饲料蛋白水平（30%、33%、36%、39%和42%）和2个脂肪水平（6%和9%）的52的因子试验,配制10种试验饲料,分别饲喂10组三重复平均体重为95.5 g的二龄青鱼70d,以探讨不同蛋白和脂肪水平对青鱼生长和体组成等的影响。结果表明: 鱼体增重随饲料蛋白水平从30%提高到39%不断增加（P0.05）,进一步提高饲料蛋白水平至42%时,鱼体增重则不再显著变化（P0.05）;饲料系数随饲料蛋白水平从30%提高到39%而不断降低（P0.05）,进一步提高饲料蛋白水平至42%时,也不再显著变化;蛋白质效率和蛋白保留率随饲料蛋白水平呈下降趋势;以鱼体增重为指标,经折线模型进行回归分析求得适宜的饲料蛋白水平为占干饲料的40%。饲料蛋白、脂肪水平及其交互作用对的试验鱼成活率均无显著差异（P0.05）。饲料脂肪水平、饲料蛋白与脂肪的交互作用对鱼体增重、饲料系数、摄食率和蛋白质效率也均无显著影响（P0.05）。摄食蛋白水平为30%和33%饲料的青鱼与摄食蛋白水平36%-42%饲料的青鱼相比,有较低的水分和较高全鱼脂肪（P0.05）。青鱼脏体比和肌肉粗脂肪含量均随着饲料中蛋白水平的提高呈降低的趋势。摄食脂肪水平为9%的饲料的青鱼较摄食脂肪水平为6%的饲料的青鱼,有较高脏体比、全鱼脂肪含量和肌肉粗脂肪含量（P0.05）。上述结果说明,青鱼摄食低蛋白和高脂肪的饲料造成过多的体脂积累。在试验条件下,青鱼大规格鱼种饲养阶段适宜的饲料蛋白和脂肪水平分别为占干饲料的40%和6%。       

Enhanced intestinal epithelial barrier health status on European sea bass (Dicentrarchus labrax) fed mannan oligosaccharides

The study assesses the effects of dietary mannan oligosaccharides (MOS) in European sea bass (Dicentrarchus labrax) posterior intestinal lipid class composition and its possible relation to the potential prostaglandins production and Gut Associated Lymphoid Tissue (GALT) stimulation.Fish were fed 4 g kg^?1 MOS (Bio-Mos^® Aquagrade, Alltech, Inc., USA) for eight weeks. Fish fed MOS presented higher (P ≤ 0.05) weight gain, total length, and specific and relative growth rates than fish fed the control diet. Stimulated posterior gut of fish fed MOS showed higher (P ≤ 0.05) prostaglandins production than fish fed the control diet. Lipid class analyses of posterior gut revealed a reduction (P ≤ 0.05) in the neutral lipid fraction in fish fed MOS compared to fish fed the control diet, particularly due to a reduction (P ≤ 0.05) in triacylglycerols content. The polar lipid fraction increased (P ≤ 0.05) in fish fed MOS compared to fish fed the control diet, mainly due to an increase (P ≤ 0.05) in phosphatidylethanolamine and phosphatidylcoline contents.Light microscopy of posterior gut revealed increased number or goblet cells as well as higher level of infiltrated eosinophilic granulocytes for fish fed MOS. Transmission electron microscopy qualitative observations revealed a better preserved cytoarchitecture of the intestinal epithelial barrier in the posterior gut of fish fed MOS. Posterior gut of fish fed MOS presented more densely packed non-damaged enterocytes, better preserved tight junctions structure, healthier and more organized microvilli, and a higher presence of infiltrated lymphocytes and granulocytes compared fish fed the control diet.The present study indicates that dietary MOS enhances European sea bass posterior gut epithelial defense by increasing membrane polar lipids content in relation to a stimulation of the eicosanoid cascade and GALT, promoting posterior gut health status.     

The Effect of Dietary Organic Chromium on Specific Growth Rate, Tissue Chromium Concentrations, Enzyme Activities and Histology in Common Carp, Cyprinus carpio L.

A 63-day feeding trial was carried out to investigate the effect of three levels of Cr yeast (0.5, 1.0 and 2.0?mg Cr/kg) on the utilization of diets containing 38.5?% of maize starch or dextrin in common carp, Cyprinus carpio L. (initial mean body mass 14?±?0.3?g) in an auto circulator system at 25?±?0.5?°C. A two-way analysis of variance (ANOVA) showed that the final body mass (FBM), percentage mass gain (%MG), specific growth rate (SGR) and feed conversion ratio (FCR) were significantly (P?<?0.05) affected by the two sources of variation (carbohydrate source and Cr level). In general, fish fed on a diet containing starch and fortified with 0.5?mg Cr/kg performed significantly higher FBM (47.23?g), %MG (225.11), SGR (1.91) and lower value of FCR (1.24) compared to fish fed on the other diets. Carp fed on 2.0?mg Cr/kg with maize starch and 1.0?mg Cr/kg with dextrin-based diet showed a significant reduction (P?<?0.05) in whole body lipid content as confirmed by a two-way ANOVA. Fish fed on a maize starch-based diet supplemented with 0.5 and 1.0?mg Cr/kg recorded the highest activities for hexokinase enzyme. Glucose-6-phosphate dehydrogenase activity was neither affected by Cr concentration nor by dietary carbohydrate source. Fish fed on dextrin-based diets accumulated higher Cr in the whole tissue compared to fish fed on starch-based diets. Normal histological structures in the liver and gut tissues were observed in all groups. The present data clearly showed that dietary Cr yeast was safe in the fish diet at the levels tested.     

Dietary Lipid Levels Influence Lipid Deposition in the Liver of Large Yellow Croaker (Larimichthys crocea) by Regulating Lipoprotein Receptors,Fatty Acid Uptake and Triacylglycerol Synthesis and Catabolism at the Transcriptional Level

Ectopic lipid accumulation has been observed in fish fed a high-lipid diet. However, no information is available on the mechanism by which dietary lipid levels comprehensively regulate lipid transport, uptake, synthesis and catabolism in fish. Therefore, the present study aimed to gain further insight into how dietary lipids affect lipid deposition in the liver of large yellow croaker(Larimichthys crocea). Fish (150.00±4.95 g) were fed a diet with a low (6%), moderate (12%, the control diet) or high (18%) crude lipid content for 10 weeks. Growth performance, plasma biochemical indexes, lipid contents and gene expression related to lipid deposition, including lipoprotein assembly and clearance, fatty acid uptake and triacylglycerol synthesis and catabolism, were assessed. Growth performance was not significantly affected. However, the hepato-somatic and viscera-somatic indexes as well as plasma triacylglycerol, non-esterified fatty acids and LDL-cholesterol levels were significantly increased in fish fed the high-lipid diet. In the livers of fish fed the high-lipid diet, the expression of genes related to lipoprotein clearance (LDLR) and fatty acid uptake (FABP11) was significantly up-regulated, whereas the expression of genes involved in lipoprotein assembly (apoB100), triacylglycerol synthesis and catabolism (DGAT2, CPT I) was significantly down-regulated compared with fish fed the control diet, and hepatic lipid deposition increased. In fish fed the low-lipid diet, the expression of genes associated with lipoprotein assembly and clearance (apoB100, LDLR, LRP-1), fatty acid uptake (CD36, FATP1, FABP3) and triacylglycerol synthesis (FAS) was significantly increased, whereas the expression of triacylglycerol catabolism related genes (ATGL, CPT I) was reduced compared with fish fed the control diet. However, hepatic lipid content in fish fed the low-lipid diet decreased mainly due to low dietary lipid intake. In summary, findings of this study provide molecular insight into the role of lipid deposition in the liver in response to different dietary lipid contents.     

黄连须和小檗碱对草鱼非特异性免疫系统的影响及对嗜水气单胞菌感染的抵抗作用

为了评估黄连须(FRC)和小檗碱(BBR)对草鱼(Ctenopharyngodon idella)的非特异性免疫及对抵抗嗜水气单胞菌感染的影响, 鱼喂食含1.00%、0.50%、0.25%, 0.10%, 0.00%的FRC和0.05%BBR的饲料28d。喂养28d后, 鱼注射嗜水气单胞菌, 记录感染14d后的存活率。检测NBT活性、血清溶菌酶活性、吞噬活性和补体C3水平来评价药物对草鱼的免疫反应。结果表明, 与模型组相比, 喂养饲料含有FRC和BBR的各组提高NBT活性、血清溶菌酶活性、吞噬活性和草鱼补体C3水平。喂食0.50%FRC组感染细菌后的存活率最高, 与模型组比较增加44%。FRC和BBR的体外抗菌活性采用最小抑菌浓度的方法进行了研究, 并显示出较强的抑制作用。结果表明, FRC和BBR可以用作免疫刺激剂以提高草鱼非特异性免疫和对嗜水气单胞菌引起疾病的抵抗。       

Dietary supplementation of fructooligosaccharide (FOS) improves the innate immune response, stress resistance, digestive enzyme activities and growth performance of Caspian roach (Rutilus rutilus) fry

The present study investigated the effects of prebiotic fructooligosaccharide (FOS) on the innate immune response, stress resistance, digestive enzyme activities, growth factors and survival of Caspian Roach (Rutilus rutilus) fry. After acclimation, fish (0.67 ± 0.03 g) were allocated into 12 tanks (50 fish per tank) and triplicate groups were fed a control diet or diets containing 1%, 2% or 3% FOS. At the end of the trial (7 weeks), humoral innate immune parameters (serum Ig levels, lysozyme activity and alternative complement activity (ACH50)), resistance to salinity stress (150 g L⁻¹), digestive enzyme activities (amylase, lipase and protease) and growth factors (final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR), and condition factor) were assessed. At the end of the study the innate immune responses (Ig levels, lysozyme activity and ACH50) were significantly higher in 2% and 3% FOS fed fish (P < 0.05), whereas, 1% dietary FOS only elevated serum lysozyme activity. All dietary FOS levels significantly increased resistance to a salinity stress challenge (P < 0.05) and highest survival was observed in the 3% FOS group. Similarly, digestive enzyme activities were significantly elevated with increasing levels of dietary FOS (P < 0.05). Subsequently, elevated growth performance (final weight, SGR and FCR) was observed in roach fed 2% and 3% FOS compared to the control group (P < 0.05). These results indicate that FOS can be considered as a beneficial dietary supplement for improving the immune response, stress resistance, digestive enzyme activities and growth performance of Caspian roach fry.     

Dietary methionine requirement of pre‐adult blunt snout bream, (Megalobrama amblycephala Yih, 1955)

A nine‐week feeding trial was conducted to test the hypothesis that an adequate methionine diet might improve growth, feed utilization, body composition and physiology, and biochemical parameters in pre‐adult blunt snout bream Megalobrama amblycephala, whereas a methionine deficiency might have adverse effects on these parameters. Six isonitrogenous and isoenergetics semi‐purified diets (33.0% crude protein, 7.0% crude lipid) were formulated to contain graded methionine levels (0.39–1.54% of dry weight) at 0.25% increments replaced by equal proportions of glycine. Results show that the survival rate (SR) was not significantly affected by the dietary methionine level. Final weight (FW), feed efficiency ratios (FER), weight gain (WG), and specific growth rate (SGR) increased with increasing dietary methionine levels up to 1.00% and then showed a declining trend. Using quadratic regression analysis of FER and SGR, the dietary methionine requirement was estimated to be 0.74% (2.24% of dietary protein) and 0.76% of the diet (2.30% of dietary protein), respectively. Fish fed the 0.39% methionine diet showed significantly lower whole body protein content compared to those fed with 0.85, 1.00 and 1.24% methionine diets (P < 0.05). Whole body moisture, lipid, and ash contents in pre‐adult adult blunt snout bream were not significantly affected. The urea content in fish fed the 0.85% methionine diet was significantly higher than those of fish fed a 0.39, 0.56, 1.24, 1.54% methionine diet (P < 0.05), but not significantly different in fish fed the 1.00% methionine diet (P > 0.05). No significant differences were found in other indexes such as the hepatosomatic index (HSI), viscerosomatic index (VSI), condition factor (CF), albumin (ALB), total protein (TP), alanine aminotransferase (ALT), and spartate transaminase (AST) (P > 0.05). Most important, the optimal dietary methionine level of pre‐adult blunt snout bream should be 0.74–0.76% of the diet (2.24–2.30% of dietary protein).     

Influence of dietary protein and lipid levels on growth, body composition and utilization efficiencies of Arctic charr, Salvelinus alpinus L.

Growth, body composition and feed utilization were evaluated for Arctic charr fed a control diet and nine practical diets formulated to contain three protein levels (34, 44 or 54%) at each of three lipid levels (10, 15 or 20%). Fish were raised for 24 weeks at 12° C. Increasing either dietary protein and/or lipid resulted in improved weight gain, feed efficiency and energy retained. Protein efficiency ratio and protein retained were directly related to dietary lipid and inversely related to dietary protein. A sparing effect of lipid on protein was evident where, at each protein level, Arctic charr utilized protein more efficiently with each increase in dietary lipid. Levels of 34% protein and/or 10% lipid were well below the requirements for Arctic charr (initial weight, 4.6 g). Within the range tested, the dietary combination of 54% protein with 20% lipid maximized weight gain and feed efficiency and resulted in fish with low liver and body lipid contents. However, if lowest feed cost per kg gain is an important factor, the 44% protein—20% lipid diet would be less expensive to use, although it results in a minor reduction in growth potential.     

不同脂肪源对异育银鲫的生长、体组成和肌肉脂肪酸的影响

配制了十种等氮等能的饲料饲喂3.53 g的异育银鲫幼鱼12周, 探讨异育银鲫对不同脂肪源的利用效果。十种饲料中分别添加8%的鱼油(FO)、椰子油(CNO)、玉米油(CO)、亚麻油(LO)、大豆油(SO)、菜籽油(RO)、1∶1鱼油-椰子油(FCNO)、1∶1鱼油-玉米油(FCO)、1∶1鱼油-亚麻油(FLO)和1∶1∶1∶1鱼油-椰子油-玉米油-亚麻油混合油(MIX)。每组饲料三个平行, 每个平行30尾。实验在循环水养殖系统中进行, 水温控制在(241)℃。结果表明, 在单一脂肪源中, 豆油组和椰子油组的增重率最高, 其次是菜籽油组, 鱼油、玉米油和亚麻油组的增重率最低。与相应的单一脂肪源相比, 饲料中鱼油与椰子油、玉米油或亚麻油1∶1混合后使用提高了异育银鲫的生长。摄食不同脂肪源饲料的异育银鲫血清生化指标、各组织的水分和脂肪含量差异不明显(P0.05)。肌肉脂肪酸与饲料脂肪源呈明显正相关。摄食豆油和菜籽油饲料的鱼体肌肉中20:4n-6较高, 而摄食亚麻油饲料的鱼则含有较高的20:5n-3和22:6n-3, 表明异育银鲫具有转化18:2n-6和 18:3n-3为高不饱和脂肪酸的能力。从实验可以看出, 豆油、椰子油和菜籽油是异育银鲫饲料中良好的脂肪源。       

Effects of mannan oligosaccharide dietary supplementation on performances of the tropical spiny lobsters juvenile (Panulirus ornatus,Fabricius 1798)

The effects of dietary mannan oligosaccharide (MOS) (Bio-Mos^®, Alltech, USA) on the growth, survival, physiology, bacteria and morphology of the gut and immune response to bacterial infection of tropical rock lobsters (Panulirus ornatus) juvenile were investigated. Dietary inclusion level of MOS at 0.4% was tested against the control diet (trash fish) without MOS inclusion. At the end of 56 days of rearing period, a challenged test was also conducted to evaluate the bacterial infection resistant ability of the lobsters fed the two diets. Lobster juvenile fed MOS diet attained 2.86 ± 0.07 g of total weigh and 66.67 ± 4.76% survival rate which were higher (P < 0.05) than the lobsters fed control diet (2.35 ± 0.14 g total weight and 54.76 ± 2.38% survival rate, respectively) thus providing the higher (P < 0.05) specific growth rate (SGR) and average weekly gain (AWG) of lobsters fed MOS diet. Physiological condition indicators such as wet tail muscle index (Tw/B), wet hepatosomatic index (Hiw) and dry tail muscle index (Td/B) of the lobsters fed MOS supplemented diet were higher (P < 0.05) than that of the lobsters fed the control diet. Bacteria in the gut (both total aerobic and Vibrio spp.) and gut's absorption surface indicated by the internal perimeter/external perimeter ratio were also higher (P < 0.05) when the lobsters were fed MOS diet. Lobsters fed MOS diet were in better immune condition showed by higher THC and GC, and lower bacteraemia. Survival, THC, GC were not different among the lobsters fed either MOS or control diet after 3 days of bacterial infection while bacteraemia was lower in the lobsters fed MOS diet. After 7 days of bacterial infection the lobsters fed MOS diet showed higher survival, THC, GC and lower bacteraemia than the lobsters fed the control diet. The experimental trial demonstrated the ability of MOS to improve the growth performance, survival, physiological condition, gut health and immune responses of tropical spiny lobsters juveniles.     

The influence of various feeding patterns of emodin on growth,non-specific immune responses,and disease resistance to Aeromonas hydrophila in juvenile Wuchang bream (Megalobrama amblycephala)

The present study was conducted to evaluate the effect of various feeding patterns of emodin on growth, non-specific immune response, and disease resistance to Aeromonas hydrophila in juvenile Wuchang bream. Healthy Megalobrama amblycephala (initial weight: 3.47 ± 0.032) were grown in a circulating water system for 8 weeks. Five groups were studied: one control group was fed with a basal diet for eight weeks (Pattern 1, P1), and three treatment groups were fed with a trial diet of 30 mg emodin kg⁻¹ at one-week (Pattern 2, P2), two-week (Pattern 3, P3), four-week (Pattern 4, P4) intervals. The final treatment group maintained the trial diet for the entire eight-week study duration (Pattern 5, P5). Results indicated that different feeding patterns of emodin significantly influenced the weight gain rate of Wuchang bream (P < 0.05). Fish in the P4 treatment group had significantly higher rates of weight gain (WG) than those in other treatment groups. There were no significant differences in survival rates or feed conversion ratios (FCR) between treatment groups and the control group. White blood cell count (WBC), respiratory burst activity, superoxide dismutase (SOD) activity, myeloperoxidase (MPO) activity and tumor necrosis factor-α (TNF-α) activity were shown to increase at first and then decrease from P3 condition to P5 condition. Fish under P4 treatment showed the most significant improvement of all tested parameters compared to control. Significantly higher levels (P < 0.05) of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity were observed in P2 and P4 treatment groups when compared with the control group, while no significant differences were observed in the AST and ALT activity of fish in P2, P3, P4 and P5 treatment groups. In a bacterial challenge experiment with A. hydrophila, fish under P4 and P5 treatment showed lower cumulative mortality than the control group. The results of this study suggest that an initial 4-week feeding interval is recommended for the economic and practical culture of M. amblycephala.     

Intensive culture of grass carp, Ctenopharyngodon idella, in circular tanks

Fingerling grass carp ( Ctenopharyngodon idella ) were cultured in 380 1 circular fiberglass tanks at stocking densities of 0.53, 1.06, 1.59 and 2.11 fish/1. Fish were fed duckweed ( Lemna minima ) to satiation. Fish grew from 2.7 g to a maximum mean weight of 72.7 g in 88 days. Fish stocked at 0.53 fish/1 grow more rapidly than those stocked at higher densities. Mean daily consumption rates were strongly correlated with oxygen levels and when oxygen levels dropped below 4 mg/1 consumption was reduced approximately 40%. High biomass, growth, and survival rates obtained during this study indicate grass carp are well suited for intensive tank culture.     

The influence of sulphur,molybdenum and cadmium exposure on the growth of goat,cattle and pig

A three factorial designed feeding experiment with common carp (Cyprinus carpio L.) was carried out in an intensive experimental rearing system. Fish (initial body weight 200 g) were fed on two different levels of dietary energy (16 and 18 MJ DE/kg DM), two different levels of protein (320 and 420 g CP/kg DM) and also two different feeding intensities (100% and 75% of the maximum intake). The experiment was terminated when fish reached a mean body weight of 1300 g.

Growth, feed utilization and nutrient composition of the whole body and fillet were observed. The highest growth was obtained when the fish were fed on the diet containing high dietary energy and high dietary protein with satiation feeding. High dietary energy, high dietary protein and restriction of feed intake improved feed conversion ratios. High dietary energy, low dietary protein and restrictive feeding increased energy utilization. Low dietary protein and restrictive feeding resulted in better protein utilization.

Fish fed with high dietary energy contained more fat and less protein in their carcasses. A lower fat content but higher protein and higher ash content in fish carcasses was shown when fish were fed with a diet high in protein and fed restrictively.