采用聚合酶链式反应-变性梯度凝胶电泳技术分析小熊猫胃肠道菌群的多样性

本试验旨在研究小熊猫胃肠道菌群多样性。采用聚合酶链式反应(PCR)-变性梯度凝胶电泳(DGGE)技术结合条带的克隆测序、聚类分析和主成分分析(PCA)检测小熊猫胃肠道菌群结构及多样性。结果表明:1)PCR-DGGE图谱显示小熊猫胃肠道中有大量菌群,且不同部位的菌群结构存在一定的差异,相邻肠段菌群结构具有一定的相似性。结肠和粪便样品的菌群多样性较高,其次为胃和直肠样品,而空肠和回肠样品菌群多样性较低。2)小熊猫胃肠道菌群PCR-DGGE图谱中测序的条带大多数归为厚壁菌门(Firmicutes)、拟杆菌门(Bacteroides)、变形菌门(Proteobacteria)和疣微菌门(Verrucomicrobia),共性条带主要是未培养拟杆菌门细菌(uncultured Bacteroidetes bacterium)、粪肠球菌(Enterococcus faecalis)、未培养梭状芽孢杆菌(uncultured Clostridium sp.)、乳酸乳球菌(Lactococcus lactis)和食窦魏斯氏菌(Weissella cibaria),其中厚壁菌门为优势菌群;特异性条带主要是丛毛单胞菌(Comamonas sp.)、梭菌属(Clostridium sp.)和Akkermansia。由此可见,小熊猫胃肠道中栖息着大量菌群,且其多样性按照胃肠道由前至后的顺序呈现高-低-高的趋势。     

带鱼酶解蛋白亚铁螯合物对泥鳅免疫特性的影响

为探究带鱼酶解蛋白亚铁螯合肽对泥鳅免疫特性的影响及其在泥鳅体内的代谢分布情况,通过在泥鳅饲料中添加不同比例带鱼酶解蛋白亚铁螯合肽,喂养40 d,检测泥鳅消化酶活性、血清和肝脏生理生化指标,运用活体成像技术检测FITC标记的带鱼酶解亚铁螯合肽在泥鳅体内的分布。结果显示,亚铁螯合肽添加量为2 g/kg时,脂肪酶活性极显著高于对照组;添加量为1 g/kg时,淀粉酶和胃蛋白酶活性显著高于正常对照组;各实验组胰蛋白酶活性相比于对照组无显著性差异。血清指标中超氧化物歧化酶和溶菌酶在添加量为2 g/kg时,活性显著高于正常对照组;相对与正常对照组,过氧化氢酶在添加量为1 g/kg表现为显著性差异,2 g/kg的添加量表现为极显著性差异;丙二醛在添加量为2 g/kg显著低于正常对照组。活体成像技术发现FITC标记的带鱼酶解蛋白亚铁螯合肽会较长时间滞留在泥鳅体内,荧光强度主要集中在泥鳅身体上部,推测带鱼酶解蛋白亚铁螯合肽被泥鳅吸收后主要分布在肝脏、胆囊等器官内。研究表明,饲料中添加1~2g/kg的带鱼酶解蛋白亚铁螯合肽能提高养殖泥鳅的消化道酶活性,增强泥鳅的非特异性免疫。     

Effect of dietary valine levels on the growth performance,feed utilization and immune function of juvenile golden pompano,Trachinotus ovatus

This experiment was designed to investigate the effects of dietary valine on the growth performance, feed utilization, digestive enzymes, serum antioxidant and immune indices of juvenile Trachinotus ovatus and determine its valine requirement. Six diets with different concentrations of L‐valine (15.0, 16.6, 18.6, 20.7, 23.5 and 25.4 g/kg dry diet, defined as diet Val‐1 to Val‐6.), were formulated to contain 430 g/kg crude protein with fish meal, soybean meal, peanut meal and precoated crystalline amino acids. Each diet was randomly assigned to triplicate treatments of 20 fish (the initial body weight was 5.34 ± 0.03 g) for 8 weeks. The results indicated that the final body weight and percent weight gain (PWG) increased with increasing valine concentration up to 18.6 g/kg (diet Val‐3), whereas the diets containing higher valine concentration reduced the growth performance significantly (p < .05). Moreover, the protein efficiency ratio, body protein deposition (BPD), muscle protein content, intestinal amylase and pepsin activities, serum T‐AOC, LZM activities, IgM, complement 3 and complement 4 concentration had a similar trend with PWG, and the trend of feed conversion ratio, serum AST, ALT activities, urea and MDA content was opposite. Meanwhile, the lipid contents of whole fish and muscle in diet Val‐6 were particularly lower than other diets (p < .05). The survival rate of diet Val‐1 was lowest in this study and was significantly lower than diet Val‐2 (p < .05). The results of polynomial regression based on PWG and BPD indicated that the optimal dietary valine requirement for Trachinotus ovatus reared in seawater‐floating net cages was 19.87–20.17 g/kg valine of dry diet, correspondingly 46.22–46.91 g/kg of dietary protein.     

Effect of the C/N ratio on inorganic nitrogen control and the growth and physiological parameters of tilapias fingerlings,Oreochromis niloticu reared in biofloc systems

The objective of this study was to document the effects of different C/N ratios on inorganic nitrogen control and the growth and health of tilapia (Oreochromis niloticus) fingerlings reared in biofloc systems. The fish (0.50 ± 0.02 g) were randomly assigned to the control group (clear water) or to one of three biofloc groups (added glucose) with a C/N ratio of 10, 15, or 20 (CN‐10, CN‐15, or CN‐20, respectively). All four groups were cultured for 120 days. The inorganic nitrogen dynamics showed that heterotrophic and autotrophic bacteria existed in the low C/N ratio group, and heterotrophic bacteria dominated the high C/N ratio group. In addition, growth was significantly better in the CN‐10 and CN‐15 groups (15.67 ± 0.78 g and 14.75 ± 0.54 g, respectively) compared to the CN‐20 (13.04 ± 0.94 g) and control (13.04 ± 0.46 g) groups (p < .05). Activities of the digestive enzymes lipase and trypsin were significantly higher in the CN‐10 and CN‐15 groups than in the control group (p < .05). In addition, activities of lysozyme, alkaline phosphatase, superoxide dismutase, glutathione and malondialdehyde were significantly higher in the CN‐10 and CN‐15 groups than in the control group (p < .05). Finally, the concentrations of glucose and cortisol in the biofloc systems were significantly lower than those in the control group (p < .05). However, the concentrations of triglyceride, aspartate transaminase and alanine aminotransferase did not differ significantly among the four groups (p > .05). At the end of the trial, an acute crowding and hypoxia stress test performed for 3 days showed that the CN‐10 and CN‐15 groups had the best survival.     

灿烂弧菌对厚壳贻贝免疫指标和消化酶活性的影响

为探究灿烂弧菌对厚壳贻贝免疫指标和消化酶活性的影响,用1×10~6、1×10~7、1×10~8个/mL 3个浓度的灿烂弧菌刺激厚壳贻贝,探讨弧菌刺激后厚壳贻贝的一氧化氮合酶(NOS)、一氧化氮(NO)、超氧化物歧化酶(SOD)、丙二醛(MAD)等免疫指标和淀粉酶、蛋白酶等消化酶的变化情况。结果显示,灿烂弧菌刺激48 h后,厚壳贻贝足、鳃、消化腺等组织中仅消化腺的NOS活性较对照组有显著升高,且酶活性随初始细菌浓度的升高而升高,故选用消化腺来测定灿烂弧菌刺激后72 h内的免疫指标和消化酶活性的变化。灿烂弧菌刺激后,48 h内NOS活性较对照组均显著升高。NO含量较对照组均显著升高,与NOS显现相同变化趋势。SOD活性在各浓度灿烂弧菌刺激下较对照组均显著升高,而MAD含量在实验组中含量显著低于对照组。淀粉酶活性在实验组中显著低于对照组,总体呈现先下降后升高的趋势。蛋白酶活性在各实验组中均呈现先升高后下降的趋势。研究表明,灿烂弧菌对厚壳贻贝免疫指标和蛋白酶活性的升高有诱导作用,但对蛋白酶的活性有抑制作用。本研究初步探明了厚壳贻贝对灿烂弧菌的免疫应答机制,为进一步研究灿烂弧菌和厚壳贻贝相互作用机制以及厚壳贻贝免疫机制奠定了基础。     

Effects of dietary carbohydrate to lipid ratio on growth,feed utilization,body composition and digestive enzyme activities of golden pompano (Trachinotus ovatus)

An 8‐week feeding trial was conducted to investigate the effects of dietary carbohydrate to lipid ratio (CHO: L) on growth, feed utilization, body composition and digestive enzyme activities of golden pompano, Trachinotus ovatus. Five iso‐nitrogenous (450 g/kg protein) and iso‐energetic (19 MJ/kg gross energy) diets with varying CHO: L ratios of 0.68, 1.02, 1.62, 2.61 and 4.35, respectively, were fed to triplicate groups of 30 fish (average 13.8 ± 0.1 g). Results showed that dietary CHO: L ratios did not show any significant influence on survival of golden pompano (p > .05) but significantly affected its growth performance and feed utilization (p < .05). Fish fed diets with CHO: L ratios at 1.62 and 2.61 exhibited the highest final body weight, weight gain ratio, specific growth rate, feed efficiency ratio and protein efficiency ratio. Fish body lipid and liver glycogen contents were also significantly influenced by CHO: L ratio (p < .05). Hepatic amylase activity increased firstly and then decreased as the dietary CHO: L ratio increased, while lipases activity decreased with increasing dietary CHO:L level. The regression model analysis showed that the most suitable dietary CHO: L ratio (protein 450 g/kg) to reach the highest weight gain ratio is 2.38.     

2～3月龄肉兔日粮消化能水平对消化代谢和产肉性能影响的研究

选用50只2月龄新西兰兔分成5组,饲喂5种消化能(DE,MJ/kg)水平的日粮(分别为9.46、10.46、11.46、12.46和13.46),测定了日粮消化能水平对2～3月龄新西兰兔生产性能、营养物质消化利用、免疫指标、小肠酶活性、盲肠内环境和肉质的影响。结果表明:日粮能量水平对日增重、料肉比影响显著(P<0.05),日增重以10.46MJ/kg组最大,为29.28g,料肉比随能量水平升高而降低;日粮能量水平对试验兔除灰分消化率外都有显著影响(P<0.05),粗蛋白(CP)消化率、氮沉积以10.46MJ/kg组最大,粗纤维(CF)和能量消化率随日粮能量水平升高而升高,脂肪和灰分消化率则随日粮能量水平升高而降低;能量水平对3月龄肉兔免疫指标影响不显著;小肠淀粉酶和脂肪酶活性随能量水平升高而增加(P<0.05);3月龄试兔盲肠内pH值、NH3-N浓度、丙酸比例和丁酸比例均随日粮能量水平升高而增加,总挥发性脂肪酸浓度(TVFA)、乙酸比例、乙丙酸比则随日粮能量水平升高而减少,其中能量水平对pH值、NH3-N含量、丁酸比例、乙酸比例的影响显著(P<0.05),而对丙酸比例、TVFA和乙、丙酸比影响极显著(P<0.01);能量水平对3月龄肉兔半净膛、全净膛屠宰率无显著影响(P>0.05),对屠体重、全净膛重、眼肌面积影响显著(P<0.05),其中屠体重以10.46MJ/kg组最高;能量水平对肉兔背最     

断奶日龄和日龄对仔猪生产性能及主要消化器官重量的影响

本试验选用12窝0～56日龄仔猪研究了断奶日龄对仔猪生产性能及主要消化器官重量的影响。试验猪在原窝不变的情况下,随机分成17、21、28、35日龄断奶4个处理组,每个处理3个重复,每个重复为1窝仔猪。试验期间,实行三阶段饲养,7日龄开始补饲,7～28日龄采食日粮I,29～42日龄采食日粮Ⅱ,43～56日龄采食日粮Ⅲ。17日龄断奶组分别于断奶后12小时、4天、4天+1周、4天+2周,21、28日龄断奶组分别于断奶后12小时、1周、2周、3周,35日龄断奶组于断奶后12小时、1周、2周剖杀,每次每个重复分别剖杀1头;同时以35日龄断奶组作为对照组,分别在17、21、28日龄断奶组剖杀时间点的相同日龄,每次每个重复也各剖杀1头,共计剖杀54头。剖杀时取胃、胰脏和肝脏称重。结果表明:断奶日龄和日龄对仔猪体重、日增重、相对生长速率和日采食量均有显著影响(P<0.05),且断奶越早,这些指标于断奶后下降的幅度越大。断奶可显著促进仔猪采食(P<0.05)。至42日龄,各处理组仔猪体重、日增重、相对生长速率及日采食量已无显著差异(P>0.05)。断奶可促进胃和胰脏的发育,但对肝脏的发育影响不大。     

玉米蛋白粉替代鱼粉对暗纹东方鲀消化酶活性的影响

研究了暗纹东方鲀肠、胃和肝胰脏等不同消化器官的消化酶活性,以及不同水平的玉米蛋白粉(0%、5%、10%、15%、20%)对暗纹东方鲀(41. 06±1. 98) g胰蛋白酶、胰凝乳蛋白酶、羧肽酶A、羧肽酶B、胃蛋白酶、氨肽酶以及脂肪酶、淀粉酶活性的影响。结果表明:(1)暗纹东方鲀肠组织中除胃蛋白酶活性显著低于胃组织,其他消化酶活性均显著高于胃和肝胰脏组织(P 0. 05);胃组织中除胃蛋白酶以外其他消化酶活性都较低。(2)玉米蛋白粉对暗纹东方鲀消化酶活性的影响因消化酶的种类各异。胰蛋白酶以10%实验组活性最大;胰凝乳蛋白酶、羧肽酶A、氨肽酶活性随玉米蛋白粉用量的增加而下降,当玉米蛋白粉用量达20%时显著低于对照组(P 0. 05)。胃蛋白酶活性10%实验组显著高于其他各组(P 0. 05);玉米蛋白粉能提高肠和肝胰脏组织脂肪酶和淀粉酶的活性,10%实验组显著高于对照组(P 0. 05)。结论:暗纹东方鲀消化酶活性以肠组织中的最高,胃组织中消化酶活性较弱;玉米蛋白粉显著影响暗纹东方鲀消化酶活性,本实验条件下,玉米蛋白粉用量为10%时暗纹东方鲀消化酶活力最高。     

代乳粉添加单宁酸对7—28日龄湖羊羔羊胃肠道发育的影响

目的 观察代乳粉中添加单宁酸对7—28日龄湖羊羔羊胃肠道生长发育的影响。方法 选择同质性好的7日龄湖羊公羔（双羔）30只,随机分为2组,每组15只,每只1个重复,分别饲喂对照代乳粉或单宁酸含量为0.2%的代乳粉,试验期21 d。羔羊28日龄时饲养试验结束,每组随机选择8只羔羊进行屠宰,分离胃室和肠段,分别称量各胃室和各肠段净质量以及含内容物质量,并量取各肠段的长度,计算各胃室和各肠段的相对质量和相对长度及内容物分布。肠道组织形态学和上皮细胞凋亡率用皱胃胃底腺区及十二指肠、空肠和回肠中段的组织样品测定。肠道屏障功能相关的闭锁蛋白（occludin）、闭锁小带1（zonula occludens-1,ZO-1）和紧密连接蛋白1（claudin 1）mRNA表达量用采集的十二指肠、空肠和回肠黏膜测定。结果 除十二指肠指数（%活体质量,P=0.012）和相对质量（%全肠质量,P=0.034;%全胃肠质量,P=0.017）、空肠和结肠相对长度（%全肠长度,P=0.030,P=0.004）及结肠内容物分布（%活体质量,P=0.039）外,单宁酸对羔羊胃肠指数（%活体质量）、胃肠相对质量（%全胃质量、%全肠质量和%全胃肠质量）、肠道相对长度（%全肠长度）、内容物相对质量（%活体质量）、胃肠内容物相对总胃/肠内容物及总胃肠内容物相对质量（%总胃内容物、总肠内容物、总胃肠内容物）以及小肠claudin 1蛋白mRNA表达量均没有产生显著影响（P＞0.05）,但显著提高羔羊十二指肠肌层厚度并降低绒毛宽度（P=0.013,P=0.001）,显著上调空肠ZO-1蛋白mRNA表达量（P=0.003）,此外,单宁酸有上调羔羊空肠occludin蛋白mRNA表达量并降低空肠绒毛宽度和隐窝深度以及空肠和回肠上皮细胞凋亡率的趋势（P=0.077,P=0.073,P=0.062,P=0.097,P=0.052）。结论 单宁酸显著降低7—28日龄湖羊羔羊十二指肠相对质量和空肠相对长度,但可通过提高十二指肠肌层厚度、上调空肠ZO-1蛋白和occludin蛋白mRNA表达量并降低空肠隐窝深度及空肠和回肠上皮细胞凋亡率来改善肠屏障功能。