四种不同食性鱼类肠道微生物群落组成及多样性比较分析

本研究旨在探讨食性对鱼类肠道菌群组成和多样性的影响,并预测特定菌群对不同营养素的潜在功能。实验采用高通量16S rRNA基因测序技术,提取获得滇池高背鲫(Carassius auratus)、草鱼(Ctenopharyngodon idellus)、鳜鱼(Siniperca chuatsi)、昆明裂腹鱼(Shizothorax grahami) 4种不同食性鱼类的肠道内容物,12个样品的16S rRNA,构建文库并测序,分析这4种鱼类肠道微生物的菌落组成和多样性。结果显示,鱼类肠道菌群多样性受到食性的显著影响(P<0.05),综合表现为杂食性(滇池高倍鲫) > 草食性(草鱼) > 滤食性(昆明裂腹鱼) > 肉食性(鳜鱼)。4种鱼类具有一些相同的优势菌群：变形菌门(Proteobacteria)和厚壁菌门(Firmicutes)。然而,优势菌群在属水平上存在一定差异,如不动杆菌属(Acinetobacter)为鳜鱼的优势菌群,拟杆菌属(Bacteroides)为草鱼的优势菌群等。功能预测发现,鳜鱼肠道中以革兰氏阴性菌为主;草鱼抗病潜力略高于其他3种鱼类;约氏不动杆菌(A._ johnsonii)、鲁氏不动杆菌(A. lwoffii)和施氏假单胞菌(Pseudomonas stutzeri)可能有助于宿主对蛋白质的消化,而拟杆菌属中的某些菌群可能有助于宿主消化纤维素。综上所述,食性是影响鱼类肠道菌群组成和多样性差异化的主要因素之一,分析食性与肠道优势菌群之间的关联,探讨特异菌群的功能,可为研究鱼类营养代谢的微生物效应奠定理论基础。     

羊消化道寄生虫种类及防治措施

羊消化道的寄生虫病较多,不仅能不同程度地影响羊只的生长发育,降低生产性能,严重的还能造成羊只死亡,对养羊业危害较为严重。笔者概述了羊消化道寄生虫种类及不同地区、季节、年龄羊消化道寄生虫的感染情况,并介绍不同羊消化道寄生虫常用的驱虫药及防治策略。     

稻渔综合种养的科学范式

探讨不同养殖模式下金背鲤 (Cyprinus carpio var. Jinbei) 肠道菌群和鱼肉风味品质差异,对金背鲤的繁殖优化具有重要意义。采用高通量测序技术对稻田放养和池塘养殖模式下金背鲤的肠道微生物进行测序,利用液相色谱和顶空固相微萃取-气相色谱-离子迁移谱联用 (HS-SPME-GC-IMS) 技术测定其滋味物质、挥发性风味化合物,结合感觉阈值计算滋味活性值和相对气味活度值。结果显示：两种养殖模式的金背鲤肠道细菌群落结构差异显著,稻田放养 (FGF) 组以弧菌 (Vibrio)、拟杆菌 (Bacteroides)、交替单胞菌 (Alteromonadales)、希瓦氏菌 (Shewanella)、嗜冷假单胞菌 (Pseudomonas psychrophile) 和Brevinema属为主,池塘养殖 (FGP) 组以莫拉克斯氏菌 (Moraxella) 和克雷伯菌属 (Klebsiella) 为主;FGF组中鲜味肌苷酸含量及其滋味活性值 (1.676 g·kg⁻¹, 6.705) 远高于FGP组 (0.246 g·kg⁻¹, 0.985),FGF组鲜味氨基酸和甜味氨基酸含量 (0.143和2.052 g·kg⁻¹) 高于FGP组 (0.109和2.001 g·kg⁻¹),而其苦味氨基酸 (3.193 g·kg⁻¹) 却低于FGP组 (3.836 g·kg⁻¹);金背鲤的挥发性化合物组分复杂,其关键气味化合物 (ROAV≥1) 和对整体风味有修饰作用的化合物 (0.1≤ROAV<1) 的种类存在差异。菌属与风味物质的相关性分析显示弧菌属、拟杆菌属、克雷伯菌属和摩根菌属 (Morganella) 与风味物质呈显著相关 (0.01≤P<0.05 & 0.001≤P<0.01 & P<0.001)。研究表明,养殖模式影响了金背鲤的肠道微生物,并间接影响了其风味品质。     

Prevalence of campylobacter in pigs during fattening; an epidemiological study

Summary

Numerous epidemiological reports implicate foods of animal origin as vehicles of human campylobacteriosis. Pigs are probably an important reservoir of campylobacter and a potential source of human infection. In order to improve our knowledge of the epidemiology of campylobacter in pigs, the prevalence of campylobacter and its contamination of feed were monitored in eight pig farms. Faeces samples of pigs aged 11 and 22 weeks, and samples of rectal, ileal and gastric content at a slaughterhouse were collected for bacteriological examination. On 5 farms, subsequent groups of pigs housed in the same stalls was sampled, too. A selection of the campylobacter isolates was characterized with a genetic typing method (RFLP). More than 85% of the sampled porkers were shown to be intestinal carriers of campylobacter at all stages of fattening. Subsequent groups of pigs housed in the same stalls were all carriers, too. The level of campylobacters in the faeces tended to decrease as the pigs got older. There was no difference in the frequency and level of infection with campylobacter between porkers on different farms. The feeding system (wet feed versus dry pellets) did not seem to influence the prevalence of campylobacter although wet feed gave lower counts of Enterobacteriaceae in the faeces.

RFLP‐typing showed a high diversity of campylobacter strains at each sampling on the farm. Similarities were seen between strains isolated during two subsequent samplings of the same group of pigs, but not between strains isolated on the same farm from subsequent groups of pigs housed in the same stall. This suggests that the piglets were already infected at a young age on the breeding farm.     

饲料中添加女贞子对镜鲤生长性能、消化酶活性以及肌肉品质的影响

研究了饲料中添加女贞子Ligustrumlucidum对镜鲤Cyprinuscarpioyar．Specularis的生长性能、消化酶活性及肌肉品质的影响。试验共设5个处理组：A组为基础饲料空白对照组;B组,在基础饲料中添加200mg／kg的大蒜素（纯度为25％）;C、D、E组,在基础饲料中分别添加质量分数为0．5％、1．0％、1．5％的女贞子粉。每个处理组设置3个重复,每个重复组放10尾鱼（初始体质量为125．55g±19．14g）。试验共进行12周。结果表明：与空白组相比,添加女贞子粉试验组镜鲤的特定生长率和增重率显著降低（P〈0．05）;女贞子粉对镜鲤中肠和后肠消化酶的活性均没有显著影响（P〉0．05）;除D组外,其它试验组镜鲤前肠淀粉酶的活性显著提高（P〈0．05）;各试验组镜鲤前肠蛋白酶的活性均无显著差异（P〉0．05）;女贞子试验组镜鲤肌肉的持水能力和D组的pH1值显著降低（P〈0．05）,对肌肉营养成分无显著影响。     

长薄鳅幼鱼消化道指数和消化酶活性研究

测定了长薄鳅(Leptobotia elongate Bleeker)幼鱼(8.0～110.1 g)的消化道指数和不同体重组(10 g、30 g、50 g)幼鱼的胃、肝胰脏、前肠、中肠、后肠的淀粉酶、胃蛋白酶、胰蛋白酶及脂肪酶活性。结果:(1)长薄鳅幼鱼肝指数平均为(1.400±0.004)%,比肠长平均为(0.418±0.080),体重与体长呈幂函数相关,相关式为:W=0.019L2.818 1(R2=0.948,P<0.01,n=43);鱼体肥满度在30 g组中最高。(2)各部位消化酶活性均以蛋白酶>脂肪酶>淀粉酶;各体重组淀粉酶活性在肝胰脏中最高(P<0.05);蛋白酶活性在胃和中肠中较高;脂肪酶活性沿消化道从前至后升高;(3)各部位淀粉酶活性在各体重组间变化不大,胃蛋白酶、肠段胰蛋白酶和脂肪酶活性随体重增加而下降。本研究认为长薄鳅幼鱼为杂食、偏肉食性,其消化酶活性存在组织特异性,体重30 g左右是其营养需求转变或者生长发育的重要时期。     

克氏原螯虾幼体发育时期消化酶活力及氨基酸含量研究

采用生物化学方法对克氏原螯虾各期幼体消化酶活力与氨基酸组成进行了分析。实验结果显示,在克氏原螯虾幼体发育过程中,五种消化酶活力(胃蛋白酶、类胰蛋白酶、淀粉酶、纤维素酶和脂肪酶)表现出两种变化模式:胃蛋白酶和类胰蛋白酶在幼体发育Ⅱ龄幼体期和Ⅳ龄幼体期活力较高,其中Ⅳ龄幼体期该两种酶活力最高;淀粉酶、纤维素酶和脂肪酶活力为先增高后降低,在Ⅲ龄幼体期,三种酶的活力达到最高,但与Ⅳ龄幼体期的酶活力比较无显著差异。总氨基酸含量在幼体发育早期逐渐降低,幼体发育至Ⅲ龄幼体期,其氨基酸含量最低,Ⅳ龄幼体期又有所增加。在测定的所有氨基酸中谷氨酸含量最高,必需氨基酸中赖氨酸含量最高,单个必需氨基酸含量与必需氨基酸总量的比值(A/E)在整个胚胎发育过程中的变化趋于一致。     

粪便移植技术的应用研究

本文综述了粪便移植技术的的概念、由来、研究与进展、作用机理,展望了该技术在兽医上的应用前景,指出其在治疗动物营养代谢疾病、改善机体免疫力低下、增强屏障保护功能、调整机体能量平衡、治疗肥胖和II型糖尿病等方面的应用价值,旨在推广粪便移植疗法在兽医临床上应用。     

pH值对星突江鲽消化酶活性的影响

实验通过改变酶反应中的pH值,分析了星突江鲽蛋白酶、淀粉酶和脂肪酶的活性。结果表明,胃、肠和肝胰腺蛋白酶活性的最适pH值分别为3.8、8.2和7.8,各消化部位的最高点蛋白酶活性从高到低为:胃>肝胰腺>肠。胃、肠和肝胰腺淀粉酶活性的最适pH值分别为6.6、7.4和7.0,各消化部位的最高点淀粉酶活性从高到低为:肠>肝胰腺>胃。胃、肠和肝胰腺脂肪酶活性的最适pH值分别为7.4、7.8和7.8。各消化部位的最高点脂肪酶活性从高到低为:肝胰腺>肠>胃。     

Complex Carbohydrates Occurring in the Digestive Apparatus of Umbrina Cirrosa (L.) Fry

The glycosoaminoglycans in the digestive apparatus of immature fish have important biological functions and are involved in morphofunctional differentiation. The aim of this study was to investigate the glycoconjugate histochemistry in the different parts of the digestive apparatus (oesophagus, stomach, intestine) of Umbrina cirrosa (L.) fry using classical histochemical reactions (periodic acid-Schiff, Alcian blue pH 2.5, Alcian blue/periodic acid-Schiff, high iron diamine, low iron diamine) in conjunction with glycolytic digestions that degrade different classes of glycosoaminoglycans. No differences were observed in the reactivity to conventional histochemical staining of the oesophagus, stomach or intestine among 27-, 34- or 44-day-old fry. In the oesophagus, the mucopolysaccharides contained chondroitin sulphates B and A and/or C, heparan sulphate and chondroitin. In the stomach, only neutral glycoconjugates were revealed, whereas in the intestine there were only chondroitin sulphates. Some differences in the type and content of glycoconjugates were found in Umbrina cirrosa (L.) fry compared to those of adult subjects, probably related to different dietary habits and to changes in the environmental conditions.