Current views on the pathogenesis of bacterial endometritis in mares

Mares with persistent and recurrent endometritis are said to be susceptible to infection; in particular they are unable to resolve the acute endometritis that always follows mating. It is thought, therefore, that these mares have a local immunological defect in the uterus that impedes the elimination of bacteria. Studies on immunoglobulins, opsonins and the functional ability of neutrophils in the uterus of susceptible mares have not confirmed the presence of an impaired immune response. It is concluded that factors involved in the production and drainage of uterine fluid may be important in the aetiology of the condition.     

Effects of protozoa on bacterial nitrogen recycling in the rumen

The effects of protozoa on ruminal NH3-N kinetics and bacterial N recycling were measured in five sheep (57.6+/-7.1 kg BW, x +/- SD) with ruminal and duodenal cannulas in naturally faunated, defaunated, and refaunated periods. The sheep were fed a diet of 239 g of alfalfa haylage and 814 g of barley concentrate per day (DM basis) divided into 12 equal portions and allocated at 2-h intervals. A pulse dose of 300 mg of 15N as [15N]NH4Cl was administered into the rumen (on d 1 and 15) and 300 mg of 15N as [15N]urea was administered intravenously to the blood (d 8). Enrichment of 15N was measured in ruminal NH3-N, bacterial N, and plasma urea N over a period of 35 h. Total collection of urine was made for 5 d and analyzed for purine derivatives to calculate the flow of microbial N. Ruminal parameters and nutrient digestibilities were also measured. Sheep were defaunated using a rumen washing procedure 50 d prior to measurements in the defaunated period. Sheep were refaunated with ruminal contents from a faunated sheep receiving the same diet. Measurements began 26 d following refaunation, at which time protozoal numbers had returned to those in the originally faunated sheep. Data reported in parentheses are for faunated, defaunated, and refaunated sheep, respectively. Total culturable and cellulolytic bacterial numbers were unaffected by defaunation, but there was an increase in flow of microbial N from the rumen (10.8, 17.3, and 11.1 g N/d; P < .05) in the defaunated period. Flux, irreversible loss, and intraruminal recycling of NH3-N and recycling of NH3-N from plasma urea N were not affected by defaunation. Defaunation had no effect on reducing the absolute amount (13.8, 10.0, and 11.3 g N/d; P > .20) of bacterial N recycling and the percentage of N flux through the bacterial N pool. Total-tract digestion was reduced in defaunated compared with faunated sheep by 8, 17, 15, and 32% for OM, N, NDF, and ADF, respectively. In conclusion, defaunation improved ruminal N metabolism through the enhancement of bacterial protein synthesis, and improvement in the flow of microbial protein to the host animal.     

早期补饲代乳料对仔猪回肠菌群及其代谢产物的影响

旨在研究早期补饲代乳料是否会对哺乳仔猪回肠菌群组成及其代谢产物造成影响。选取10窝杜×长×大仔猪,分为2组,每组5窝,分别为:母乳组(对照组)和饲喂母乳的同时添加代乳料组(试验组)。试验组仔猪吃母乳的同时从第4天开始添加代乳料,28日龄断奶后,饲喂相同日粮7 d。在仔猪28和35日龄时,每窝各选取一头仔猪进行屠宰取样。结果表明,与对照组相比,28日龄,试验组仔猪回肠食糜内丙酸、异丁酸浓度及丙酸占总短链脂肪酸的比例显著升高(P0.05),而乙酸占总短链脂肪酸的比例显著下降(P0.05);与对照组相比,35日龄试验组仔猪回肠食糜的p H值显著降低,回肠内乳酸浓度显著升高,厚壁菌门细菌的基因拷贝数显著增加(P0.05)。结果提示,早期补饲代乳料在没有影响仔猪回肠形态结构的前提下,会一定程度上改变回肠内的菌群结构及代谢产物,从而使回肠内环境维持在一个相对健康的状态。     

苜蓿细菌性病害研究进展

综述了国内外在苜蓿细菌性病害方面的研究概况。全世界现已报道9种苜蓿细菌性病害,它们是由8种细菌病原引起的,这些细菌分属于6个属。其中由革兰氏阳性细菌引起的病害1种,即苜蓿细菌性萎蔫病(Clavibacter michiganensisi subsp. insidiosus);革兰氏阴性菌引起的病害有8种,即细菌性芽萎蔫病(Erwinia persicina),细菌性芽腐烂病(Erwinia chrysanthemi),根癌土壤杆菌(Agrobacterium tumefaciens),冠腐和根腐综合病(Pseudomonas viridiflava),细菌性叶斑病和细菌性猝倒病为同一病原(Xanthomonas campestris pv. alfalfae),细菌性茎疫病(Pseudomonas syringae pv. syringae)和矮化病(Xylella fastidiosa)。我国已报道危害较轻的细菌性叶斑病(X. campestris pv. alfalfae)和细菌性茎疫病(P. syringae pv. syringae)以及2012年新报道的细菌性芽萎蔫病(E. persicina)。本文归纳了苜蓿细菌性病害的种类及其特征;列举了病害的分布及其寄主范围;详述了它们的症状识别与病原表型特征;介绍了当前常见的苜蓿细菌病原鉴定方法,即形态、生理和生化表型特征鉴定,系统发育如16S rRNA序列分析以及自动化数值分析如Biolog自动鉴定系统。     

The effect of bacterial proteases on milk proteins

The effect of proteolytic microflora on milk protein in fresh cow's milk was studied immediately after milking. The hydrolytic activity was measured by Lowry's method. When the samples were stored for 24 and 48 hours at 4 degrees C, the average value of tyrosine increased from the initial level of 0.37 mg per ml (immediately after milking) to 0.798 mg per ml (after 24 hours) and 0.811 mg per ml (after 48 hours). In milk kept at room temperature the tyrosine values were 0.865 mg per ml and 1.21 mg per ml, respectively. Higher bacterial protease activities were recorded during the first 24 hours of storage. No relationship was statistically demonstrated between tyrosine content and the number of proteolytic microorganisms in milk.     

筛选细菌毒力基因方法的研究进展

细菌的致病过程涉及多个毒力基因表达产物的相互作用。然而,随着越来越多的微生物基因组测序工作的相继或即将完成,对其毒力基因的研究却相对滞后。这不但影响了致病机理等基础研究的进展,还成为制约抗菌药物和疫苗研发的瓶颈。本文从生物信息学、筛选差异表达基因等4个方面介绍了筛选细菌毒力基因的方法及其应用,并综合了研究致病菌与宿主间相互作用关系的方法。为发现和研究致病菌新的毒力因子,理顺病原与宿主关系开拓了思路。     

氟苯尼考胁迫对土壤细菌耐药性的影响

为了了解土壤中残留氟苯尼考对土壤中细菌耐药性的影响,在土壤中添加不同浓度的氟苯尼考,于添加药物后第14天、28天、56天采集土壤样品分离细菌,采用微量肉汤二倍稀释法进行细菌对氟苯尼考的敏感性试验,并采用药敏纸片扩散法对用药前后分离的氟苯尼考敏感菌和耐药菌进行抗菌药物的敏感性试验。结果表明氟苯尼考残留的浓度越大,耐药菌的数量也就越多;在供试的18种抗菌药中,氟苯尼考敏感菌对其中的9种药物的敏感性均显著高于氟苯尼考耐药菌(P<0.01)。     

甲硝唑联合克林霉素对母牛细菌性阴道炎的疗效观察

探讨甲硝唑联合克林霉素治疗母牛细菌性阴道炎的临床效果。方法:将确诊患有细菌性阴道炎的病牛25头,分为三组。I组为观察组,患病母牛11头,用甲硝唑和克林霉素治疗;II组为对照组1,患病母牛6头,用甲硝唑治疗; III组为对照组2,患病母牛8头,用克林霉素治疗。甲硝唑注射液,5～6g/头,24 h/次,连用5d,静脉滴注;克林霉素,1.5～2g/头,24 h/次,连用5d,静脉滴注。治疗1个疗程后,对治愈母牛进行发情观察和人工授精配种。结果：①观察组临床治疗有效率为90.91％,显著高于对照组1（80.33％）和对照组2（75％）（p＜0.05）;②观察组平均治疗效果为72.25％,显著高于对照组1（64.92％）和对照组2（57.89％）（p＜0.05）③观察组、对照组1、对照组2和健康对照组牛发情率分别为81.82%、83.33%、75%和87.5%,观察组、对照组1和健康对照组显著优于对照组2,观察组、对照组1和健康对照组无显著差异;配种受胎率分别为72.72%、66.67%、62.5%和75%,观察组、健康对照组显著优于对照组1和对照组2（p＜0.05）;产活犊率分别为100%、75%、80%和100%,观察组、健康对照组显著优于对照组1和对照组2（p＜0.05）。结论：甲硝唑联合克林霉素治疗母牛细菌性阴道炎疗效显著,药物安全性高,不影响母猪的繁殖性能,具有临床推广价值;甲硝唑、克林霉素次之。