益康XP替代抗生素对早期断奶藏羔羊应激和免疫的影响

选取早期断奶([55±2)日龄,体重(7.91±0.83)kg]藏羔羊42只,随机分为3组(每组14只,公母各半),饲喂基础日粮为粗蛋白和能量水平分别为18.02%和12.95 MJ/kg开口料。试验Ⅰ组为基础日粮,试验Ⅱ组为基础日粮+1%益康XP,试验Ⅲ组为基础日粮+0.03%莫能菌素。对早期断奶藏羔羊血清中反应应激的酶类指标(Cor、CK、LDH、AST、ALP)和免疫指标(IgG、IgA、IgM)进行了测定。试验结果表明:各试验组的Cor、CK、AST和LDH差异不显著(P>0.05),但Cor、CK试验Ⅱ组小于其它两组,AST试验Ⅱ组小于试验Ⅲ组、LDH试验Ⅲ组小于其它两组;ALP试验Ⅱ组明显大于试验Ⅲ组(P>0.05);试验Ⅱ组IgG、IgA、IgM高于试验Ⅰ组和试验Ⅲ组(P>0.05);试验Ⅱ组藏羔羊的日增重明显高于试验Ⅰ组和试验Ⅲ组,差异显著(P<0.01);试验Ⅱ组藏羔羊的日采食量高于试验Ⅰ组和试验Ⅲ组,试验Ⅱ组对藏羔羊的腹泻率明显低于试验Ⅰ组和试验Ⅲ组(P<0.05)。综合评价表明基础日粮中添加益康XP能减小藏羔羊的早期断奶应激,提高早期断奶藏羔羊免疫机能,是抗生素的一种优良替代品。     

Latent class analysis of the diagnostic characteristics of PCR and conventional bacteriological culture in diagnosing intramammary infections caused by Staphylococcus aureus in dairy cows at dry off

Background

Staphylococcus aureus is one of the most common causes of intramammary infections in dairy cows at dry off. Reliable identification is important for disease management on herd level and for antimicrobial treatment of infected animals. Our objective was to evaluate the test characteristics of PathoProof ™ Mastitis PCR Assay and bacteriological culture (BC) in diagnosing bovine intramammary infections caused by S. aureus at dry off at different PCR cycle threshold (Ct)-value cut-offs.

Methods

Sterile quarter samples and non-sterile composite samples from 140 animals in seven herds were collected in connection with the dairy herd improvement (DHI) milk recording. All quarter samples were analyzed using BC whereas all composite samples were analyzed with PathoProof ™ Mastitis PCR Assay. Latent class analysis was used to estimate test properties for PCR and BC in the absence of a perfect reference test. The population was divided into two geographically divided subpopulations and the Hui-Walter 2-test 2-populations model applied to estimate Se, Sp for the two tests, and prevalence for the two subpopulations.

Results

The Se for PCR increased with increasing Ct-value cut-off, accompanied by a small decrease in Sp. For BC the Se decreased and Sp increased with increasing Ct-value cut-off. Most optimal test estimates for the real-time PCR assay were at a Ct-value cut-off of 37; 0.93 [95% posterior probability interval (PPI) 0.60-0.99] for Se and 0.95 [95% PPI 0.95-0.99] for Sp. At the same Ct-value cut-off, Se and Sp for BC were 0.83 [95% PPI 0.66-0.99] and 0.97 [95% PPI 0.91-0.99] respectively. Depending on the chosen PCR Ct-value cut-off, the prevalence in the subpopulations varied; the prevalence increased with increasing PCR Ct-value cut-offs.

Conclusion

Neither BC nor real-time PCR is a perfect test in detecting IMI in dairy cows at dry off. The changes in sensitivity and prevalence at different Ct-value cut-offs for both PCR and BC may indicate a change in the underlying disease definition. At low PCR Ct-value cut-offs the underlying disease definition may be a truly/heavily infected cow, whereas at higher PCR Ct-value cut-offs the disease definition may be a S. aureus positive cow.     

两种奶牛功能性添加剂效果对比试验

选取泌乳期高产和低产奶牛各18头。高产和低产中各随机选取9头在日粮中添加纤维素复合酶,添加量为0．1kg／t精料;其余18头在日粮中添加酵母培养物,添加量为2kg／t精料。结果显示,高产组饲喂纤维素复合酶的奶牛试验期第35天时产奶量显著高于饲喂酵母培养物的奶牛（P=0．024）,低产组饲喂纤维素复合酶的奶牛试验期内产奶量呈稳步上升趋势;高产组饲喂纤维素复合酶的奶牛乳脂率在试验期28天显著高于同组中饲喂酵母培养物的奶牛（P=0．022）,乳蛋白率在试验第7天（P=0．044）和第28天（P=0．018）显著高于同组中饲喂酵母培养物的奶牛。     

松南结缕草成熟胚愈伤组织的诱导和再生

松南结缕草成熟种子经灭菌和打破休眠后,接种于含有不同浓度2,4-D的MS和N6培养基上进行愈伤组织诱导。结果表明,结缕草种子的休眠主要在于破除种壳。2,4-D浓度在2~5 mg/L对愈伤组织诱导率无明显影响。基本培养基MS和N6诱导效果相近,初生愈伤组织为白色、半透明,质地松软、水浸状。继代培养基中添加一定浓度的甘露醇、麦芽糖和ABA以及延长继代时间有助于愈伤组织的胚性化。基本培养基MS更适于结缕草初生愈伤组织致密胚性化。胚性愈伤组织在MS添加0.1 mg/L 2,4-D培养基上即可分化出大量具有根和茎叶的再生植株。     

影响紫花苜蓿花药培养因素的探讨与分析

从外植体的选取时期及处理、培养基及激素组合、培养条件等多方面分析,影响紫花苜蓿花药培养的因素,并对花粉植株倍性鉴定、驯化移栽和花粉植株的遗传稳定性进行了初步探讨。     

皇帝蕉(Musa AA)组织培养与快速繁殖技术研究

摘要：对皇帝蕉芽的消毒方法、外植体的诱导、幼芽的增殖培养、生根培养等进行了研究。结果表明：采用75%酒精60s--0.1%升汞12min（第一次8min 第二次4 min）的消毒方法,比较适宜于皇帝蕉外植体的消毒,易获得理想的无菌体系;在芽的诱导初期阶段,6-BA浓度采用5.0 mg/L,最适合皇帝蕉外植体的诱导;在幼芽的中高代增殖培养阶段,适宜采用MS 4.0mg/L6-BA 0.1mg/LNAA配方;在幼芽的高代增殖培养阶段,适宜采用MS 3.0mg/L6-BA 0.1mg/LNAA配方;在幼芽的生根阶段,适宜采用MS 2.5mg/LIBA 0.2mg/LNAA配方,幼苗生根快、根系壮实、发达,成活率高。     

苜蓿雄性不育系组织培养技术的研究

以苜蓿雄性不育系Ms-4幼嫩茎段、叶片、叶柄为外植体,诱导苜蓿雄性不育系再生植株.结果表明:叶柄是诱导愈伤组织的良好外植体,体细胞胚诱导率为90%,再生率49%.苜蓿雄性不育系插条生根的最佳处理为接种前用水进行预处理0.5h,外植体为完整插条,培养基为A1、A2,其生根率为97%,生根系数为5.3.     

培养基质,赤霉素和硼对蕨菜孢子萌发成苗影响的研究

为了提高蕨菜孢子人工培养成苗效率,对４ 种培养基质和赤霉素（ＧＡ３）、硼３ 种使用水平的孢子萌发成苗效果进行了研究。结果表明,森林土、琼脂和蛭石间原叶体数无差异,但成苗率间差异显著;森林土成苗率最高,达到４２．８６％ ;砂基上孢子虽能萌发产生片状体,但不能发育到性器官形成期;赤霉素对孢子萌发生长具有显著的促进作用,在含有０．１５×１０－ ７ ｇ／Ｌ赤霉素培养基上成苗率较高;硼可提高配子体受精成苗,并以０．０５％ 硼酸处理效果最好;赤霉素与硼有显著的互作效应,含有０．１５×１０－ ７ ｇ／Ｌ赤霉素培养基上生长的原叶体,在性器官形成期喷施０．０５％ 硼酸,成苗率高达５１．６０％ 。     

蝴蝶兰幼嫩花梗组织培养和快速繁殖

以蝴蝶兰(Phalaenopsis amabilis)幼嫩花梗获得的无菌苗的茎尖为外植体,通过在MS和1/2 MS培养基中加入不同质量浓度的6-BA、NAA、TDZ和2,4-D来筛选最佳培养基配方,从而初步建立蝴蝶兰的组织培养再生体系.结果表明,花梗用0.1%升汞消毒15 min效果最好.花梗腋芽启动培养基为1/2 M...     

仔猪胰腺细胞体外培养体系的建立

为了研究体外培养仔猪胰腺细胞的适宜条件,试验选取1日龄的仔猪胰腺组织置于冰上清洗、修剪,对消化酶、离心方式、培养皿铺被方式、培养液及添加不同促生长因子等多种因素进行筛选和优化。结果表明:0.25%胰酶消化所获得的细胞强于0.1%胶原酶消化获得的细胞,细胞清亮,易于生长;采用500 r/min离心5 min、多次离心所获得的细胞较Percoll不连续密度梯度离心和5%BSA等密度梯度离心所获得的细胞贴壁率高,生长能力强,易于培养传代;采用0.1%明胶或20μg/mL的层黏连蛋白铺被培养皿均比无铺被的培养皿获得更多的贴壁细胞;以RPMI 1640、M199、F12、L-DMEM多种培养液培养仔猪胰腺细胞,表现出多种细胞形态和生长趋势;在基础培养液中添加上皮生长因子、角质化生长因子、β-巯基乙醇和白血病细胞抑制因子、转铁蛋白与亚硒酸盐混合试剂等促干细胞增殖因子可促进不同形态细胞的增殖。说明按此方式培养可获得大量、多种细胞形态的仔猪胰腺祖/干细胞。