牦牛隐性乳房炎的调查及致病菌的分离鉴定

为调查阿坝州红原县牦牛隐性乳房炎的发病情况,无菌采取68份无临床乳房炎牦牛奶样,采用体细胞计数、细菌分离培养、革兰染色与PCR相结合的方法分离鉴定细菌种属,并统计分析体细胞数与细菌分离情况的相关性。结果显示,牦牛奶样体细胞数从4 000个/mL～240 000个/mL不等;各种细菌阳性奶样数分别为金黄色葡萄球菌1份,溶血性葡萄球菌30份,非溶血性葡萄球17份,大肠埃希菌2份,乳酸乳球菌18份和藤黄微球菌2份;未分离到无乳、停乳、乳房链球菌。结果表明,分离到溶血性葡萄球菌的牦牛奶样体细胞平均数显著高于未分离到溶血性葡萄球菌的牦牛奶样体细胞的平均数(P0.05),当牦牛奶中体细胞数大于90 000个/mL时,溶血性葡萄球菌的阳性率大于80%(10/12)。研究结果提示溶血性葡萄球菌是引起牦牛隐性乳房炎的病原菌,为牦牛隐性乳房炎的防控提供了依据。     

奶牛乳汁体细胞数的快速检测及其临床意义

本文用新型便携式体细胞计数仪C-Reader对奶牛乳汁体细胞数(SCC)进行快速、精确地检测,同时对乳样中的病原菌进行分离鉴定,旨在指导奶牛乳房炎的诊断、预防及治疗。选用北京及河北地区10个奶牛场的111头奶牛共428份奶样,进行SCC计数。SCC20万/mL的奶样占63.6%,SCC介于20万/mL～50万/mL的奶样占13.1%,SCC50万/mL占23.3%。检测的111头奶牛中,60头奶牛患有隐性乳房炎,头发病率54.1%,乳区发病率23.3%。隐性乳房炎SCC变化范围50.6万/mL～984.3万/mL。对隐性乳房炎乳样进行致病菌分离培养,其阳性率高达82.0%。共鉴定出100株致病菌,其中金黄色葡萄球菌64株,表皮葡萄球菌11株,大肠杆菌8株,链球菌10株,其他菌7株。结果表明,C-Reader计数仪能够快速准确地检测北京及河北地区的奶牛隐性乳房炎,其病原菌以金黄色葡萄球菌为主。     

奶牛场隐性乳房炎病原学研究

用加州乳房炎实验(CMT)检测烟台市某场牛群隐性乳房炎69头,137个乳区的奶样,细菌分离结果表明,头细菌检出率为75%;乳区细菌检出率为69%,从其中分离鉴定出链球菌11株,金黄色葡萄球菌5株、溶血性表皮葡萄球菌6株。另外还有大量的非溶血性表皮葡萄球菌和环境性致病菌如蜡样芽胞杆菌等,其中链球菌和葡萄球菌是引起该场隐性乳房炎的主要病原菌。     

我国规模牛场奶牛个体生鲜乳体细胞数水平及影响因素探析

本研究旨在探析我国规模奶牛场奶牛个体生鲜乳体细胞数（SCC）的水平、分布和影响因素。利用SAS9.0的GLM模型,统计分析覆盖16个省（市、区）,33个规模奶牛场,23 351头中国荷斯坦牛,从2007年至2009年连续3年的225 775条奶牛个体生鲜乳SCC检测记录。结果表明：奶牛个体生鲜乳SCC的总体均值为48×104cell/mL,标准差为117×104cell/mL,个体生鲜乳SCC波动范围较大;其中,77.9%的奶牛个体,其生鲜乳SCC小于50×104cell/mL,对群体混合样生鲜乳SCC的影响系数为0.26;11.3%的奶牛个体,其生鲜乳SCC介于50×104～100×104cell/mL之间,乳房处于隐性感染状态,对群体混合样生鲜乳SCC的影响系数为0.16;10.8%的奶牛个体,生鲜乳SCC大于100×104cell/mL,理论上乳房处于临床感染状态,对群体混合样生鲜乳SCC的影响系数为0.58。奶牛个体生鲜乳体细胞数评分（SCS）呈正态分布,与奶牛个体因素（产奶量、乳脂率、乳蛋白含量、胎次和泌乳阶段）和环境因素（泌乳月份、泌乳季节）差异极显著（P〈0.01）,与奶牛养殖区域、奶牛场差异不显著（P〉0.05）。我国规模奶牛场奶牛个体生鲜乳SCC主要在50×104cell/mL以下,依据影响参数能实现对生鲜乳SCC水平的调控。     

奶牛乳房炎无乳链球菌Fc-Sip和金黄色葡萄球菌Fc-FnBPB-ClfA亚单位疫苗的免疫试验研究

为探究由IgG FcRn介导奶牛乳房炎无乳链球菌(S. agalactiae,Sgc)和金黄色葡萄球菌(Staphylococcus aureus,Sau)保护性抗原亚单位疫苗的免疫效果,在本实验室前期研究基础上,本研究按体积11的比例将Sgc的Fc-Sip和Sau的Fc-FnBPB-ClfA两种蛋白分别与1%的盐酸左旋咪唑(1%LH)充分混合,制备两种亚单位疫苗。将即将干奶(妊娠220 d)、CMT试验为"++"以上的奶牛随机分为4组,分别将Fc-Sip+Fc-FnBPB-ClfA二联亚单位疫苗(A组)、Fc-Sip亚单位疫苗(B组)、Fc-FnBPB-ClfA亚单位疫苗(C组)通过首次肌肉免疫和二次乳头管灌注免疫方式进行免疫试验。通过免疫前后对乳样细菌分离、体细胞数测定及免疫血清抗体滴度测定,评价上述亚单位疫苗的免疫效果。结果显示,免疫前免疫组(A、B、C)奶牛的乳样细菌分离率分别为80%、90%、80%,其中Sgc检出率分别为20%、30%、10%,Sau检出率分别为30%、20%、10%;首免90 d后3个免疫组奶牛乳样细菌分离率分别降至20%、20%、40%,其中Sgc的检出率分别降至0、0、10%,Sau的检出率分别降至10%、10%、0,对照组免疫前后以上各项检测无明显变化。使用利拉伐牛奶体细胞检测仪检测免疫前后试验奶牛乳样中的体细胞数,免疫前免疫组(A、B、C)奶牛体细胞数均值分别为6.19×105个/mL、5.16×105个/mL、5.49×105个/mL,首免90 d后3个免疫组奶牛乳样中体细胞数均值分别为2.05×105个/mL、2.04×105个/mL、2. 52×105个/mL,而对照组奶牛乳样体细胞数与免疫前无明显变化。检测首免后0、7 d、14 d、28 d、60 d、90 d的血清抗体滴度,结果显示,首免后7 d,免疫组(A、B、C)80%的奶牛血清抗体滴度为11 024;第14 d后,免疫组(A、B、C)90%奶牛血清抗体滴度达到12 048;第28 d后,免疫组(A、B、C)80%奶牛血清抗体滴度在14 096～18 192,比对照组平均上升3～4个抗体滴度,对照组奶牛血清抗体滴度一直保持在1256～1512。综合分析以上试验结果显示免疫A组(Fc-Sip+Fc-FnBPB-ClfA)综合免疫效果在各免疫组中最佳。本研究结果表明Fc-Sip+Fc-FnBPB-ClfA二联亚单位疫苗对无乳链球菌和金黄色葡萄球菌性奶牛乳房炎具有较好的治疗和预防作用,为奶牛隐形乳房炎的防治提供了实验依据。     

IgG FcRn介导奶牛乳房炎无乳链球菌保护性抗原Sip亚单位疫苗的研究

为研究无乳链球菌Fc-Sip亚单位疫苗的免疫效果,并验证IgGFcRn在奶牛乳腺发生局部免疫过程中的重要作用。本研究采用大肠杆菌原核表达系统,表达了由IgGFcRn介导无乳链球菌保护性表面抗原蛋白(Sip)的融合蛋白Fc-Sip,并与佐剂混合制成Fc-Sip亚单位疫苗。选取干奶前15 d的奶牛进行加州乳房炎检测法(CMT)检测,选取120头CMT(++)以上的奶牛进行分组免疫。通过免疫前后的细菌分离试验、牛奶体细胞数测定、免疫牛血清抗体间接ELISA检测来评价该亚单位疫苗的免疫效果。结果显示,免疫前乳样细菌分菌率为86.6%,无乳链球菌检出率为46.6%;免疫后乳样分菌率降至40%,无乳链球菌检出率降至13.3%,表明Fc-Sip亚单位疫苗不但可以治疗无乳链球菌性奶牛乳房炎,还可以抑制其它奶牛乳房炎致病菌的侵入。首次免疫后60 d,免疫组80%奶牛血清抗体滴度达到1∶2 048～1∶4 096,对照组奶牛抗体滴度一直保持在1∶512。首次免疫后90 d,使用利拉伐牛奶体细胞计数仪测定实验奶牛乳样中的体细胞数,免疫组奶牛乳样体细胞数范围在0.17×10~5个/mL～3.91×10~5个/mL,对照组奶牛乳样体细胞数的范围在4.05×10~5个/mL～7.27×10~5个/mL。免疫组奶牛血清抗体滴度的升高及免疫后牛奶中体细胞数的减少,表明该亚单位疫苗促进了奶牛体液免疫反应和局部免疫反应的发生,也证明该亚单位疫苗具有降低牛奶体细胞数的作用。本研究为奶牛乳房炎无乳链球菌疫苗的研制奠定了基础。     

2018年天津市原料奶细菌总数、体细胞数及奶牛乳房炎病原菌、耐药基因调研报告

本研究旨在调查天津市原料奶细菌总数、体细胞数及乳房炎病原菌、耐药基因,了解全市原料奶的质量状况及引起奶牛乳房炎发生的主要原因。采集天津市5家乳品加工企业奶罐车的原料奶样品,用于检测体细胞数和菌落总数;采集天津市奶牛养殖场储奶罐奶样品,用于检测体细胞数;采集奶牛场临床型乳房炎发病乳区的牛奶样品,用于检测乳房炎病原菌及耐药基因。结果显示:2018年天津市乳品加工企业原料奶体细胞数平均值为44.65万/mL,标准差42.41万/mL,变异系数94.97%,最大值为225.50万/mL,最小值为1.20万/mL,SCC≤50万/mL的样品占74.37%,50万/mL200万/mL的样品占3.13%;细菌总数平均值11.54万CFU/mL,标准差26.28万CFU/mL,变异系数227.66%,最大值190.00万CFU/mL,最小值0.095万CFU/mL,细菌总数≤10万CFU/mL的样品占74.37%,10万CFU<细菌总数≤50万CFU/mL的样品占21.25%,50万CFU<细菌总数≤100万CFU/mL的样品占1.88%,100万CFU/mL<细菌总数≤200万CFU/mL的样品占2.50%。2018年天津市奶牛养殖场原料奶体细胞数平均值为38.81万/mL,标准差36.49万/mL,变异系数94.03%,最大值为210.00万/mL,最小值为0.80万/mL,SCC≤50万/mL的样品占79.17%,50万/mL200万/mL的样品占0.83%。乳房炎病原菌检测结果显示:36个样品检出病原菌,总检出率为94.74%;共检出8种病原菌,检出率最高的是乳房链球菌,检出率为73.68%,其他病原体检出率依次为:牛支原体34.21%,牛棒状杆菌13.16%,无乳链球菌10.53%,大肠杆菌5.26%,白色念球菌5.26%,停乳链球菌2.63%,铜绿假单胞菌2.63%。14个样品检出耐药基因,总检出率为36.84%;2种耐药基因的检出率分别为β-内酰胺耐药基因CTX-M934.21%,耐甲氧西林葡萄球菌耐药基因MecA 2.63%。研究表明,2018年天津市原料奶SCC及细菌总数大部分接近欧盟标准,但仍有待进一步提高;引起天津地区临床型乳房炎的3种主要致病菌为乳房链球菌、牛支原体和牛棒状杆菌。     

乳房炎对中国荷斯坦牛测定日泌乳性能及体细胞数变化的影响

旨在研究乳房炎及病原菌组成对中国荷斯坦牛测定日泌乳性能及体细胞数变化的影响.本研究于2009年9月对江苏某奶牛场140头成年中国荷斯坦泌乳牛进行乳房炎检测和DHI测定,同时对隐性乳房炎阳性乳区进行病原菌分离鉴定,并分析了不同乳房炎类型和隐性乳房炎病原菌组成对测定日泌乳性能和乳中SCC变化的影响.结果表明,该牛场临床乳房炎、隐性乳房炎和正常奶牛比例分别为10.00％、51.10％和37.90％,其中隐性乳房炎以大肠杆菌和链球菌混合感染最多(19头,占26.00％),其次为链球菌单独感染(17头,占23.30％).由1种细菌单独感染的比例为26头(占36.11％),2种或2种以上细菌混合感染为44头(占61.11％).乳房炎类型对测定日产奶量、乳糖含量、体细胞数和体细胞评分4个指标影响达到极显著水平(P＜0.01),临床乳房炎和隐性乳房炎奶牛日产奶量和乳糖含量极显著低于正常奶,同时体细胞数和体细胞评分极显著高于正常奶,而临床乳房炎奶和隐性乳房炎奶在所有检测指标上均无显著差异,但临床乳房炎奶比隐性乳房炎奶体细胞数高出约100万·mL-1.不同病原菌组成类型对乳中体细胞数和体细胞评分有极显著影响(P＜0.01),而对其它性状无显著影响(P＞0.05).混合感染奶牛测定日产奶量极显著低于单独感染奶牛(P＜0.01),同时乳中体细胞数显著高于单独感染奶牛(P＜0.01).乳房炎类型对乳中SCC的变化趋势有显著影响(P＜0.01),正常奶牛维持较低SCC的能力较强,隐性乳房炎奶牛在下一泌乳月体细胞增加的可能性较大.不同隐性乳房炎病原菌组成类型对乳中SCC的变化无显著影响.奶牛生产中隐性乳房炎发病率高,危害性也最大,不同病原菌混合感染引起的隐性乳房炎对测定日产奶量和乳中体细胞数影响最大.该结果为奶牛场采取合理措施,降低隐性乳房炎发生率提供了参考.     

不同牛奶体细胞数下牛奶体细胞分型及奶牛泌乳性能变化

本试验旨在通过研究不同牛奶体细胞数(SCC)下牛奶体细胞分型特点,进而评估奶牛泌乳性能。选择102头荷斯坦奶牛进行牛奶样品采集,检测SCC、产奶量和乳成分。根据SCC检测结果将这102份牛奶样品分为3组,低SCC组(SCC100 000个/mL)、中等SCC组(SCC为100 000~400 000个/mL)和高SCC组(SCC400 000个/mL)。通过流式细胞仪对牛奶样品中的体细胞进行分选,检测淋巴细胞、巨噬细胞和多形核嗜中性白细胞(PMN)的比例。采用标准平板计菌法对菌落总数进行计数,并通过细菌学检查对牛奶样品中的细菌进行分类鉴定。结果表明:1)在SCC100 000个/mL范围内,SCC在13 000~76 000个/mL时,淋巴细胞比例为89.43%,是健康乳腺中的主要细胞群体,当SCC增加到76 000~100 000个/mL时,PMN比例极显著增加(P0.01),达到79.68%,成为乳腺内主要细胞群体,表明早期炎症已经开始发生。SCC200 000个/mL时,PMN比例与SCC呈正相关;淋巴细胞比例与SCC呈负相关;巨噬细胞比例与SCC无明显相关性。2)鉴别出的主要病原体有金黄色葡萄球菌、凝固酶阴性葡萄球菌(CNS)、无乳链球菌等;次要病原体有绿脓杆菌、芽孢杆菌、乳酸乳球菌等。主要病原体组的牛奶样品中PMN比例(48.93%)极显著高于无病原体组(17.23%)(P0.01),显著高于次要病原体组(P0.05)。3)细菌培养阳性的牛奶样品中,感染传染型病原体的奶牛,产奶量显著下降(P0.05),酪蛋白/乳蛋白及乳糖含量显著减少(P0.05);在细菌培养阴性牛奶样品中,中等SCC(10 000~40 000个/mL)和高SCC(SCC40 000个/mL)牛奶样品中观察到酪蛋白与和乳糖含量显著降低(P0.05),高SCC牛奶样品中观察到乳蛋白含量显著降低(P0.05)。由此可见,体细胞分型可用于对奶牛乳腺健康状况做出更详细分析,特别是在低SCC的牛奶中更早地识别炎症起始发生。乳腺早期炎症反应的发生明显低于目前公认的健康乳腺牛奶SCC阈值(100 000个/mL),并且CNS可能是诱发早期乳腺炎症的潜在病原体。细菌培养阴性样品中,炎症导致高SCC牛奶中酪蛋白/乳蛋白和乳糖含量的显著降低。     

呼和浩特近郊奶牛乳样体细胞分与乳成分相关性分析

本试验旨在研究呼和浩特近郊两个奶牛场荷斯坦奶牛体细胞数(somatic cell count,SCC)变化规律及体细胞分(somatic cell score,SCS)与乳成分的相关性。试验按常规方法采集奶样,并借助Bentley FTS/FCM 400 Combi奶牛生产性能测定仪测定奶样,然后对所得数据用SPSS 17.0软件进行统计分析。结果显示,奶牛各胎次中SCC在第1胎时最低(P<0.01),在第7胎时最高(P<0.01);随着泌乳天数的增加奶样SCC亦明显增加;奶样SCC<100×10³/mL到SCC>1000×10³/mL的过度中,奶牛日产奶量和奶样乳糖含量明显降低(P<0.01),分别降低了6.07 kg(22.97%)和0.40%(8.06%),而奶样乳脂率和乳蛋白率显著升高(P<0.01),分别增加了0.32%(8.31%)和0.26%(8.05%)。秋、冬季奶样乳脂率要明显高于春、夏季奶样乳脂率(P<0.01),秋季奶样乳蛋白率最高,春季奶样乳蛋白率最低;春季奶样乳糖含量最高,秋、冬季奶样乳糖含量相对较低;冬季奶样SCC最高,而秋季奶样SCC则最低。SCS与日产奶量(-0.172)和乳糖含量(-0.283)之间存在极显著负相关(P<0.01),SCS与乳脂率(0.034)和乳蛋白率(0.111)之间存在极显著正相关(P<0.01)。因此,随着胎次增高,SCC有逐渐升高趋势;随着SCC的升高,日产奶量和乳糖含量有降低趋势,而乳脂率和乳蛋白率有升高趋势;季节对乳成分和SCC均有不同程度的影响;SCC对奶牛日产奶量、乳脂率、乳蛋白率、乳糖含量均有明显影响。     

Prevalence and herd-level risk factors for intramammary infection with coagulase-negative staphylococci in Dutch dairy herds

In this study, the prevalence of intramammary infection (IMI) with coagulase-negative staphylococci (CNS) in The Netherlands was estimated on 49 randomly selected herds with at least 40 lactating cows. In total, 4220 quarter milk samples were collected. The prevalence of CNS IMI in The Netherlands was estimated at 10.8% at quarter level and 34.4% at cow level, making it the most frequently isolated group of pathogens. Fourteen species of CNS were identified; the most frequently isolated species was Staphylococcus chromogenes (30.3%) followed by Staphylococcus epidermidis (12.9%) and Staphylococcus capitis (11.0%). Prevalence of CNS IMI was higher in heifers compared to older cows. Geometric mean quarter SCC of CNS-positive quarters was 109,000 cells/ml, which was approximately twice as high as culture-negative quarters. Quarters infected with S. chromogenes, S. capitis and Staphylococcus xylosus had a higher SCC (P<0.05) than culture-negative quarters, while quarters that were culture-positive for S. epidermidis and Staphylococcus hyicus tended to have a higher SCC than culture-negative quarters. An increased prevalence of CNS IMI was associated with the herd-level variables source of drinking water not being tap water, housing of dry cows in one group instead of multiple groups, measurement of cow SCC every month, udder health monitoring by the veterinarian, pasturing during outdoor season, percentage of stalls contaminated with milk, and BMSCC>250,000 cells/ml. Although a causal relation between these factors and prevalence of CNS is not proven and for some factors not even likely, knowledge of the associations found may be helpful when approaching CNS problems on dairy farms.     

The importance of staphylococci and threshold value of somatic cell count for diagnosis of sub-clinical mastitis in Pirlak sheep at mid-lactation

This study investigated the bacterial agents causing sub-clinical mastitis and the mean somatic cell counts (SCC) of milk in Pirlak sheep at mid-lactation. The percentage of infected udder halves was 11.4% (53/464). The most frequently isolated species were coagulase-negative staphylococci (CNS) (64.2%), followed by Staphylococcus aureus (24.5%) and Escherichia coli (11.3%). Among the CNS, the most common species was Staphylococcus epidermidis (38.2%). The other species isolated from milk samples were Staphylococcus xylosus (17.7%), Staphylococcus chromogenes (14.7%), Staphylococcus simulans (8.8%) and Staphylococcus hyicus (8.8%). The mean SCC for culture positive and negative samples was 1742×10(3) and 161×10(3) cells/ml, respectively. A significant difference (p<0.05) was determined between with and without microbial growth groups in terms of the SCC values. Threshold limit for SCC was 374×10(3) cells/ml for Pirlak sheep. In conclusion, it was considered that SCC is an important predictor of sub-clinical mastitis in Pirlak sheep. This is the first study to describe the bacterial agents causing sub-clinical mastitis and threshold limit for SCC in Pirlak sheep in Turkey.     

Prevalence and persistence of coagulase-negative Staphylococcus species in three dairy research herds

Coagulase-negative Staphylococcus species (CNS) were isolated from 11.3% (1407 of 12,412) of mammary quarter milk samples obtained from cows in three dairy research herds in 2005. Approximately 27% (383/1407) of CNS was identified to the species level. The species distribution among those CNS identified from all herds was Staphylococcus chromogenes (48%), Staphylococcus hyicus (26%), Staphylococcus epidermidis (10%), Staphylococcus simulans (7%), Staphylococcus warneri (2%), Staphylococcus hominis (2%), Staphylococcus saprophyticus (1%), Staphylococcus xylosus (1%), Staphylococcus haemolyticus (<1%), Staphylococcus sciuri (<1%), and Staphylococcus intermedius (<1%). Staphylococcuschromogenes was the predominant CNS isolated from all three herds; however, differences were seen in the prevalence of other CNS species. A total of 158 CNS (S. chromogenesn=66, S. hyicusn=38, S. epidermidisn=37, S. simulans n=10, and S. warneri n=7) were analyzed by pulsed-field gel electrophoresis (PFGE). The majority (33/41) of CNS isolated from the same mammary quarter on more than one occasion had the same PFGE pattern indicating persistence of the same infection over time. When all PFGE patterns for each CNS were analyzed, no common pulsotype was seen among the three herds indicating that CNS are quite diverse. Composite milk somatic cell count (SCC) data were obtained +/-14d of when CNS were isolated. Average milk SCC (5.32 log(10)/ml) for cows in which CNS was the only bacteria isolated was significantly higher than the average milk SCC (4.90 log(10)/ml) from cows with quarter milk samples that were bacteriologically negative.     

Evaluation of direct and indirect measures of quarter milk from crossbred buffaloes

Somatic cell count (SCC), bacteriological findings and electrical conductivity (EC) were measured in milk from 216 quarters of 54 Murrah crossbred buffaloes for characterization of buffalo milk. Mean SCC in normal, subclinical and clinical mastitic milk was 171, 799 and 6039 × 10³/mL, respectively. Coagulase negative Staphylococci (CNS) were the major organisms associated with subclinical mastitis, whereas CNS and coliforms were the predominant organisms in clinical mastitis. EC values were found to be significantly higher in buffalo milk with mammary infection. The best trade-off between sensitivity and specificity for diagnosing mastitis in buffaloes by EC score was found at the cut-off value of 3.7 mS/cm. The direct measures such as SCC, EC, bacteriological findings, and appearance of milk were found to be useful for the evaluation of udder health of buffaloes and categorization of milk.     

Correlations among the somatic cell count of individual bulk milk, result of the California Mastitis Test and bacteriological status of the udder in dairy cows

In a survey of about 3000 dairy cows producing low somatic cell count (SCC) milk and kept on a large-scale dairy farm, California Mastitis Test (CMT) positivity was found in 2714 udder quarters of 1491 cows. Pathogenic microorganisms were isolated from 57.6% of these 2714 udder quarters during bacteriological examination. The commonest pathogens were coagulase-negative staphylococci (CNS, 41%) and Staphylococcus aureus (32.5%); however, udder infections caused by environmental streptococci (12.8%) and coliform bacteria (6.8%) were also common. All pathogens resulted in a significant increase of the SCC in individual bulk milk (IBM) samples. In the case of CNS, this SCC elevation in IBM was significantly lower than in the case of infection by the other pathogens. In spite of this, because of the high number of udder infections caused by CNS, the adverse effect exerted by CNS on dairy herds is considered to be substantial. It was found that 54.6% of all CMT-positive cows produced IBM of an SCC below 400 thousand per ml. The milk produced by 41% of the 315 cows excreting S. aureus also had an SCC below 400 thousand per ml. This poses a serious risk of infection to the healthy herdmates. At the same time, 11% of the infected cows produced IBM with an SCC below 100 thousand per ml. On the basis of these findings, only the regular analysis of SCC of IBM can be a reliable indicator of chronic intramammary infection. As the SCC of milk produced by CMT-positive cows (and especially of those excreting pathogens) tended to increase with advancing lactation, the authors suggest that an efficient drying-off therapy should be used to restore udder health and, whenever justified, culling of cows cannot be avoided either.     

Prevalence of subclinical udder infections and individual somatic cell counts in three dairy goat herds during a full lactation

For dairy goats, both the determination of the somatic cell counts (SCC) and the interpretation of these values may be a problem. Several investigations have shown that SCC for goat's milk, even from not infected mammary halves, are often higher than for cows milk. In the three herds examined about 40% of mammary halves and 30% of the goats were infected. However large differences between the three herds could be observed. In most cases, infections were caused by coagulase negative staphylococci (CNS) or corynebacteria. The SCC of individual milk samples from goats without any udder infection hardly differed from those of goats with at least one udder half infected with CNS. In 20% and 30% of the cases the SCC was higher than 750'000 cells/ml, respectively. The relation between California Mastitis Test (CMT) reactions and udder infections was not very close. Over 20% of mammary halves infected with CNS showed negative CMT reactions. On the other hand, 25% of samples from mammary halves without a proven infection reacted positively. The large differences in individual cell counts on herd and animal level indicate that production and breeding systems might be important reasons for the higher SCC. As a consequence, the most common methods for or the control of udder health and udder infections (SCC, California Mastitis Test) are of limited value for goats. Since there was only a weak relation between milk quality properties and SCC, any arguments for the introduction of legal limits below 1 million cells per ml can hardly be found.     

Staphylococci isolated from healthy goats.

A study was made of the staphylococcal population on the skin and on the nasal mucosa and in the milk of 133 healthy goats. Of a total of 346 strains isolated and characterised as belonging to the genus Staphylococcus, 74 (21.4%) were coagulase-positive (68 S. aureus and 6 S. hyicus), and 272 (78.6%) coagulase-negative. The novobiocin-sensitive species S. haemolyticus (23.5%), S. warneri (16.5%), S. epidermidis (11.8%), S. chromogenes (8.5%), S. caprae (6.6%) and S. hyicus (2.6%), and the novobiocin-resistant species S. xylosus (8.5%), S. sciuri (7.4%), S. saprophyticus (4.8%), S. cohnii (2.2%), S. lentus (1.1%), S. equorum (1.1%) and S. kloosii (1.1%) were identified. Twelve (4.4%) of coagulase-negative strains remained unidentified. Strains isolated in the skin of the udder and teats of the 133 goats were mainly novobiocin-sensitive coagulase-negative staphylococci, the most prevalent species being S. haemolyticus, S. warneri and S. epidermidis. Staphylococci indicative of subclinical infection were determined in the milk of 47 (35.3%) of the 133 goats sampled.     

The role of bacterial contamination of milking utensils and disinfecting solutions as a possible cause of clinical mastitis in dairy cows

Various instruments and utensils used during milking as well as teat dip solutions were examined for contamination with coagulase-negative staphylococci (CNS). The goal of this study was to investigate the relationship between contaminated fomites and udder infection in dairy cows. A total of 344 cows from ten dairy farms with the highest rate of clinical mastitis among the farms serviced by the Ambulatory Clinic of the University of Zurich were included in the study. Each farm was visited five times. All lactating cows, with the exception of those undergoing antibiotic treatment, were examined immediately before milking using the California Mastitis Test (CMT). A milk sample was collected from positive quarters. Items used to clean the udder, which included wood wool, paper towels and disinfecting towels as well as the milker's hands and the teat dip cup were swabbed for bacteriological examination. Water samples, samples of teat dip and cleaning solutions were also collected and cultured. Our results demonstrate that cleaning and disinfecting solutions have the potential to transmit udder pathogens and cause clinical mastitis. The most common CNS isolated from quarter samples were S. saprophyticus, S. sciuri and S. chromogenes, and the most common CNS isolated from utensils, cleaning and disinfecting solutions were S. fleuretii, S. vitulus, S. equorum, S. sciuri, S. haemolyticus, S. succinus and S. saprophyticus.     

泌乳阶段与产奶季节对初产奶牛牛乳体细胞数的影响

为探究初产奶牛牛乳体细胞数在不同泌乳阶段和产奶季节的变化规律,旨在为采取合理措施降低牛乳体细胞数和改善乳品质提供理论依据,研究以2012年5月至2013年4月期间选择2126头初产奶牛13168条DHI测定记录,以泌乳阶段和产奶季节及其两者的互作作为研究因子,分析泌乳阶段和产奶季节及其互作对初产奶牛牛乳体细胞数（SCC）变化规律的影响。结果表明,泌乳阶段和产奶季节及其互作对体细胞数评分（SCS）具有极显著的影响（P〈0．0001）。初产奶牛于泌乳早期牛乳SCC较高（294．16×10^3个／mL）,随着泌乳月龄的增加,SCC逐渐降低,泌乳中期（192．71×10^3个／mL）和泌乳晚期（185．51×10^3个／mL）牛乳SCC基本保持稳定;初产奶牛泌乳早期牛乳SCS比泌乳中期和泌乳晚期极显著升高（P〈0．01）;初产奶牛牛乳SCC冬季最高（312．72×10^3个／mL）,春季次之（236．48×10^3个／mL）,秋季最低（168．59×10^3个／mL）;初产奶牛冬春季牛乳SCS比夏秋季极显著升高（P〈0．01）。奶牛乳中体细胞数受胎次、泌乳月龄、产奶季节等因素的影响。产奶季节对SCC的影响主要反映了温度和湿度因素对奶牛的影响。