Evaluation of the California Mastitis Test as a precalving treatment selection tool for Holstein heifers

The objective of this study was to evaluate the California Mastitis Test (CMT) and a portable electrical conductivity meter for diagnosing precalving intramammary infection (IMI) in Holstein heifers. A total of 428 dairy heifers from 23 dairy herds were enrolled between 6 and 12 days before the expected calving date from June 2002 to June 2003. Mammary secretions were tested by both diagnostic methods and by bacterial culture for evidence of IMI. California Mastitis Test was considered negative if the score was negative, trace or 1 and was considered positive otherwise. Two cut-off points were evaluated for milk electrical conductivity (>5 and >6.5 mS/cm). From this study, an overall proportion of 69% of heifers had precalving IMI and the overall heifer prevalence of major pathogen IMI was 16.8%. At the quarter level, sensitivity and specificity of CMT (68.9% and 68.4%, respectively) and milk conductivity >5 mS/cm (41.0% and 65.2%, respectively) or >6.5 mS/cm (25.2% and 83.3%, respectively) to identify all IMI were low. However, the heifer level sensitivity and specificity of CMT for major pathogens were 91.0% (81.5-96.6) and 27.5% (22.8-32.6), respectively. Using a cut-off point of 5 mS/cm, the heifer level sensitivity and specificity for major pathogens was 68.7% (56.2-79.4) and 44.1% (38.7-49.6), respectively. A conductivity cut-off value of 6.5 mS/cm decreased the sensitivity and increased the specificity to 53.7% (41.1-66.0) and 59.5% (54.0-64.8), respectively. California Mastitis Test and milk electrical conductivity are not good predictors of major pathogen IMI in heifers during the last 2 weeks before calving. However, the negative predictive values at quarter or heifer level were high and the heifer false negative rate was 6-14% using CMT or conductivity, respectively. Therefore, these measures could be useful for screening out heifers or quarters that are unlikely to have a major pathogen IMI.     

Relationship between California Mastitis Test score and ultrasonographic teat measurements in dairy cows

Objective The majority of published studies about mastitis are related to the control and prevention of mastitis, with particular emphasis on eliminating predisposition factors. The objective of the current study was to determine the role of teat morphology as an important factor in the aetiology of mastitis. Design Ultrasonographic measurements were taken from 190 teats from 100 dairy cows of different breeds. Procedure Mastitis in cows was diagnosed by the California Mastitis Test (CMT) and microbiological tests. The data were evaluated in the light of the clinical history of the animals. Results Main effects of breed on teat diameter at the position of the Furstenberg rosette (FTD) and teat cistern diameter (CD), that of age on FTD and overall teat diameter (OTD), and that of CMT score on CD and OTD were significant (P < 0.05, P < 0.01). Number of lactations, pregnancy, the lactation period and the udder lobe (rear, front) were not found to have a significant effect on any of the measurements. Results showed that CD was significantly smaller (1.44 ± 0.04 cm) (P < 0.01) in CMT‐positive udder lobes than that in CMT‐negative lobes. No difference was detected in canal length, CD, teat wall thickness, OTD or FTD between the CMT‐positive and ‐negative lobes. Conclusion The occurrence of mastitis could be related to specific ultrasonographic teat measurements (e.g. CD, OTD and FTD) and these may be important in the breeding of cows with a predisposition to mastitis, as well in the evaluation of in‐herd cows in terms of udder/teat deformities.     

奶牛乳腺炎病原菌的分离及其药敏试验

在临床调查的基础上,采用普通琼脂培养分离临床型乳腺炎奶牛的病原菌,并用平板纸片法进行药物敏感试验,以确定农场奶牛临床型乳腺炎的致病菌种类及致病菌对不同抗生素的敏感性.结果发现,患临床型乳腺炎奶牛的主要致病菌是葡萄球菌和链球菌,有部分大肠杆菌;泰诺、氨苄青霉素钠、先锋9号和盐酸环丙沙星的抑菌效果较好.结合临床治疗效果观察发现,盐酸环丙沙星对乳腺炎的治疗效果最佳.     

奶牛乳房炎病原菌分离鉴定及药敏试验

通过对锡林浩特市周边奶牛养殖户奶牛的62份临床型乳房炎奶样的细菌分离培养,共分离出5类36株细菌,细菌检出率为58.06%,其主要致病菌为葡萄球菌、链球菌、大肠杆菌、巴氏杆菌。并依据乳房炎发病机理,选择具有抑菌、活血化瘀、控制炎症反应、改善局部微循环作用的中药针剂进行药敏试验。市售以复方蒲公英野菊花注射液、复方地丁注射液、复方野菊花夏枯草注射液具有良好的抑菌清热、活血化瘀、止血、止痛等功效,可作为治疗临床型乳房炎的首选药物,降低抗生素奶源和弃奶损失,保证消费者健康。     

Association of California Mastitis Test Scores with Intramammary Infection Status in Lactating Dairy Cows Admitted to a Veterinary Teaching Hospital

Background

Subclinical mastitis is of concern in veterinary hospitals because contagious mastitis pathogens might be unknowingly transmitted to susceptible cows and then back to their farm of origin.

Objectives

To evaluate the California mastitis test (CMT) as an indicator of intramammary infection (IMI) in lactating dairy cows admitted to a veterinary hospital.

Animals

A total of 139 admissions of 128 lactating dairy cows admitted to the University of Illinois Veterinary Teaching Hospital over a 2‐year period.

Methods

A retrospective study with a convenience sample was conducted. Medical records of cows with CMT results and milk culture results for the day of admission were reviewed. Breed, age, season, maximum CMT score for the 4 quarters, maximum CMT score difference, and clinical diagnosis were evaluated as predictors of IMI by the chi‐square test and stepwise logistic regression.

Results

An IMI was identified in 51% of quarters. For cows admitted without evidence of clinical mastitis, the sensitivity of a CMT score ≥trace in predicting an IMI on a quarter or cow basis was 0.45 and 0.68, respectively. The distributions of maximal quarter CMT score and the maximum difference in quarter CMT score for cows without evidence of clinical mastitis did not differ (P = 0.28, P = 0.84, respectively) for cows with and without IMI. Stepwise logistic regression did not identify significant predictors of IMI in cows without clinical mastitis.

Conclusions

Lactating dairy cattle admitted to a veterinary hospital should be managed as if they have an IMI, even in the absence of clinical mastitis.     

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.     

奶牛临床型乳腺炎病原菌分离试验

通过对３４份患临床型乳腺炎的乳样进行细菌分离培养及初步生化反应鉴定,检出肠科细菌１２株,检出率为３５．３％;球菌２６株,检出率为７６．５％;酵母菌９株,检出率为２６．５％;另有７份乳样在整个分离培养过程中未见有细菌生长,占总检样的２０．６％。     

奶牛乳房炎金黄色葡萄球菌的分离鉴定及药敏试验

[目的] 了解泰州市某奶牛场乳房炎中金黄色葡萄球菌（Staphylococcus aureus）感染情况及其对常用药物的敏感性。[方法] 试验选用Baird-Parker培养基分离、生化鉴定、PCR检测等方法,对采集的9份奶牛乳房炎奶样进行分离鉴定和药敏试验。[结果] 共分离到6株葡萄球菌,进一步通过凝固酶试验和16S rDNA测序等方法鉴定其中3株为金黄色葡萄球菌。药敏试验结果显示,3株金黄色葡萄球菌对青霉素G均耐药,2株对四环素耐药,2株对红霉素和苯唑西林表现为中介。[结论] 该次分离的金黄色葡萄球菌主要对青霉素G和四环素耐药,对其他常用抗生素表现为敏感。     

奶牛乳房炎MTT检测方法的药敏试验研究

用MTT法对奶样中细菌进行药敏试验（氨苄青霉素、复方新诺明、头孢噻肟、头孢唑林钠、链霉素、红霉素、庆大霉素、阿米卡星和氟哌酸9种抗菌药）,并与传统的纸片琼脂扩散法进行比较研究。结果表明,除了氟哌酸抑菌结果有差异,奶样中的细菌对链霉素、红霉素和复方新诺明耐药,对庆大霉素和阿米卡星中度敏感,对氨苄青霉素、头孢唑林钠、头孢噻肟敏感,两种试验方法的结果基本一致。说明MTT法可作为药敏试验的一种方法,直接用于检测乳房炎奶牛的细菌药敏试验。     

用溴麝香草酚蓝试验测定奶牛乳房炎的报告

应用溴麝香草酚蓝试验测定牛乳pH值的方法,对来自青海省门源县大滩地区农牧户户饲养的500头奶牛进行了奶牛乳房炎的测定;结果检出：奶牛阳性乳汁52份,乳房炎阳性率为10.4％.这说明在该地区的牛群中存在着奶牛乳房炎的感染.     

Bacterial cure and somatic cell count response of dairy cows with a positive California Mastitis Test at calving to therapy with cephapirin sodium

Cows without signs of clinical mastitis were evaluated by the California Mastitis Test at calving (Day 0). Milk samples from 117 of 184 quarters (64 cows) were positive by this test for mastitis and were submitted for bacterial culture and determination of somatic cell counts. Cows with infected quarters were randomly allocated to treatment with cephapirin sodium by intramammary infusion or to be untreated as controls. Two and 4 weeks following calving, milk was again sampled from the infected quarters and tested. By the 4-week evaluation, the quarters treated with cephapirin sodium had significantly (P < or = .05) fewer positive bacterial cultures and somatic cell counts were significantly (P < or =.05) reduced compared with untreated control quarters.     

山羊临床型乳房炎主要病原菌分离鉴定及药敏试验

为调查四川省资阳市某规模化羊场暴发乳房炎的主要病原菌,无菌采集患病羊乳样45份,然后进行细菌分离、纯化及PCR鉴定,同时对分离菌株进行耐药性试验。共分离、鉴定出5株大肠埃希菌、30株金黄色葡萄球菌和25株链球菌。药敏试验结果显示,分离菌株对青霉素、氨苄西林、庆大霉素、红霉素及四环素类等多种药物有耐药性。本研究为该场山羊乳房炎的防控提供了依据。     

荷斯坦牛隐性乳房炎主要病原菌的耐药性试验

对新疆石河子市某奶牛场进口的澳大利亚荷斯坦牛隐性乳房炎的发病情况进行调查，同时采集部分乳样进行细菌的分离鉴定，结果发现其中主要致病菌为链球菌、金黄色葡萄球菌、大肠杆菌等，并分别选取了15种常用抗生素进行了药物敏感试验。结果表明：致病菌对临床上常用的青、链霉素及磺胺类等药物均已产生不同程度的耐药性,而喹诺酮类药物则相对表现出较好的抑菌效果。     

Evaluation of a Cow-Side Test for Detection of Gram-Negative Bacteria in Milk from Cows with Mastitis

Waage, S., P. Jonsson and A. Franklin: Evaluation of a cow-side test for detection of Gram-negative bacteria in milk from cows with mastitis. Acta vet. scand. 1994, 207-211.– A modified Limulus amebocyte lysate (LAL) cow-side test was evaluated under field conditions. The principle of the test is to visualize reactions between test components and endotoxin from the cell wall of Gram-negative bacteria. The practical purpose is to detect such bacteria in mastitic milk. Secretions from 789 udder quarters with clinical mastitis were examined by the LAL-test. Parallel quarter milk samples were sent to a mastitis laboratory for microbiological examination. Eleven veterinary surgeons in three veterinary districts in Norway performed the field investigations. Results of the LAL-test and culture agreed in 93% of all milk samples tested, agreement measured by kappa being 0.63. The sensitivity of the test in detecting Gram-negative bacteria was 63%, while the specificity was 97%. The predictive value of a positive test result was 70%, the figure being somewhat higher (75%) when the material was limited to milk samples without antibiotic residues. The predictive value of a negative test result was 95%. The LAL-test is considered to constitute a valuable cow-side test for the veterinary practitioner, aiding the selection of antibacterial drug of choice for the initial treatment of clinical mastitis.