A case-control study of Nocardia mastitis in Ontario dairy herds

A case-control study was conducted to identify milking hygiene and udder therapy factors associated with a diagnosis of Nocardia mastitis in dairy herds from which milk samples are submitted to the Ontario Ministry of Agriculture and Food, Veterinary Laboratory Services, Guelph laboratory. The data were collected by telephone interview from 31 case and 31 control herds.

After analytical control for confounders, blanket dry cow therapy and a dry cow antibiotic product were associated with a diagnosis of Nocardia mastitis in a herd, whereas another dry cow antibiotic product had a sparing effect.

In comparison to mastitis pathogens susceptible to dry cow antibiotic therapy, Nocardia species were isolated infrequently from milk specimens submitted to the Guelph mastitis laboratory.

     

Isolation and Identification of Pathogenic Bacteria Causing Dairy Cow Mastitis in Liaoning and Drug Sensibility Test of Pathogenic E.coli

In order to understand the main bacterial pathogen species causing dairy cow mastitis in Liaoning, as well as the characteristics of drug sensitivity of the pathogenic E.coli,the milk samples from 75 dairy cows with clinical manifestations for mastitis in certain large-scale dairy farm in Liaoning were collected.The bacteria in milk were cultured and isolated with biochemical methods and in vitro drug sensitivity tests were processed with the isolated E.coli strains.The results showed that the main bacterial pathogen for dairy cow mastitis were E.coli（separation rate 58.7%),S.aureus（64.0%）and S.agalactiae（54.7%),and multiple infection including double and triple infection were identified.The drug sensitivity tests on the isolated E.coli indicated that the E.coli isolates were highly resistant to sulfonamides（resistance rate>85%）and chloramphenicol（resistance rate>30%),and they were relatively low resistant to ampicillin（9.5%),ciprofloxacin（9.5%),ceftiofur（7.1%）and ofloxacin（4.8%).The results was able to provide reliable theoretical basis for prevention and control of dairy cow mastitis in Liaoning area.     

辽宁地区奶牛乳房炎细菌性病原分离鉴定及大肠杆菌药敏试验

为了掌握辽宁地区奶牛乳房炎主要细菌性病原种类及致奶牛乳房炎大肠杆菌药物敏感性特征,本研究选取辽宁地区某大型奶牛场75头临床表现为乳房炎的奶样进行细菌培养与分离,通过生化方法对分离到的细菌进行鉴定,并对分离到的奶牛源大肠杆菌进行体外药物敏感性试验研究。结果发现,该场奶牛乳房炎细菌性病原主要为大肠杆菌、葡萄球菌和链球菌,其检出率分别为58.7%、64.0%和54.7%,存在二重感染和三重感染等混合感染的情况。大肠杆菌药物敏感性试验结果表明,该场分离株对磺胺类药物（耐药率>85%）及氯霉素类药物（耐药率>30%）耐药性较高,对氨苄西林（9.5%）、环丙沙星（9.5%）、头孢噻呋（7.1%）和氧氟沙星（4.8%）比较敏感。上述研究结果为该地区奶牛乳房炎的防制提供可靠的理论依据。     

Feline T-Lymphotropic Virus (FTLV) (Feline Immunodeficiency Virus Infection) in cats in New Zealand

AIM: To identify and enumerate colony forming units (cfu) of mastitis pathogens in bulk tank milk (BTM) from pasture-fed New Zealand dairy cows in the Waikato region.

METHODS: BTM samples from seven seasonal-calving dairy herds in the Waikato region were collected monthly from August to December 2004 (cows calved during July-September). Milk samples were cultured on blood aesculin and MacConkey agar plates for 24 h, and the number of mastitis pathogens identified and counted.

RESULTS: Colonies identified in BTM included aesculinpositive streptococci, Staphylococcus aureus, coagulase-negative staphylococci (CNS), and coliforms; counts ranged from zero to >1,000 cfu/ml. Counts >1,000 cfu/ml for total aesculin-positive streptococci, CNS and coliforms were present in 48%, 51% and 11% of BTM samples, respectively. Counts of Staph. aureus ranged from zero to 1,000 cfu/ml, but first appeared in BTM samples only in October. Staphylococcus aureus was repeatedly isolated in BTM from 4/7 farms during the testing period.

CONCLUSIONS: Counts of mastitis pathogens in this study appeared high relative to interpretive criteria set by other workers, which may indicate a high prevalence of mastitis risk factors on these farms. Interpretation of results is difficult as aesculinpositive streptococci, CNS and coliforms can be isolated from the environment as well as from cows with clinical or subclinical mastitis. Furthermore, Staph. aureus is inconsistently excreted from infected bovine mammary glands. More extensive study of this method is required in New Zealand to attempt to further validate the interpretation of results of bacterial culture of BTM.

CLINICAL RELEVANCE: This method may be used to monitor challenge from mastitis pathogens over time as part of milk quality control programmes. The technique may be of use as a screening test to provide information to veterinarians, affording them the opportunity to have an input into mastitis control on dairy farms in New Zealand.     

Udder health and risk factors for subclinical mastitis in organic dairy farms in Switzerland

A study was performed in 1997 to estimate the prevalence and to investigate the etiology of subclinical mastitis in Swiss dairy herds managed under guidelines of controlled organic farming. It was planned as a longitudinal study over a period of 1 year and included a stratified random sample of 152 certified organic farms and 1907 cows. Two farm visits (the first from June to October when cows were on pasture, the second from January to March when cows were confined to barns) were performed on each farm. At each visit, farm management and individual-cow data (with emphasis on milking procedures and udder sanitation) were recorded. California mastitis tests (CMTs) were performed on each udder quarter of all cows in lactation. Milk samples with CMT >1+ were submitted for somatic cell counting (SCC), bacteriological examination and to test for antibiotic susceptibility. The SCC and germ-cell counts of monthly bulk-tank milk samples were available through Dairy Inspection and Advisory Services and milk production data of 567 herd-book cows were available from breeding associations. Possible individual and environmental predictors of subclinical mastitis were identified using logistic models adjusted for clustering of the data at herd and cow levels. Data were analyzed separately for cows from 7 to 100 and from 101 to 305 days post partum. Prevalences of subclinical mastitis at the quarter level were 21.2% for lactation period 7–100 days and 34.5% for 101–305 days post partum. The geometric mean SCC in bulk-tank milk samples was 85.6×10³ cells/ml. Samples at 7–100 and 101–305 days post partum were positive for Staphylococcus aureus in 16.0 and 7.4%, for coagulase-negative Staphylococci in 51.5 and 50.6%, for Streptococcus agalactiae in 0.0 and 0.8%, for other Streptococci in 19.4 and 15.6%, for E. coli in 1.0 and 0.4%, and for Corynebacterium bovis in 25.7 and 45.1%, respectively. Risks of subclinical mastitis increased significantly with increasing days post partum and advancing age of cow. Cows that were sampled when staying in alpine dairies had considerably higher risks of subclinical mastitis than cows staying in home barns. Significantly lower risks of subclinical mastitis were observed in farms where CMT was performed regularly as a control measure. Bacteria in milk from cows with mastitis exhibited antibiotic resistance at a comparable frequency as found previously in conventional farms.     

奶牛乳房炎溶血性病原菌分离培养及药敏试验

本试验旨在确定吉林市某奶牛场奶牛乳房炎的主要致病菌及致病菌对某些抗生素的敏感性。无菌采集奶牛乳房炎病例的奶样,进行细菌分离培养和细菌的药敏试验。试验结果显示,该奶牛场奶牛乳房炎的主要致病菌为2种溶血性的链球菌,分别是α溶血性链球菌和β溶血性链球菌,且致病菌的耐药性较强,对大多数抗生素均有耐药性。试验结果表明,该奶牛场奶牛乳房炎致病菌具有强致病性和耐药性。     

Quarter,cow, and farm risk factors for intramammary infections with major pathogens relative to minor pathogens in Thai dairy cows

A cross-sectional study was carried out from May to September 2011 on 35 smallholder dairy farms in Chiang Mai, Thailand, to identify the quarter, cow, and farm factors that relate to intramammary infections (IMI) from major specified pathogens, compared to infections from minor pathogens. Data on general farm management, milking management, and dry cow management were recorded for each herd. Quarter milk samples were collected from either clinical or subclinical mastitis quarters. Dependent variables were binary data defining the specified major pathogens, including Streptococcus agalactiae (7.1 %), Streptococcus uberis (9.4 %), Streptococcus dysgalactiae (4.0 %), and other streptococci (16.7 %), as a case, and all minor pathogens as a control, in each dependent variable. The occurrence of S. agalactiae IMI was lower in first-parity cows and cows with short milking time. Cows with body condition score (BCS) <2.5 had higher occurrence of S. agalactiae IMI. The occurrence of S. uberis IMI was higher in quarters with California mastitis test (CMT) score 2, score 3, and having clinical mastitis and in farms with increasing age of vacuum system. Quarters with CMT score 3, having clinical mastitis, cow with manual milking after detaching milking cluster, and farms with high bulk milk somatic cell counts (BMSCC >500,000 cells/ml) had higher occurrence of S. dysgalactiae IMI. For other streptococci, quarters having clinical mastitis, BCS <2.5, and pulling down of milking cluster while milking increased occurrence of other streptococci IMI relative to minor pathogen IMI. These results highlight the importance of individual cow factors, milking characteristics, and BMSCC in determining the risk of IMI from major pathogens.     

The incidence and aetiology of clinical bovine mastitis on 14 farms in Northland,New Zealand

AIM: To estimate the incidence of clinical mastitis and the frequency of isolation of mastitis-causing organisms from clinical cases in one lactation season (July 2005 to May 2006) on 14 dairy farms from the Northland region of New Zealand.

METHODS: Cases of clinical mastitis were determined by trained farm personnel who recorded the identity of affected cows. Pooled milk samples from affected quarter(s) were aseptically collected by the farm personnel, for microbiology. Mean numbers of affected cows and quarters were compared at the population and farm level per 305 cow-days-at-risk (DAR).

RESULTS: One or more cases of clinical mastitis occurred in 559/3,765 (14.8%) lactating cows. The average incidence of clinical mastitis was 0.19 cases per 305 DAR. The incidence in rear quarters (56.2%) was 1.3 times (p=0.027) that of front quarters (43.8%). The incidence of clinical mastitis and numbers of affected quarters were signifi cantly infl uenced by the stage of lactation (higher in early lactation), age (higher in older cows) and farm. At the cow level, the most common isolates were Staphylococcus aureus (23.7%) and Streptococcus uberis (23.3%). No causative organisms were identifi ed in 19.9% of the samples. Each cow had an average of 1.8 quarters affected during a case of clinical mastitis.

CONCLUSIONS: This study demonstrated a higher incidence of staphylococcal clinical mastitis on dairy farms from Northland than has been reported in other regions of New Zealand.     

Prevalence and Determinants of Mastitis and Milk‐borne Zoonoses in Smallholder Dairy Farming Sector in Kibaha and Morogoro Districts in Eastern Tanzania

A study was carried out to establish the prevalence and determinants of mastitis and milk‐borne zoonoses in smallholder dairy farms in Kibaha and Morogoro districts (Tanzania). A total of 57 herds comprising 114 milking cows in Kibaha and 48 herds consisting of 96 milking animals in Morogoro were included in the study. A questionnaire survey was used to assess the socio‐economic determinants of mastitis, whereas California mastitis test (CMT) and microbiological assessment of milk was carried out to establish the status of mastitis and responsible aetiological agents. Seroconversion for brucellosis was evaluated using enzyme‐linked immunosorbent assay (ELISA). Animals were also tuberculin‐tested using a single comparative intradermal method and milk samples were cultured for isolation of Mycobacterium species. Based on CMT, the cow‐based prevalence of subclinical mastitis was 82.4% in Kibaha and 62.4% in Morogoro. Of the 919‐quarter milk samples cultured, 8.2% were positive for aerobic bacteria with predominant isolates being Staphylococcus epidermidis (2.8%), Staph. aureus (1.7%), Streptococcus agalactiae (1.2%) and Staph. intermedius (1.1%). There was a strong association between CMT positivity and bacteriological isolation [relative risk (RR) = 2.60; P = 0.02]. Fungal growth was observed in 21.8% (n = 881) of the samples and the isolates were yeast (19.2%), Mucor (2.5%) and Aspergillus (0.1%). Bucket feeding of calves was associated with increased risk of a quarter being CMT positive (RR = 1.24; P = 0.000), while residual calf suckling was associated with decreased risk of positivity (RR = 0.86; P = 0.015). Earth floor was associated with increased risk of CMT positivity at quarter level (RR = 1.13; P = 0.041) and Jersey breed was identified as a risk factor to mastitis. The prevalence of bovine tuberculosis was 0.4% (n = 259) and 1.7% (n = 181) in Kibaha and Morogoro, respectively. Similarly, the prevalence of brucellosis was 1% (n = 208) in Kibaha and 1.9% (n = 104) in Morogoro. Findings from this study have demonstrated a high prevalence of subclinical mastitis and existence of health risks to milk consumers despite the low prevalence of tuberculosis and brucellosis in the study herds.     

Epidemiological Study of Non‐contagious Intramammary Infections in Nine Commercial Dairy Herds following a Staphylococcus aureus Control Programme

Changes in prevalence in intramammary infection, by pathogen type, in herds applying a stringent contagious mastitis control programme was studied. Enrollment of 1651 lactating cows and collection of milk samples was made in this ancillary study to a cohort study of the dynamics of mastitis prevalence after adoption of a strict contagious mastitis control programme that targeted the elimination of mastitis caused by Staphylococcus aureus. Nine commercial dairies in Italy were used. Aseptic collection of milk samples from all lactating cows was performed at the time of enrollment, from all cows within 7–14 days of entering the lactating herd after the date of enrollment, and from all lactating cows at 2, 4, 7, 10 and 14 months after the date of enrollment. Prevalence of intramammary infection by pathogen type was determined from culture of milk samples. Application of the strict contagious mastitis programme did not lead to an increased risk of non‐contagious mastitis. The risk of coliform, environmental streptococcal and coagulase‐negative staphylococcal intramammary infections decreased after adoption of the programme. The data reported herein indicate that the overall risk for any intramammary infections decreases with adoption of a strict contagious mastitis programme, and that such a programme therefore does not necessarily lead to an increase in environmental mastitis.     

Culture results from milk samples submitted to veterinary diagnostic laboratories from August 2003 to December 2006 in New Zealand

Abstract

AIMS: To determine the pattern of isolation of major mastitis-causing organisms isolated from milk samples submitted to five veterinary diagnostic laboratories in New Zealand.

METHODS: The culture results of 25,288 milk samples that were collected from dairy cows throughout New Zealand from August 2003 to December 2006 and submitted to a group of veterinary diagnostic laboratories were assembled, reviewed and summarised. Logistic regression was used to analyse the effect of year, region (i.e. North vs South Island), and season on the probability of isolating the two most common organisms.

RESULTS: The most commonly isolated mastitis causing organisms from all samples were: Streptococcus uberis (23.6%), Staphylococcus aureus (23.5%), coagulase-negative staphylococci (CNS; 7.2%), Strep. dysgalactiae (6.2%), Bacillus spp. (4.0%), and coliforms (3.7%). The percentage of samples with isolates of Strep. uberis or Staph. aureus was affected by island, year and season (p<0.001). For most of the year, except in late winter and early spring when Strep. uberis was much more common, the percentage of isolates of Strep. uberis and Staph. aureus were not apparently different despite the former being an environmental pathogen and the other a contagious one.

CONCLUSION: The pattern of isolation of major mastitis-causing organisms, as determined from culture of milk samples submitted to diagnostic laboratories in New Zealand, has changed significantly over the last 40 years, with a substantial increase in the percentage of isolates that are Strep. uberis and a decrease in isolates of Strep. agalactiae. There is a clear seasonal pattern to the isolation of both Strep. uberis and Staph. aureus, particularly the former.

CLINICAL RELEVANCE: Knowledge of the aetiological agents causing bovine mastitis on a farm is of value in determining the choice of treatment. This dataset shows that, although there is seasonal pattern to the isolation of mastitis-causing organisms in New Zealand, both Strep. uberis and Staph. aureus are isolated throughout the year, so bacteriology is of value in determining aetiology even in late winter/early spring.     

Comparison of the epidemiological behavior of mastitis pathogens by applying time-series analysis in results of milk samples submitted for microbiological examination

The objective of this study is to examine and compare the trends of mastitis pathogens in quarter milk samples (n?=?240,232) submitted for microbiological examination at the Milk Analysis Laboratory (L.I.G.A.L.) at Galicia, Spain from June 2005 to September 2011. Autoregressive Integrated Moving Average (ARIMA) models and multivariate statistical techniques such as Cluster Analysis were used in order to detect seasonal trends and similarities between the series trends and to classify mastitis pathogens into relatively homogeneous groups. The decrease of bulk milk somatic cell counts achieved by the mastitis control program, developed in recent years in this region, is the result of the decrease in IMI caused by a limited number of mastitis pathogens. The obtained results reflect a greater complexity in the behavior of mastitis pathogens, unlike the traditional classification into contagious or environmental. Staphylococcus aureus showed a trend similar to Streptococcus dysgalactiae, a mastitis pathogen can behave in both a contagious and an environmental manner. Among the traditionally considered environmental mastitis pathogens, Strep. uberis showed a different behavior to Escherichia coli and Klebsiella pneumoniae. Coagulase-negative staphylococci (CNS) species and Streptococcus other than Strep. agalactiae showed differences in the trend model. Time-series analysis and multivariate statistical techniques, such as Cluster Analysis, could be powerful tools to assess the isolation trend of mastitis pathogens because of their ability to cope with stochastic dependence of consecutive data. Furthermore, they could be used to identify the epidemiological behavior of mastitis pathogens using the results of milk samples submitted for routine microbiological examination, by classifying them into relatively homogeneous groups.     

Milk protein profiles in response to Streptococcus agalactiae subclinical mastitis in dairy cows

The objective of this study was to investigate the milk protein profiles of normal milk and those of milk during the course of subclinical mastitis, caused by natural Streptococcus agalactiae infection. Two‐dimensional gel electrophoresis and liquid chromatography mass spectrometry were used to assess protein profiles and to identify the proteins. The results showed that S. agalactiae subclinical mastitis altered the protein profiles of milk. Following Mascot database matching, 11 and 12 protein types were identified in the milk collected from healthy and S. agalactiae subclinical mastitic udders, respectively. The distinct presence of the antibacterial protein cathelicidin‐1 was detected in infected milk samples, which in turn was highly correlated to the severity of subclinical mastitis as represented by the milk somatic cell count (r = 0.616), but not the bacterial count. The protein profile of milk reveals changes in the host response to S. agalactiae intramammary infection; cathelicidin‐1 could therefore serve as a biomarker for the detection of subclinical mastitis in dairy cows.     

Loss in milk yield and related composition changes resulting from clinical mastitis in dairy cows

Relationships between clinical mastitis and milk yield and composition in dairy cows were reviewed. Requirements for inclusion were: data had to be collected after 1975; dependent variables for milk yield and milk composition had to be defined at the cow level; mastitis cases had to be defined by clinical signs, and at least 250 lactations had to be considered. Twenty studies dealing with milk-yield loss and, for four of them, also with related composition changes were selected. Study populations, design of data collection, and analysis methods differed widely between studies. As expected from these differences – but also due to structural-variation factors such as type of pathogen, animal and production level – estimates for milk-yield losses differed in average magnitude and pattern. Literature data regarding changes in milk-fat % and total-protein % changes were contradictory. Critiques of materials and methods allowed us to propose some final recommendations for values to be used as basic inputs in economic calculations of losses caused by mastitis.     

不同地区3个奶牛场临床型乳房炎细菌病原种类分析

本试验通过对不同地区3个奶牛场临床型乳房炎细菌病原的分离鉴定,分析其种类和感染情况,并结合牧场环境状况和管理方式,提出控制乳房炎的建议.从中国福建、新疆、重庆3个不同规模化奶牛场采集61份临床型乳房炎乳样,采用传统微生物鉴定方法与PCR技术进行细菌分离鉴定.结果表明,61份临床型乳房炎乳样中单一感染44份(72.13%),混合感染15份(24.59%);共分离到细菌80株,经传统微生物鉴定方法与PCR技术鉴定主要为大肠杆菌、葡萄球菌和链球菌,其中传染性微生物13株(16.25%)、环境性微生物46株(57.50%)、机会性微生物11株(13.75%)、其他微生物10株(12.50%);3个奶牛场临床型乳房炎仍以单一感染为主,混合感染占有一定的比例,传染性致病菌和环境性致病菌为主要致病菌.在实际生产中,规模化牧场可以通过对乳房炎病原菌的分离鉴定来摸清牧场奶牛乳房炎的感染情况和致病菌种类,结合生产实际有助于了解牛群管理情况,发现问题并加以改善,更好的控制乳房炎的发生.     

Analysis of Clinical Mastitis Pathogenic Bacterial Species in Three Dairy Farms of Different Areas

In order to control mastitis,clinical mastitis pathogenic bacterial species of three dairy farms in different areas were isolated and identified.The types and infection condition of pathogenic bacteria,environmental conditions and management methods of the farms were analyzed.61 clinical mastitis milk samples from three different large-scale dairy farms in Fujian,Xinjiang,and Chongqing were collected for bacterial isolation and identification using traditional microbial identification methods and PCR technology.Among clinical mastitis milk samples collected in this trial,single infection sample was 44 (72.13%)and mixed infections sample was 15 (24.59%).80 bacteria were isolated,mainly E.coli,Staphylococcus and Streptococcus,including 13 strains of infectious microorganisms (16.25%),46 strains of environmental microorganisms (57.50%),11 strains of chance of microorganisms (13.75%),10 strains of other microorganisms (12.50%).Clinical mastitis in three dairy farms were still given priority to single infection,and mixed infection occupies certain proportion,with infectious pathogens and environmental pathogens as the main pathogenic.In the actual production the dairy cow mastitis infection and pathogen species could be carried out through the isolation and identification of mastitis pathogens in large-scale dairy farms.It was helpful to identify the herd management problems and make improvements to better control the occurrence of mastitis combining with the actual production conditions.     

Prevalence of subclinical mastitis and isolated udder pathogens in dairy cows in Southern Vietnam

Dairy production is not traditional in Vietnam. The farmers have little practical knowledge and udder health control is generally lacking. In order to give the farmers appropriate advice, knowledge about the distribution of udder pathogens is crucial. The aim of the study was to investigate the prevalence of sub-clinical mastitis and to identify udder pathogens isolated from smallholder dairy herds in Southern Vietnam. Twenty farms with a herd somatic cell count (SCC) ranging from low (≤400?×?10³?cells/mL) to high (>400?×?10³?cells/mL) were randomly selected. Milk samples were collected from 458 quarters of 115 clinically healthy cows. SCC was analyzed on farm by a portable cell counter. Bacteriological samples were taken using Mastistrip^© cassettes and sent to Sweden for examination. For all herds the mean herd SCC was 632?×?10³/mL milk. The prevalence of subclinical mastitis at quarter SCC basis was 63.2 % and at cow basis 88.6 %. Only 40 % of all cows were bacteriologically negative in all quarters. Streptococcus agalactiae was the most commonly found bacteria species, isolated from 96 of the 458 quarter samples, in 13 of the 20 farms. The results indicate pronounced subclinical mastitis problems among the dairy cows in this region mainly due to infections with S. agalactiae. The high prevalence of this highly contagious pathogen is probably attributable to the generally poor milking hygiene and low awareness of proper measures to prevent occurrence and spread of udder infections. A strict, targeted action program for the herds in this area is required in order to lower the prevalence of subclinical mastitis.     

牛支原体引起奶牛乳房炎的诊断

牛支原体（Mycoplasma bovis）是引起成年牛乳房炎和犊牛肺炎、关节炎的主要病原之一。本文从有乳房炎临床症状的奶牛中采集牛奶样本,经细菌培养和支原体培养、特异性PCR与环介导等温扩增（LAMP扩增）和16S rRNA测序等病原学检测证实为牛支原体感染,同时还有其他细菌的混合感染。     

Udder health in beef cows and its association with calf growth

Background

Studies outside the Nordic countries have indicated that subclinical mastitis (measured by milk somatic cell count or the California Mastitis Test), intramammary infections (IMI), or blind quarters in beef cows may have negative effects on beef calf growth. Knowledge on prevalence of such udder health problems in Swedish beef cows is scarce. Therefore, the main aim of this study was to investigate subclinical mastitis, IMI and udder conformation in a number of beef cow herds. Production of β-lactamase in staphylococci was also investigated. Associations between certain cow factors and subclinical mastitis and IMI, and associations between cow and calf factors and 200 day calf weaning weight were also studied. The herds were visited once within a month after calving and once at weaning. Udder examination and quarter milk sampling, for somatic cell count and bacteriology, were performed in 8 to 12 cows per herd and occasion.

Results

Approximately 50%, 40% and 10% of the cows had subclinical mastitis, IMI, and at least one blind quarter, respectively, but the prevalence varied markedly between herds. Intramammary infections (mainly due to staphylococci) were identified in 13-16% of the milk samples. Less than 5% of the staphylococcal isolates produced β-lactamase. Approximately 11% of the cows sampled twice had the same IMI (mostly Staphylococcus aureus) at both samplings. Cow factors of importance for subclinical mastitis and/or IMI were teat and udder shape, breed, parity, presence of blind quarters, and cow hygiene. No significant associations were found between udder health parameters studied and calf weaning weights.

Conclusions

Subclinical mastitis and IMI, but not blind quarters, were common in beef cows, but the prevalence varied markedly between herds. Most IMI were caused by staphylococci and more than 95% of those were sensitive to penicillin. Cows with large funnel-shaped teats or pendulous udder after calving, and cows with blind quarters were at risk of having subclinical mastitis and/or IMI. Poor hygiene was also a risk factor for udder health problems. No significant associations were found between udder health and calf weaning weight. More studies on risk factors are warranted to improve advisory services on awareness and prevention of mastitis in beef cows.     

宁夏部分地区奶牛乳腺炎病原菌的分离鉴定

从宁夏9个县(区)的16个规模化牛场采集327份患乳腺炎奶牛乳样,通过分离培养和生化试验,检出含细菌乳样226份,乳样细菌检出率69.11%(226/327);鉴定出奶牛乳腺炎病原菌5大类9种260株,确认宁夏部分地区奶牛乳腺炎主要病原菌为凝固酶阴性葡萄球菌、停乳链球菌、金黄色葡萄球菌、大肠埃希菌和酵母菌。乳腺炎的发生以单一病原感染为主,占84.96%(192/226);混合感染较少,占15.04%(34/226)。