Serological study of a dairy herd with a recent history of Neospora abortion

HERD HISTORY: A cluster of 19 abortions occurred in April and May 1994 on a seasonal dairy farm of 277 cows in Taranaki. Lesions consistent with neosporosis were seen in several foetuses. The age of the aborting cows ranged from 2 to 12 years. Pregnant rising 2-year-old heifers had been grazed off the main farm on a run-off' until returning in May, when they were replaced on the run-off by the rising l-year-old calves. None of these pregnant heifers aborted. METHODS: Sera were obtained from all calves (n = 32), 32 of 33 pregnant heifers, 59 of 60 3-4 year-old cows and 101 of 150 older cows, plus all cows that had aborted. Sera were tested using an indirect fluorescent antibody assay. Non-aborting cattle sera were screened at 1:400, and further dilutions were tested from 15 aborted cows. RESULTS: The percentages of seropositive cattle were: 32% of the calves, 3% of the heifers, 31% of the younger cows and 27% of the older cows. The proportion of seropositive heifers was significantly lower (p< 0.01) than in the other age classes. There was no significant difference in the proportion of seropositive animals between these other age classes (p >0.05). Of the 15 cows that aborted, and for which further dilutions were tested, nine had titres of 1: 12,800, four had titres of 1:6400, one had a titre of 1: 1600 and one had a titre of 1:400. Twenty cows were the dams of pregnant heifers. Six of these cows were seropositive but all their offspring were seronegative. Fifteen aborting cows were held over to the following year when 13 became pregnant and calved normally. There were only two to three abortions in the whole herd in this following year. CONCLUSION: These results suggest that either a point-infection occurred sometime in early 1994 with an infective period short enough so that the heifers did not get infected when they returned to the main farm, or some factor precipitated a recrudescence of latent infection with a subsequent rise in titres in about 29% of the animals on. the main farm only. Although neither hypothesis can be proven or disproven in this observational study, the former hypothesis seems more likely.     

Age-structured dynamic, stochastic and mechanistic simulation model of Salmonella Dublin infection within dairy herds

In the demand for a decision support tool to guide farmers wanting to control Salmonella Dublin (S. Dublin) in Danish dairy herds, we developed an age-structured stochastic, mechanistic and dynamic simulation model of S. Dublin in dairy herds, which incorporated six age groups (neonatal, preweaned calves, weaned calves, growing heifers, breeding heifers and cows) and five infection states (susceptible, acutely infected, carrier, super shedder and resistant). The model simulated population and infection dynamics over a period of 10 years in weekly time steps as: 1) population sizes of each of the six age-groups; 2) S. Dublin incidence and number of animals in each infection state; and 3) S. Dublin related morbidity and mortality in the acutely infected animals. The effects of introducing one infectious heifer on the risk of spread of S. Dublin within the herd and on the duration of infection were estimated through 1000 simulation iterations for 48 scenarios. The scenarios covered all combinations of three herd sizes (70, 200 and 400 cows), four hygiene levels indicating infectious contact parameters, and four herd susceptibility levels indicating different susceptibility parameters for the individual animals in each of the six age groups in the herd. The hygiene level was highly influential on the probability that the infection spread within the herd, duration of infection and epidemic size. The herd susceptibility level was also influential, but not likely to provide sufficient prevention and control of infection on its own. Herd size did not affect the probability of infection spread upon exposure, but the larger the herd the more important were management and housing practices that improve hygiene and reduce susceptibility to shorten durations of infection in the herd and to increase the probability of extinction. In general, disease and mortality patterns followed epidemic waves in the herds. However, an interesting pattern was seen for acute infections and abortions in adult cattle after the first 2 years of infection in herds with poor hygiene and high susceptibility. Repeated infections in young stock lead to a high proportion of resistant adult cattle, which lead to a dampening effect on acute infections in adults and associated abortions. Sensitivity analyses of 24 alternative scenarios showed that a super shedder state was not essential to mimic the infection dynamics and persistence patterns known from field studies, but a persistent carrier state was required in the model to mimic real life S. Dublin infections.     

Salmonella Typhimurium persistence in a Hunter Valley dairy herd

OBJECTIVE: An epidemiological study was undertaken at a Hunter Valley dairy with persistent Salmonella Typhimurium infection. The aim of the study was to identify cattle currently or previously infected with Salmonella, possible sources of the organism, patterns of spread, and husbandry practices that could be improved. METHODOLOGY: Faecal samples, feed, water and environmental samples were cultured for Salmonella and blood samples were tested for antibodies against Salmonella (Dublin and Typhimurium). A questionnaire was designed to identify possible risk factors associated with Salmonella excretion. RESULTS: S Typhimurium was apparently introduced from an old to a new dairy through manure spread as fertiliser. Salmonella apparently persisted in the effluent pond, and the following year clinical cases occurred after pasture, irrigated with water from the pond, was grazed by dry cows, and adult cattle became clinically ill with salmonellosis. The disease spread to other cows and calves. Poor design of calf pens assisted spread of Salmonella from sick to healthy calves. In addition, there was suspected transmission to the dairy farmer's 9-month-old daughter. Salmonellosis on a farm is a potential zoonotic risk to farm workers and their families. There is also the risk that cull cows may carry Salmonella to the abattoir and subsequently into the human food chain. Methods of waste management, and the design of calf pens, were identified as major risk factors that could be improved to minimise the spread of salmonellosis on this property.     

The specificity of antibody responses in cattle naturally exposed to Fasciola hepatica

Fasciola hepatica causes significant morbidity and mortality in dairy cattle in the Andean region of Cajamarca, Peru, where prevalence of infection of up to 78% has been reported. ELISA and Western blot analyses were used to characterise antibody responses in dairy cattle to adult F. hepatica to excretory-secretory (E/S), somatic (SO) and surface (SU) antigens. Three groups of dairy cattle - calves, heifers and adult cows - naturally exposed to F. hepatica in this region, were monitored every 2 months over a 2-year period. Calves, heifers and adult cows all had antibodies which recognised a 28kDa protein in the SO preparation, whereas only adult cows had antibodies that recognised a 28kDa protein in E/S products. All three groups of cattle responded to a 60-66kDa group of proteins in E/S and SU preparations and a 17kDa antigen in SO products was recognised by antibodies from cows and heifers but not calves. The total antibody response to E/S antigens measured by ELISA, increased over time in calves and remained constantly high over the 2-year period in all three groups of cattle. Slight fluctuations in the antibody response occurred in the group of heifers and cows coinciding with seasonal changes in the level of challenge.     

Seroepidemiology of neosporosis in dairy cattle in Uruguay

A seroepidemiological survey of Neospora caninum was done in a dairy farm in Uruguay employing indirect fluorescent antibody test (IFAT). Sera from 217 cattle (155 cows, 31 heifers and 31 calves) were tested for N. caninum antibodies in July 2000 and it was found that abortions were significantly associated with the seropositivity of the cows by chi(2)-test (P = 0.025). The cows with an IFAT titre of 1:3200 were at a significantly higher risk of abortion than seronegative cows (P = 0.0013). Neospora organisms were detected in the brains of two aborted foetuses by immunohistochemical examination. The infection of N. caninum was considered postnatal because of the even distribution of seropositive cows (60%), low seroprevalence (20%) in calves and no significant correlation in the serostatus between calves and their dams (P = 0.43). A fitted binomial generalised linear model revealed that there was an increasing risk of abortion with increasing IFAT titre and increasing age between 2 and 6 years.     

Analysis of risk factors associated with bovine leukemia virus seropositivity within dairy and beef breeding farms in Japan: A nationwide survey

This cross-sectional study evaluated risk factors associated with farm-level bovine leukemia virus (BLV) seropositivity in 563 dairy and 490 beef farms throughout Japan. Twenty randomly selected cattle on each farm were serologically tested, and farm epidemiologiocal information was obtained through face-to-face interviews. Due to the large number of zero-prevalence dairy and beef farms, data analysis was performed using a zero-inflated negative binomial model, which revealed that the common risk factors associated with higher within-farm seroprevalence were past detection of clinical leukemia and presence of blood-sucking insects. Loose housing on dairy farms and direct contact between calves and adult cattle on beef farms were also identified as risk factors. With regard to farm-level presence of BLV, the presence of purchased cattle was found to be a risk factor in both sectors. Sending heifers to a common ranch was identified as an additional risk factor for dairy farms.     

Prevalence of species and genotypes of Cryptosporidium found in 1-2-year-old dairy cattle in the eastern United States

The prevalence of Cryptosporidium species in 1-2-year-old heifers was determined for 571 animals on 14 dairy farms in seven states on the East Coast of the United States. A fecal specimen collected directly from each heifer was processed to concentrate oocysts that were then examined by polymerase chain reaction (PCR). For every PCR-positive specimen the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified by PCR from heifers on 13 of 14 farms. On all except four farms groups of heifers were housed in a barn or in large covered pens. Others were pastured. From many of the same farms an earlier study reported that 41% of 393 pre-weaned calves and 26.2% of 447 post-weaned calves were infected. In the present study, 11.9% of 571 heifers were infected with Cryptosporidium, 0.7% with Cryptosporidium parvum, the zoonotic species. Of 68 PCR-positive specimens characterized by gene sequencing 1, 4, 10, 24, and 29 calves were infected with Cryptosporidium suis, Cryptosporidium parvum, Cryptosporidium deer-like genotype, Cryptosporidium bovis, and Cryptosporidium andersoni, respectively. These findings demonstrate a lower prevalence of infection in 1-2-year-old dairy cattle than in younger cattle as well as a change in the diversity of species present. Consequently, the risk of humans acquiring infection with C. parvum from exposure to feces from yearling and older cattle appears much lower than from exposure to pre-weaned calves.     

Molecular evidence for zoonotic transmission of Giardia duodenalis among dairy farm workers in West Bengal, India

No study in the past has examined the genetic diversity and zoonotic potential of Giardia duodenalis in dairy cattle in India. To assess the importance of these animals as a source of human G. duodenalis infections and determine the epidemiology of bovine giardiasis in India, fecal samples from 180 calves, heifers and adults and 51 dairy farm workers on two dairy farms in West Bengal, India were genotyped by PCR-RFLP analysis of the β-giardin gene of G. duodenalis followed by DNA sequencing of the nested PCR products. The overall prevalence of G. duodenalis in cattle was 12.2% (22/180), the infection being more prevalent in younger calves than in adult cattle. Zoonotic G. duodenalis Assemblage A1 was identified in both calves and workers although the most prevalent genotype detected in cattle was a novel Assemblage E subgenotype. These findings clearly suggest that there is a potential risk of zoonotic transmission of G. duodenalis infections between cattle and humans on dairy farms in India.     

An estimate of specificity for a Johne's disease absorbed ELISA in northern Australian cattle

Objective To estimate the specificity of an absorbed enzyme-linked immuno-sorbent assay kit^d for Johne's disease (JD) when used in mature cattle populations resident in northern Australia.
Design Blood samples were collected from beef cattle in northern Queensland, the Northern Territory and northern Western Australia, and from dairy cattle in northern Queensland. The specificity of a serological test for JD was estimated by testing the blood samples with an absorbed ELISA kit. Further samples were collected from cattle with positive ELISA results to determine the presence or absence of infection with Mycobacterium avium subsp paratuberculosis .
Procedure During 1995 and 1996, blood, tissue and gut contents were collected from beef cattle at abattoirs in Queensland and the Northern Territory; and blood and faecal samples were collected from dairy cattle in herds assessed to be most at risk for JD in northern Queensland. The blood samples were tested using an absorbed ELISA kit. Tissues and gut contents from beef cattle that had positive ELISA results were cultured for M avium subsp paratuberculosis , and tissues were examined histo-logically. Faecal samples from dairy cattle with positive ELISA results were cultured for M avium subsp paratuberculosis .
Results Estimates of specificity for this absorbed ELISA in mature northern Australian cattle were 98.0% (97.0 to 98.8%, 95% CI) in beef cattle, and 98.3% (96.7 to 99.3%, 95% CI) in dairy cattle.
Conclusion Estimates of specificity in this study were lower for beef cattle from the Northern Territory and northern Western Australia and for dairy cattle from northern Queensland than those quoted from studies on cattle in southern Western Australia. This should be considered when serological testing using the JD ELISA is carried out on northern Australian cattle.     

Study on prevalence of bovine viral diarrhoea virus (BVDV) antibodies in 29 Italian dairy herds with reproductive problems

An epidemiological survey on prevalence distribution of antibodies to BVDV was carried out in dairy cattle herds during 1995-1996 in northern Italy. A total of 704 serum samples from 29 non-vaccinated herds reported to have reproductive problems were tested for serum neutralising antibodies. In each herd, sampling was based on the stratification by age into five classes (< 6 months old calves, 6-12 months old calves, pregnant heifers, uniparous, pluriparous). Overall, 53.3% of samples were serologically positive, with the lowest ratio in 6-12 months old calves (37.9%) and the highest in pluriparous cows (71.2%).     

宁夏地区荷斯坦牛后备牛健康问题及淘汰情况分析

为揭示宁夏地区荷斯坦牛后备牛在周岁前的健康问题和淘汰情况,收集了2013—2020年宁夏地区12 个规模化牧场的后备牛出生记录、健康问题记录和淘汰记录,统计了后备牛周岁前发生的主要健康问题,重点分析了后备牛腹泻和肺炎的发生情况随后备牛月龄和自然月份的关系;此外,还分析了后备牛周岁前的淘汰情况,以及淘汰风险与后备牛月龄和自然月份的关系。宁夏地区的荷斯坦牛中,腹泻和肺炎是后备牛在周岁前最易发生的健康问题,占所有健康问题的75%。后备牛腹泻集中发生在2月龄以内的犊牛中,肺炎病例在周岁前的各生命阶段中均有分布,总体上随着后备牛月龄的增加而减少。不同自然月份中,后备牛腹泻和肺炎的发生情况存在较大差异,腹泻在1~2月发生较多,肺炎在1~6月发病较多,冬季是宁夏地区规模化牧场健康管理的重点季节。周岁前的后备牛淘汰时,其平均淘汰日龄为160.21±110.00 天;随着后备牛月龄的增加,后备牛淘汰风险逐渐降低;不同自然月份中,8~12月淘汰的后备牛较多。结果揭示了宁夏地区荷斯坦牛后备牛周岁前的健康事件和淘汰发生情况,为该地区规模化牧场的后备牛管理提供了有用信息。     

Efficacy of a Neospora caninum killed tachyzoite vaccine in preventing abortion and vertical transmission in dairy cattle

A clinical trial was undertaken to assess the efficacy of Bovilis(?) Neoguard, a killed Neospora caninum tachyzoite vaccine on 5 commercial dairy farms in New Zealand with a history of Neospora-associated abortion. Cattle were enrolled in the trial at 30-60 days of gestation and randomly allocated to treatment or control groups. Treatment consisted of 5 mL doses of Bovilis Neoguard administered subcutaneously at enrolment then 4 weeks later. Isotonic saline was administered to the control group. Of 2246 cattle enrolled in the trial, 10.7% of cows and 12.6% of heifers were seropositive to N. caninum. Sampling of a randomly selected proportion of enrolled animals 6 weeks after the second treatment showed that 188/232 (81.0%) vaccinated with Bovilis(?) Neoguard had seroconverted, while 11/130 (8.5%) cows and 10/36 (27.8%) heifers in the control group had seroconverted. Forty-eight vaccinated and 63 control animals aborted. On one farm 12.5% of control animals and 6.1% of vaccinated animals aborted (vaccine efficacy 0.61; p=0.03). On another farm with a high level of abortion 8.4% of control animals and 8.7% of vaccinates aborted. On the remaining 3 farms fewer abortions occurred than expected. A modified Poisson regression approach was used to calculate relative risks for abortion and vertical transmission. Overall vaccine efficacy was 0.25 (p=0.12). Heifer replacement calves from the animals enrolled in the trial were sampled for antibodies to N. caninum at 6-9 months of age. Fourteen of 17 calves from vaccinated, seropositive cows were seropositive as were 13/23 calves from seropositive cows in the control group. The interaction between dam serostatus and treatment group was significant (p=0.05) with vaccination increasing the risk of vertical transmission. It was concluded that vaccination after conception prevented 61% abortions in one of five herds and that vaccination may have increased the risk of early embryonic death.     

Evaluation of antimicrobial susceptibility patterns in Campylobacter spp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States

OBJECTIVE: To describe antimicrobial susceptibility patterns in Campylobacter spp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States. DESIGN: Longitudinal study. SAMPLE POPULATION: 128 farms. PROCEDURE: Samples and data were collected every 2 months from August 2000 to October 2001. Fecal samples were collected from calves and cows. Milk samples were obtained from the bulk tank and milk line filters. Environmental samples were obtained from a water source, feed bunks of lactating cows, and cattle housing areas. Campylobacter identification and antimicrobial susceptibility testing were performed at a central laboratory by use of microbroth dilution with 2 customized antimicrobial susceptibility panels. RESULTS: 460 and 1,570 Campylobacter isolates were obtained from organic and conventional dairy farms, respectively. Most isolates from both farm types were susceptible to most antimicrobial agents tested, and antimicrobial susceptibility of conventional dairy isolates was decreased, compared with organic dairy isolates. Low proportions of isolates resistant to ampicillin (< 10%) and moderate proportions resistant (30% to 60%) to kanamycin, sulfamethoxazole, and tetracycline were observed on both farm types. The proportion of isolates resistant to tetracycline was higher for conventional than organic farms. CONCLUSIONS AND CLINICAL RELEVANCE: Campylobacter isolates from dairy cattle and farms managed organically and conventionally had similar patterns of antimicrobial resistance; the proportion of resistant isolates was higher for conventional than organic farms.     

Suspected botulism in three intensively managed Australian cattle herds.

Serious outbreaks of a paralytic disease in cattle occurring in the spring and summer of 1988 were investigated on three farms in south eastern Queensland, Australia. On one farm 237 (31 per cent) of 770 cattle died, on the second 109 (40 per cent) of 271 cattle died and on the third 30 (8 per cent) of 380 cows died. Botulism was suspected on the basis of the clinical signs, the lack of significant pathology, a failure to incriminate other agents and a positive feeding trial in one sheep. Laboratory tests for the presence of botulinum toxin failed to confirm this diagnosis, and further feeding trials using ingredients of two rations were also negative.     

Prevalence, incidence, signs and treatment of clinical listeriosis in dairy cattle in England

The prevalence, incidence and clinical signs of listeriosis in dairy cattle in England were investigated by means of a postal questionnaire survey of 1500 dairy farmers. The response rate was 64.1 per cent. Overall the farm prevalence of listeriosis was 11.7 per cent, 9.3 per cent for milking cows, 5.0 per cent for replacement heifers and 1.4 per cent for dairy calves. The within-herd incidence rate per thousand animal-years was 51.4 for all cases, 39.7 for milking cows, 86.6 for replacement heifers and 73.7 for dairy calves. Most cases of clinical listeriosis were reported between December and May, and the most common signs were silage eye, followed by nervous signs. The results of the questionnaire were validated internally by re-estimating the farm prevalence by including only those cases diagnosed by a veterinarian or veterinary investigation centre; the prevalence did not change significantly. The proportion of cases which were culled or died of encephalitic listeriosis was compared with the proportion diagnosed during statutory BSE reporting. The fact that the two proportions were similar provided external validation for the results of the questionnaire.     

Preliminary studies on enzootic bovine leukosis in Saudi dairy farms

The occurrence of sporadic cases of enzootic bovine leukosis in commercial dairy farms in Saudi Arabia was recently confirmed and found to be associated with importation of breeding heifers. Immunodiffusion test was applied to screen the prevalence of infection with bovine leukemia virus among local traditional and dairy cattle. All the 102 examined local cattle were negative, while out of the 1329 tested dairy animals (originating from 23 farms), 268 (from 16 farms) showed precipitating activity. As an epizootiological model, all animals of an infected dairy farm were serologically examined. Out of the 560 originally imported cows and the 1849 animals born locally in the farm, 217 (39%) and 468 (25%) animals, respectively, were found positive. The correlation between the age of locally born animals and the occurrence of antibodies against bovine leukemia virus was discussed.     

荷斯坦青年牛初次配种妊娠月龄对头胎和二胎产奶量和繁殖性能的影响

旨在研究母牛初次配种妊娠月龄（age at first pregnancy,AFP）对其泌乳性能和主要繁殖性能的影响。本研究以我国北方地区2个规模化奶牛场13 927头荷斯坦母牛（A牧场8 091头,B牧场5 836头）的生产数据为基础,统计了母牛AFP、头胎和二胎的产奶量、产后首次发情时间、首次配种时间和首次受孕时间,然后将母牛根据AFP的早晚（12~19月龄）分为8组,对各试验组母牛的头胎和二胎产奶量和主要繁殖性能的数据进行比较分析。结果表明：1）2个规模化奶牛场荷斯坦青年牛AFP以13和14月龄为主（总占比70.1%）;2）AFP可显著影响荷斯坦青年牛头胎和二胎的305 d产奶量（P<0.05）,其中AFP为14月龄时A牧场头胎和二胎305 d产奶量均最高,分别为15 102和15 534 kg;3）AFP可显著影响荷斯坦青年牛头胎和二胎产后首次发情时间和受孕时间（P<0.05）,AFP为14月龄时头胎产后首次发情和受孕情况最优;4）对于产后首配时间,除A牧场头胎AFP为16月龄时产后首次配种时间显著高于AFP为17月龄时（P<0.05）外,其余各组间均无显著性差异（P ≥ 0.05）,并且各组间配种时间相差≤ 5 d;5）通过对A牧场在场牛（2 703头）与淘汰牛（660头）的AFP记录数据分析发现,在场牛的AFP为14.52月龄,显著高于淘汰牛的AFP（P<0.05）。因此,在北方地区现有的生产管理水平下,14月龄可能是荷斯坦青年牛最适宜的初次配种妊娠月龄,这对我国规模化奶牛场选择荷斯坦青年牛适宜的初次配种月龄具有一定参考价值。     

Sources of variation in reproductive performance in selected herds of beef cattle in north-eastern Australia

This paper contains observations of several sources of variation in reproductive performance on 13 herds of beef cattle in north-eastern Australia. Nearly 15,000 cows were examined, man, on more than one occasion. Variation between herds in pregnancy rate in June or September 1964, was 44 to 75 per cent. Lactating heifers had lower pregnancy rates than lactating cows, which in turn had lower rates than non-lactating animals. Within classes, cows in poor body condition had lower fertility than those in forward-store or fat condition. Losses of calves between pregnancy tests and branding ranged from 6 to 40 per cent in a sample of herds. In herds where year-to-year data were avail-able, the majority of cattle had one calf every two years, or two calves every three years. In one herd, cows that calved before February reared more calves than those that calved later. The main conclusion was that improved nutrition of lactating heifers and cows would be expected to increase pregnancy rates substantially.     

Effect of previous antimicrobial treatment on fecal shedding of Salmonella enterica subsp. enterica serogroup B in New York dairy herds with recent clinical salmonellosis

The association of herd- and sample-level factors with the isolation of Salmonella group B from cattle fecal samples was analyzed. Study farms were 65 dairy herds with a recent history of laboratory-confirmed clinical salmonella infections. Herds were visited once per month for three months to collect data and samples for bacteriological culture. Herd size varied widely from 34 to 3700 total cattle on the farm (median=370). Salmonella serogroup B was isolated from 270 of 2726 samples tested. The predominant serotypes identified were S. Typhimurium and S. Typhimurium var. Copenhagen. Logistic regression was used to analyze the relationship between potential risk factors and isolating Salmonella serogroup B. The only herd-level factor which was significantly associated with fecal shedding was total herd size (hundreds of cattle OR=1.09; 95% confidence interval (CI): 1.05, 1.14). The probability of a positive sample decreased substantially for longer intervals between the initial clinical case and sampling (interval in months OR=0.5; 95% CI: 0.3, 0.6). The presence of diarrhea increased the risk of shedding (OR=2.1; 95% CI: 1.4, 3.0). The effect of recent treatment with antimicrobial agents depended on age group. For heifers and cows, recent antimicrobial treatment increased the probability of isolating Salmonella (heifers OR=11.8; 95% CI: 2.9, 48.8; cows OR=4.1; 95% CI: 2.0, 8.4), but this effect was not statistically significant for calves before weaning. Among animals without recent antimicrobial treatment, preweaned calves were more likely to have positive samples than cows (OR=3.5; 95% CI: 1.8, 6.9; heifers OR=4.7; 95% CI: 2.3, 9.6).     

Association of wild bird density and farm management factors with the prevalence of E. coli O157 in dairy herds in Ohio (2007-2009)

Our objective was to determine the role that European starlings (Sturnus vulgaris) play in the epidemiology of Escherichia coli O157:H7 in dairy cattle. We visited 150 dairy farms in Ohio twice during summer and fall months from 2007 to 2009. Fresh faecal pats from 30 lactating cows were collected during each visit. Information on farm management and environmental variables was gathered through a questionnaire administered to the farm owner. The number of starlings observed on the farm was also recorded. Approximately 1% of dairy cattle and 24% of farms were positive for E. coli O157. Risk factors associated with the presence of E. coli O157 in faecal pats included contact between adult cattle and calves, types or number of ventilation and manure management systems and number of birds per milking cow.