A longitudinal study of Escherichia coli O157 in cattle of a Dutch dairy farm and in the farm environment

From July 1999 till November 2000, a longitudinal study was conducted on a dairy farm in The Netherlands to study within herd prevalence and types of verocytotoxin producing Escherichia coli (VTEC) of serogroup O157 over time, and determine environmental reservoirs and possible transmission routes. Faeces, blood, milk and environmental samples were collected 14 times with intervals varying from 4 to 10 weeks during the study period. Faecal samples were selectively cultured for Escherichia coli O157. Isolates were tested by PCR for the most common virulence genes, VTI, VTII and eae, and typed by pulsed field gel electrophoresis. In total, 71 isolates were obtained, of which 49 from dairy cows, 8 from young stock, 5 from other animals and 9 from the environment. Positive samples were all detected in summer and early fall. VT- and eae-genes were found in all tested isolates, except in one. DNA typing showed that three clusters of O157 isolates could be identified. One of these clusters contained samples of two shedding seasons, indicating persistence on the farm during winter and spring. Repeated measures analysis of variance showed that cows with O157 VTEC infection had higher daily milk production in the period preceding sampling (p = 0.0055). There was no significant association between the results of the LPS-ELISA on serum samples from dairy cows and their O157 status.     

Tick-borne fever (Ehrlichia phagocytophila infection) on a dairy farm in Friesland

Disease outbreaks, associated with ixodid ticks, among cows on a dairy farm in Friesland, in the north of the Netherlands, were monitored during the summers of 1996, 1997, and 1998. The most important symptoms were a sudden drop in milk yield, fever, apathy, and problems with locomotion. The diagnosis 'tick-borne fever' was confirmed by finding Ehrlichia phagocytophila inclusion bodies in neutrophils of blood smears from sick animals. Significant economic losses due to the disease were recorded each year. Borrelia burgdorferi, although transmitted by the same tick, did not seem to be involved. Further research on tick-borne fever is of particular relevance in connection with recent E. phagocytophila cases diagnosed in dogs and in a human patient in the Netherlands.     

Anti-Muellerian hormone levels in plasma of Holstein-Friesian heifers as a predictive parameter for ovum pick-up and embryo production outcomes

The aim of this study was to investigate whether plasma anti-Muellerian hormone (AMH) levels of Holstein-Friesian heifers could be used to predict ovum pick-up (OPU) and embryo production outcomes. Plasma samples and data were collected from 64 heifers, which underwent repeated OPU with subsequent in vitro embryo production followed by embryo flushing after superovulation. AMH levels were significantly positively correlated with the number of follicles aspirated per OPU session (r = 0.45), recovered oocytes per OPU (r =0.43) and in vitro produced embryos per OPU (r = 0.28). No significant correlations between AMH and in vivo produced embryos were ascertained. Our results suggest that correlations between AMH and outcomes of an OPU-IVF program are too low to use AMH as a precise predictive parameter for the success of a particular OPU procedure in Holstein-Friesian heifers. However, AMH can help to identify groups of very good or very poor oocyte donors.     

Long-term follow-up of laminin alpha2 (merosin)-deficient muscular dystrophy in a cat

Progressive muscle weakness beginning at 6 months of age was observed in a male Persian-mix cat. Muscle atrophy and joint contracture progressed over the next 3 years. The cat had developed gait difficulty at 8 months of age. The cat died at age of 5 years and 3 months due to an acute respiratory disorder. The clinical, laboratory, necropsy and histopathological findings of the cat were consistent with those of muscular dystrophy. The cat was diagnosed as having laminin alpha2 (merosin)-deficient muscular dystrophy on the basis of immunohistochemical findings. The cat was born in an inbred colony, and another related cat exhibited similar clinical signs. Few cases of laminin alpha2-deficient muscular dystrophy have been reported in cats, and this report provides additional information about the disease.     

An outbreak of dictyocaulosis in lactating cows on a dairy farm

CASE DESCRIPTION: The owner of a herd of 74 Holstein-Friesian cattle reported decreased milk production, weight loss, and coughing among lactating cows. Owner-initiated antimicrobial treatment was unsuccessful; 1 lactating cow died, and 50% of the lactating cows had clinical signs of respiratory distress, such as tachypnea and coughing. CLINICAL FINDINGS: On the basis of history, physical examination findings, and fecal examination results, affected animals were determined to have Dictyocaulus viviparus (lungworm) infestation. The disease history suggested that the herd contained cows with subclinical patent lungworm infestations; after introduction of susceptible heifers, the pastures had become heavily infested with D viviparus and clinical problems subsequently developed in both newly introduced and resident cows. TREATMENT AND OUTCOME: Affected and unaffected heifers and adult cows were treated with a pour-on formulation of eprinomectin (0.5 mg/kg [0.23 mg/lb]). One animal died, but 2 weeks after treatment, clinical signs among affected cattle were markedly improved. Ten weeks after treatment, milk production improved from 23 kg/cow/d (51 lb/cow/d) to 28 kg/cow/d (62 lb/cow/d). CLINICAL RELEVANCE: The outbreak provides additional evidence that dictyocaulosis is becoming more common among adult dairy cattle, rather than almost exclusively affecting young stock. This may be attributable to anthelmintic use and management practices on dairy farms. Combined with anecdotal reports of an increase in the incidence of dictyocaulosis among adult cattle in North America, D viviparus infestation should be included as a differential diagnosis for decreased milk production, weight loss, and coughing among adult dairy cattle.     

Assessing the microbiota of recycled bedding sand on a Wisconsin dairy farm

Background:Sand is often considered the preferred bedding material for dairy cows as it is thought to have lower bacterial counts than organic bedding materials and cows bedded on sand experience fewer cases of lameness and disease.Sand can also be efficiently recycled and reused,making it cost-effective.However,some studies have suggested that the residual organic material present in recycled sand can serve as a reservoir for commensal and pathogenic bacteria,although no studies have yet characterized the total bacterial community composition.Here we sought to characterize the bacterial community composition of a Wisconsin dairy farm bedding sand recycling system and its dynamics across several stages of the recycling process during both summer and winter using 16S rRNA gene amplicon sequencing.Results:Bacterial community compositions of the sand recycling system differed by both seasons and stage.Summer samples had higher richness and distinct community compositions,relative to winter samples.In both summer and winter samples,the diversity of recycled sand decreased with time drying in the recycling room.Compositionally,summer sand 14 d post-recycling was enriched in operational taxonomic units(OTUs)belonging to the genera Acinetobacter and Pseudomonas,relative to freshly washed sand and sand from cow pens.In contrast,no OTUs were found to be enriched in winter sand.The sand recycling system contained an overall core microbiota of 141 OTUs representing 68.45%±10.33%SD of the total bacterial relative abundance at each sampled stage.The 4 most abundant genera in this core microbiota included Acinetobacter,Psychrobacter,Corynebacterium,and Pseudomonas.Acinetobacter was present in greater abundance in summer samples,whereas Psychrobacter and Corynebacterium had higher relative abundances in winter samples.Pseudomonas had consistent relative abundances across both seasons.Conclusions:These findings highlight the potential of recycled bedding sand as a bacterial reservoir that warrants further study.     

Coronavirus as an agent of neonatal calf diarrhea in a Chinese dairy cattle farm.

Neonatal calf diarrhea is a significant health problem in dairy industry in the whole world. Although the aetiological agents of neonatal diarrhea are diverse, it is obvious that viruses play an important role. One of them is bovine coronavirus (BCV). Since BCV was discovered (MEBUS et al., 1969), there have been many published reports describing the virus and its importance in calves. In China, we first investigated the seroepidemiological status of BCV infections in cattle (YAO et al., 1990). The results showed that the incidence of infections with BCV in cattle in different chinese regions are high. Further work on direct diagnosis of BCV as a causative agent of diarrhea was therefore necessary. In the last years we have developed diagnostic methods including a monoclonal antibody-based ELISA to detect BCV and other diarrheal viruses. In this study, the diagnosis of an outbreak of BCV in chinese dairy cattle is described.     

陕西杨凌某种牛场奶牛球虫种类的调查

对陕西杨凌某种牛场荷斯坦奶牛球虫感染情况进行了调查,发现该场犊牛球虫平均阳性率为45.83%(22/48),每克粪便中所含的卵囊数最大值为1 100。共鉴定出8种艾美耳属的球虫,其中亚球形艾美耳球虫(Eim eria subsperica)检出率为31.57%,邱氏艾美耳球虫(E.zuernii)检出率为10.42%,椭圆艾美耳球虫(E.ellips)检出率为8.33%,阿拉巴马艾美耳球虫(E.alabam ensis)检出率为10.42%,牛艾美耳球虫(E.bovis)检出率为22.92%,加拿大艾美耳球虫(E.canadensis)检出率为6.38%,柱状艾美耳球虫(E.cylindrica)检出率为10.42%,奥博艾美耳球虫(E.auburnensis)检出率为4.17%,优势种为亚球形艾美耳球虫和牛艾美耳球虫。     

An epidemic of East Coast fever on a dairy farm in eastern Tanzania

During the period August-September 1995, an epidemic of East Coast fever occurred at a dairy farm in Morogoro region of eastern Tanzania. Due to an intensive dipping scheme since 1970, a very unstable endemic status had been established in the animals. A breakdown in the dipping scheme caused a major disease outbreak; the dip wash was not changed for 18 months prior to the outbreak and dipping continued in a dip wash of unknown strength. There was also a delay in detecting the disease at an early stage. In total, 180 out of 432 (42%) of the cattle at the farm died--resulting in a loss of Tshs. 26,330,000 (US$ 42,879). The attack risk was nearly 77%. The outbreak points to the importance of adopting integrated strategies for the control of ticks and tick-borne diseases.     

First documentation of a neospora-induced "abortion storm" (exogenous transplacental transmission of neospora caninum) in a Swiss dairy farm

In a Swiss dairy farm (canton of Geneva) consisting of 73 animals 8 abortions were observed within 2 weeks. Serological and molecular biological analyses (PCR) on aborting dams, and abortion materials, respectively, revealed that the protozoan parasite Neospora caninum was the causative agent. Besides the 8 aborting animals, 12 other non-aborting heifers were found to be serologically positive for this parasite. All positive sera were further tested in an avidity-ELISA to elucidate the recency of infection. All seropositive animals but one showed low avidities at the time the abortion storm started. This indicated at a recent N. caninum-infection within the herd. Thus, the animals most probably were exposed to N. caninum-oocysts (e.g. by dog feces-contaminated forage) and the resulting abortion storm was due to an exogenous (formerly known as "horizontal") parasite transmission into a naive herd. This is the first documented record of such an event in Switzerland.     

A longitudinal study of Neospora caninum infection on a dairy farm in New Zealand

A 600-cow New Zealand dairy herd experienced an abortion storm in 1997 and was monitored (blood sampling at about 3-month intervals) from May 1997 until January 1999. Abortion risk reached 9% in 1997 and was highest in heifers at 19%. The abortion risk decreased in 1998 to 3.2% (still somewhat higher than during the years prior to the outbreak). The serological reaction pattern for Neospora caninum showed an association with abortion risk only around the time of the 1997 outbreak when seropositive cows were 4.2 times more likely to abort than negative ones. Over the whole study period, only 27% of cows that were sampled on all nine visits always tested negative. Offspring from dams which had positive tests for Neospora caninum were 2.4 times more likely to abort than those from dams testing consistently negative. Controlling for age and breed, seropositive cows produced more milk than those that were consistently negative. Infection might have been present endemically within this herd prior to the epidemic, but in 1997 an additional factor appeared to have triggered the outbreak.     

Impact of foot-and-mouth disease on mastitis and culling on a large-scale dairy farm in Kenya

Foot and mouth disease (FMD) is a highly transmissible viral infection of cloven hooved animals associated with severe economic losses when introduced into FMD-free countries. Information on the impact of the disease in FMDV-endemic countries is poorly characterised yet essential for the prioritisation of scarce resources for disease control programmes. A FMD (virus serotype SAT2) outbreak on a large-scale dairy farm in Nakuru County, Kenya provided an opportunity to evaluate the impact of FMD on clinical mastitis and culling rate. A cohort approach followed animals over a 12-month period after the commencement of the outbreak. For culling, all animals were included; for mastitis, those over 18 months of age. FMD was recorded in 400/644 cattle over a 29-day period. During the follow-up period 76 animals were culled or died whilst in the over 18 month old cohort 63 developed clinical mastitis. Hazard ratios (HR) were generated using Cox regression accounting for non-proportional hazards by inclusion of time-varying effects. Univariable analysis showed FMD cases were culled sooner but there was no effect on clinical mastitis. After adjusting for possible confounders and inclusion of time-varying effects there was weak evidence to support an effect of FMD on culling (HR = 1.7, 95% confidence intervals [CI] 0.88-3.1, P = 0.12). For mastitis, there was stronger evidence of an increased rate in the first month after the onset of the outbreak (HR = 2.9, 95%CI 0.97-8.9, P = 0.057).

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0173-4) contains supplementary material, which is available to authorized users.     

Type-I hypersensitivity as a component of eosinophilic myositis (muscular sarcocystosis) in cattle

Eight bovine hearts with lesions of eosinophilic myositis (EM) and 2 bovine hearts without EM lesions were collected at slaughter. Blood samples from these 10 hearts, and the heart of a newborn calf also were collected. Histologically, Sarcocystis cruzi was identified in the 8 hearts with EM lesions and the 2 hearts without EM lesions, but not in the heart of the newborn calf. Serum was harvested from the 10 blood samples and was used in homologous, modified, passive cutaneous anaphylaxis tests. Antigen was prepared from S cruzi bradyzoites isolated from the 2 hearts without EM lesions. Serum samples from the 8 cattle with EM lesions reacted positively to S cruzi antigen. When heat-inactivated IgE in serum (56 C for 4 hours) was used, all passive cutaneous anaphylaxis responses were considered negative. Using ELISA, serum IgE concentrations from the 10 cattle with and without EM lesions were 2.2 to 9 U/ml. As determined by radial immunodiffusion, IgM concentrations were 80 to 215 mg/dl. Immunoglobulin G concentrations were 420 to 2,050 mg/dl, but most were less than or equal to 1,700 mg/dl. Immunoglobulin A concentrations were 0 to 62 mg/dl; 1 steer with EM lesions had 0 mg/dl. Double-gel immunodiffusion confirmed the presence of Sarcocystis-specific precipitating antibodies. Sera from the 10 cattle with and without EM lesions formed at least 1 precipitin band.     

Serology of a Neospora abortion outbreak on a dairy farm in New Zealand: a case study

AIM: To describe the kinetics of serological titres after an abortion outbreak in April-May 1995 due to Neospora caninum affected 17 dairy cows in a herd of 320. METHODS: Thirty-five cows, that had either aborted, carried mummified calves, were not pregnant or calved normally were: bled several times at regular intervals and the sera tested for Neospora antibodies in the indirect fluorescence antibody test (IFAT). RESULTS: Maximal IFAT titres of up to 1:4000 occurred within 6 weeks of the abortion outbreak, decreased over the next 2 months to < or = 1:200 and remained at this level until the next scheduled bleed a further 2 months later. A rise in titres was subsequently observed in the cows that had aborted or were not pregnant (at the time of the abortions) or had carried mummified foetuses. Seroconversion was also observed in some of the control cows, which had, up until then, remained seronegative. A dog and cat in contact with the cows in the herd investigated were, however, negative in the IFAT. CONCLUSIONS: Maximal serological titres in Neospora abortions are observed within weeks of the abortion event and then quickly return to very low levels. Subsequently, a recrudescence of titres can be observed in infected cows during the next pregnancy, without it being associated with repeat abortions.     

Effects of housing practices on the development of foot lesions in dairy heifers in early lactation

Measurements were made of sole haemorrhages and white line lesions in two groups of heifers which were either introduced to a cubicle house four weeks before they calved (group 1) or housed in a straw yard for eight weeks after calving and then moved into the cubicle house (group 2). The overall severity of the lesions was described by a cumulative score which defined the product of the severity and the area of the overall lesions in each animal. The lesions were scored on six occasions, from four weeks before to 24 weeks after parturition. Before parturition, sole lesions were absent or very small. By four weeks after calving, most of the animals had both types of lesion, but the differences between the two groups were small and statistically insignificant. There were no significant differences in the white line lesions between the two groups at any of the observations. There were, however, progressive, highly significant differences between the two groups in the severity of sole haemorrhages. By 12 weeks after calving, the median score for group 1 was 69 and that for group 2 was 11. In group 2, the sole haemorrhage score peaked at eight weeks but declined thereafter, even though these animals were moved into cubicles eight weeks after calving. By 12 weeks after calving, six of the 17 heifers in group 1 had sole ulcers but none of the 16 in group 2 had ulcers.     

Validation of a commercial ELISA for the detection of bluetongue virus (BTV)-specific antibodies in individual milk samples of Dutch dairy cows

A recently developed indirect ELISA for the detection of bluetongue virus (BTV)-specific antibodies in bovine milk samples was compared to that of the routinely used competitive ELISA on serum samples. During the bluetongue outbreak in the Netherlands in 2006, caused by BTV serotype 8, coupled serum and milk samples were obtained from 470 individual cows from 10 BTV-infected farms with an average seroprevalence of 57%. In addition, bulk milk samples of the same farms, and historically BT-negative samples were tested. Compared to the ELISA for sera, the relative specificity and sensitivity of the ELISA for milk samples is 96.5% and 98.9%, respectively when using a S/P% cut-off value of 50% as advised by the manufacturer. The optimal cut-off value was found at S/P% of 90% revealing an optimal specificity (99.0%) combined with an optimal sensitivity (98.1%). Titres in positive individual milk samples ranged from 1 to 2048 with a peak titre of 128. Bulk milk samples contained antibodies with titres ranging from 64 to 512. The ELISA for milk samples was found to be a reliable and robust test. This diagnostic tool is very useful, and may replace the ELISA for serum samples as first choice in order to get insight into the status of lactating individual animals and therewith of the entire herd with respect to BTV infection.