[Investigation of abortions and other animal health problems in relation to vaccination against Bluetongue virus in 2009]

By the distribution of a questionnaire between all Swiss cattle practitioners it was possible to investigate abortions and other animal health problems related to Bluetongue vaccination 2009. The questionnaire helped to obtain plausibility and timely relation of the reported disorders. 58 abortions in cattle and different herd health problems could be examined. Because there is no possibility to show that a vaccination itself leads to an abortion the results of proven causes of abortions prior and after Bluetongue vaccination were compared regarding their diagnosis. Due to the fact that diagnosis and solving rate of abortions did not differ before and after vaccination, the vaccination itself cannot be responsible for the abortions. Evaluation of different herd health problems showed that Bluetongue vaccination was not responsible for these disorders which often existed already prior to vaccination. Herd health problems generally have multifactorial causes what makes it difficult to asses the effect of Bluetongue vaccination in some cases.

Incontinentia lactis: physiology and anatomy conducive to milk leakage in dairy cows

Incontinentia lactis is a possible predisposing factor for an elevated level of intramammary infection. The goal of the present study was to investigate possible causes of incontinentia lactis in dairy cows. Two farms that differed in breed composition, but that had similar average milk yields were studied: herd A, 28 kg/d, 31 Red Holstein cows; and herd B, 26 kg/d, 16 Brown Swiss cows. Herd A was classified into 2 groups: incontinentia lactis (ILA group) and control, whereas herd B was exclusively a control herd. Milk samples that represented foremilk and the main milk fraction were collected during 4 milking sessions. In addition, milk leakage samples from the ILA group were collected at different time intervals from 0 to 5 h before milking. Measurements of the teat, milk flow, fractions of cisternal and alveolar milk, intramammary pressure, and blood oxytocin pattern also were obtained. The ILA cows did not have differences in fat content between milk leakage and cisternal milk fraction. Milk fat content, however, increased during milking in response to continuous milk ejection (1.95, 1.99, and 4.61% for milk leakage, cisternal, and main milk samples, respectively). Teat canals were 9% shorter in the ILA cows, which showed greater milk yield, peak, and average flow rates. Quarter cisternal milk yield of ILA cows tended to be greater (0.50 vs. 0.23 and 0.28 kg for ILA and controls from herds A and B, respectively), whereas percentages of cistern milk and alveolar milk did not differ from controls. The greater pressure in the ILA group, both before and after manual udder stimulation (ILA: 4.0 and 6.4 kPa; control: 2.0 and 5.0 kPa, respectively), could be an important cause for the leakage. Nevertheless, the increase in IMP that occurred after udder preparation affirms that milk ejection occurred in response to the tactile teat stimulation, but not before the onset of leakage. Blood oxytocin concentration in ILA cows was low until the start of udder preparation and increased in response to the milking stimulus (reaffirming the hypothesis that milk leakage occurred in the absence of milk ejection). In conclusion, milk losses by leakage are likely due to the large amount of cisternal milk, which creates pressure and causes leakage, in the absence of milk ejection.

Tritrichomonas foetus: Prevalence study in naturally mating bulls in Switzerland

Switzerland is officially free from bovine Tritrichomonas foetus. While bulls used for artificial insemination (AI) are routinely examined for this pathogen, bulls engaged in natural mating, as well as aborted fetuses, are only very sporadically investigated, indicating that the disease awareness for bovine tritrichomoniasis is low. Natural mating in cattle is becoming increasingly popular in Switzerland. Accordingly, a re-introduction/re-occurrence of T. foetus in cattle seems possible either via resurgence from a yet unknown bovine reservoir, or via importation of infected cattle. The low disease awareness for bovine tritrichomoniasis might favor an unnoticed re-establishment of T. foetus in the Swiss cattle population. The aim of our study was thus to search for the parasite, and if found, to assess the prevalence of bovine T. foetus in Switzerland. We included (1) bulls over two years of age used in natural mating and sent to slaughter, (2) bulls used for natural service in herds with or without fertility problems and (3) aborted fetuses. Furthermore, the routinely examined bulls used for AI (4) were included in this study. In total, 1362 preputial samples from bulls and 60 abomasal fluid samples of aborted fetuses were analyzed for the presence of T. foetus by both in vitro cultivation and molecular analyses. The parasite could not be detected in any of the samples, indicating that the maximal prevalence possibly missed was about 0.3% (95% confidence). Interestingly, in preputial samples of three bulls of category 1, apathogenic Tetratrichomonas sp. was identified, documenting a proof-of-principle for the methodology used in this study.

Genotypes and antibiotic resistance of bovine Campylobacter and their contribution to human campylobacteriosis

Campylobacter jejuni and Campylobacter coli are the most important bacterial causes of human gastroenteritis. Chicken has been recognized as a major source for human infection, whereas cattle might also contribute to a lesser extent. However, there is a paucity of information available regarding Campylobacter in Swiss cattle and their role for human campylobacteriosis. To gain more information on genotypes and antibiotic resistance of bovine C. jejuni and C. coli and on their contribution to human disease, 97 cattle isolates were analysed. Multilocus sequence typing (MLST) and flaB typing were applied and the gyrA and 23S rRNA genes were screened for point mutations responsible for quinolone and macrolide resistance, respectively. A total of 37 sequence types (STs) and 44 flaB types were identified, including two sequence types and five flaB types not previously described. Most common sequence types were ST21 (21%), ST61 (12%) and ST48 (11%). Only one isolate was macrolide resistant while 31% (n = 30) were quinolone resistant. Source attribution indicated chicken as the main source of human infection with cattle being second. In conclusion, cattle should not be underestimated as a potential source of human campylobacteriosis.

PRNP promoter polymorphisms are associated with BSE susceptibility in Swiss and German cattle

BACKGROUND: Non-synonymous polymorphisms within the prion protein gene (PRNP) influence the susceptibility and incubation time for transmissible spongiform encephalopathies (TSE) in some species such as sheep and humans. In cattle, none of the known polymorphisms within the PRNP coding region has a major influence on susceptibility to bovine spongiform encephalopathy (BSE). Recently, however, we demonstrated an association between susceptibility to BSE and a 23 bp insertion/deletion (indel) polymorphism and a 12 bp indel polymorphism within the putative PRNP promoter region using 43 German BSE cases and 48 German control cattle. The objective of this study was to extend this work by including a larger number of BSE cases and control cattle of German and Swiss origin. RESULTS: Allele, genotype and haplotype frequencies of the two indel polymorphisms were determined in 449 BSE cattle and 431 unaffected cattle from Switzerland and Germany including all 43 German BSE and 16 German control animals from the original study. When breeds with similar allele and genotype distributions were compared, the 23 bp indel polymorphism again showed a significant association with susceptibility to BSE. However, some additional breed-specific allele and genotype distributions were identified, mainly related to the Brown breeds. CONCLUSION: Our study corroborated earlier findings that polymorphisms in the PRNP promoter region have an influence on susceptibility to BSE. However, breed-specific differences exist that need to be accounted for when analyzing such data.

Comparison of genetic gains per year for carcass traits among breeding programs in the Japanese Brown and the Japanese Black cattle

The breeding program for beef cattle in Japan has changed dramatically over 4 decades. Visual judging was done initially, but progeny testing in test stations began in 1968. In the 1980s, the genetic evaluation program using field records, so-called on-farm progeny testing, was first adopted in Oita, Hyogo, and Kumamoto prefectures. In this study, genetic trends for carcass traits in these 3 Wagyu populations were estimated, and genetic gains per year were compared among the 3 different beef cattle breeding programs. The field carcass records used were collected between 1988 and 2003. The traits analyzed were carcass weight, LM area, rib thickness, s.c. fat thickness, and beef marbling standard number. The average breeding values of reproducing dams born the same year were used to estimate the genetic trends for the carcass traits. For comparison of the 3 breeding programs, birth years of the dams were divided into 3 periods reflecting each program. Positive genetic trends for beef marbling standard number were clearly shown in all populations. The genetic gains per year for all carcass traits were significantly enhanced by adopting the on-farm progeny testing program. These results indicate that the on-farm progeny testing program with BLUP is a very powerful approach for genetic improvement of carcass traits in Japanese Wagyu beef cattle.

Simulating the impact of four control strategies on the population dynamics of Neospora caninum infection in Swiss dairy cattle

A dynamic deterministic simulation model was developed to assess the impact of different putative control strategies on the seroprevalence of Neospora caninum in female Swiss dairy cattle. The model structure comprised compartments of "susceptible" and "infected" animals (SI-model) and the cattle population was divided into 12 age classes. A reference model (Model 1) was developed to simulate the current (status quo) situation (present seroprevalence in Switzerland 12%), taking into account available demographic and seroprevalence data of Switzerland. Model 1 was modified to represent four putative control strategies: testing and culling of seropositive animals (Model 2), discontinued breeding with offspring from seropositive cows (Model 3), chemotherapeutic treatment of calves from seropositive cows (Model 4), and vaccination of susceptible and infected animals (Model 5). Models 2-4 considered different sub-scenarios with regard to the frequency of diagnostic testing. Multivariable Monte Carlo sensitivity analysis was used to assess the impact of uncertainty in input parameters. A policy of annual testing and culling of all seropositive cattle in the population reduced the seroprevalence effectively and rapidly from 12% to <1% in the first year of simulation. The control strategies with discontinued breeding with offspring from all seropositive cows, chemotherapy of calves and vaccination of all cattle reduced the prevalence more slowly than culling but were still very effective (reduction of prevalence below 2% within 11, 23 and 3 years of simulation, respectively). However, sensitivity analyses revealed that the effectiveness of these strategies depended strongly on the quality of the input parameters used, such as the horizontal and vertical transmission factors, the sensitivity of the diagnostic test and the efficacy of medication and vaccination. Finally, all models confirmed that it was not possible to completely eradicate N. caninum as long as the horizontal transmission process was not interrupted.

Assessment of estrogenic exposure in brown trout (Salmo trutta) in a Swiss midland river: integrated analysis of passive samplers, wild and caged fish, and vitellogenin mRNA and protein

This field study examined the vitellogenin (VTG) biomarker response under conditions of low and fluctuating activities of environmental estrogenicity. The present study was performed on immature brown trout (Salmo trutta) exposed to the small river Luetzelmurg, which is located in the prealpine Swiss midland region and receives effluents from a single sewage treatment plant (STP). To understand better factors influencing the relationship between estrogenic exposure and VTG induction, we compared VTG levels in caged (stationary) and feral (free-ranging) fish, VTG levels in fish from up- and downstream of the STP, and two different methods for quantifying VTG (enzyme-linked immunosorbent assay vs real-time reverse transcription-polymerase chain reaction), and we used passive samplers (polar organic chemical integrative sampler [POCIS]) to integrate the variable, bioaccumulative estrogenic load in the river water over time. The POCIS from the downstream site contained approximately 20-fold higher levels of bioassay-derived estrogen equivalents than the POCIS from the upstream site. In feral fish, this site difference in estrogenic exposure was reflected in VTG protein levels but not in VTG mRNA. In contrast, in caged fish, the site difference was evident only for VTG mRNA but not for VTG protein. Thus, the outcome of VTG biomarker measurements varied with the analytical detection method (protein vs mRNA) and with the exposure modus (caged vs feral). Our findings suggest that for environmental situations with low and variable estrogenic contamination, a multiple-assessment approach may be necessary for the assessment of estrogenic exposure in fish.

Mycoplasma bovis infections in Swiss dairy cattle: a clinical investigation

Mycoplasma bovis causes mastitis in dairy cows and is associated with pneumonia and polyarthritis in cattle. The present investigation included a retrospective case–control study to identify potential herd-level risk factors for M. bovis associated disease, and a prospective cohort study to evaluate the course of clinical disease in M. bovis infected dairy cattle herds in Switzerland. Eighteen herds with confirmed M. bovis cases were visited twice within an average interval of 75 d. One control herd with no history of clinical mycoplasmosis, matched for herd size, was randomly selected within a 10 km range for each case herd. Animal health data, production data, information on milking and feeding-management, housing and presence of potential stress- factors were collected. Composite quarter milk samples were aseptically collected from all lactating cows and 5% of all animals within each herd were sampled by nasal swabs. Organ samples of culled diseased cows were collected when logistically possible. All samples were analyzed by real-time polymerase chain reaction (PCR). In case herds, incidence risk of pneumonia, arthritis and clinical mastitis prior to the first visit and incidence rates of clinical mastitis and clinical pneumonia between the two visits was estimated. Logistic regression was used to identify potential herd-level risk factors for M. bovis infection. In case herds, incidence risk of M. bovis mastitis prior to the first visit ranged from 2 to 15%, whereas 2 to 35% of the cows suffered from clinical pneumonia within the 12 months prior to the first herd visit. The incidence rates of mycoplasmal mastitis and clinical pneumonia between the two herd visits were low in case herds (0–0.1 per animal year at risk and 0.1-0.6 per animal year at risk, respectively). In the retrospective-case-control study high mean milk production, appropriate stimulation until milk-let-down, fore-stripping, animal movements (cattle shows and trade), presence of stress-factors, and use of a specific brand of milking equipment, were identified as potential herd-level risk factors. The prospective cohort study revealed a decreased incidence of clinical disease within three months and prolonged colonization of the nasal cavity by M. bovis in young stock.

Diagnosis and therapy of retained fetal membranes, puerperal metritis and clinical endometritis in cattle: Results of the Online-survey among Swiss practitioners. II. Puerperal metritis and clinical endometritis

The aim of the study was to obtain the diagnostic and therapeutic approach among Swiss practitioners in cows with puerperal metritis and clinical endometritis (part 2). All members of the Association for ruminant health were contacted per email via the newsletter. The survey was completed by 128 veterinarians, partially responded by 140 veterinarians. The following main symptoms of puerperal metritis were stated by the practitioners: purulent vaginal discharge, fever and reduced appetite. A vaginal and rectal examination was performed to diagnose the disease. Usually, an intrauterine treatment with tetracycline or cefapirin was done. Parenteral administration of tetracycline or penicillin was often combined with PGF(2α), NSAIDS or cortisone. Clinical endometritis was also diagnosed by vaginal and rectal examination and the main symptom indicated was purulent vaginal discharge. The therapy consisted of the administration of PGF(2α), uterine infusions predominantly with cefapirin, and rarely with parenteral administration of antibiotics. Further diagnostic tools were not used and normally cows were not rechecked. The success of the therapy of puerperal metritis and clinical endometritis was judged to be satisfactory to excellent.

Diagnosis and therapy of retained fetal membranes, puerperal metritis and clinical endometritis in cattle: Results of the Online-survey among Swiss practitioners. I Retained fetal membranes

The aim of this study was to obtain the diagnostic and therapeutic approach among Swiss practitioners in cows with retained fetal membranes (RFM) (part 1). All members of the Association for ruminant health were contacted per email via the newsletter. The survey was completed by 128 veterinarians, partially responded by 140 veterinarians. The manual removal of the fetal membranes is practiced by 129 of the responding veterinarians. Cows with/without fever are treated usually with intrauterine antibiotics. Cows with RFM with/without fever are most commonly treated parenterally with tetracycline or penicillin. The use of cephalosporins and quinolones in cows with fever is more common than in cows without fever. With the present results of the survey veterinarians should critically question the supposed benefits of the manual removal of the placenta and the use of antibiotics in cows with RFM.

Risk Factors for Whole Carcass Condemnations in the Swiss Slaughter Cattle Population

We used meat-inspection data collected over a period of three years in Switzerland to evaluate slaughterhouse-level, farm-level and animal-level factors that may be associated with whole carcass condemnation (WCC) in cattle after slaughter. The objective of this study was to identify WCC risk factors so they can be communicated to, and managed by, the slaughter industry and veterinary services. During meat inspection, there were three main important predictors of the risk of WCC; the slaughtered animal's sex, age, and the size of the slaughterhouse it was processed in. WCC for injuries and significant weight loss (visible welfare indicators) were almost exclusive to smaller slaughterhouses. Cattle exhibiting clinical syndromes that were not externally visible (e.g. pneumonia lesions) and that are associated with fattening of cattle, end up in larger slaughterhouses. For this reason, it is important for animal health surveillance to collect data from both types of slaughterhouses. Other important risk factors for WCC were on-farm mortality rate and the number of cattle on the farm of origin. This study highlights the fact that the many risk factors for WCC are as complex as the production system itself, with risk factors interacting with one another in ways which are sometimes difficult to interpret biologically. Risk-based surveillance aimed at farms with reoccurring health problems (e.g. a history of above average condemnation rates) may be more appropriate than the selection, of higher-risk animals arriving at slaughter. In Switzerland, the introduction of a benchmarking system that would provide feedback to the farmer with information on condemnation reasons, and his/her performance compared to the national/regional average could be a first step towards improving herd-management and financial returns for producers.

The influence of the rearing period on intramammary infections in Swiss dairy heifers: A cross-sectional study

Healthy replacement heifers are one of the foundations of a healthy dairy herd. Farm management andrearing systems in Switzerland provide a wide variety of factors that could potentially be associated withintramammary infections (IMI) in early lactating dairy heifers. In this study, IMI with minor mastitispathogens such as coagulase-negative staphylococci (CNS), contagious pathogens, and environmentalmajor pathogens were identified. Fifty-four dairy farms were enrolled in the study. A questionnaire wasused to collect herd level data on housing, management and welfare of young stock during farm isitsand interviews with the farmers. Cow-level data such as breed, age at first calving, udder condition andswelling, and calving ease were also recorded. Data was also collected about young stock that spent aperiod of at least 3 months on an external rearing farm or on a seasonal alpine farm. At the quarterlevel, teat conditions such as teat lesions, teat dysfunction, presence of a papilloma and teat lengthwere recorded. Within 24 h after parturition, samples of colostral milk from 1564 quarters (391 heifers)were collected aseptically for bacterial culture. Positive bacteriological culture results were found in 49%of quarter samples. Potential risk factors for IMI were identified at the quarter, animal and herd levelusing multivariable and multilevel logistic regression analysis. At the herd level tie-stalls, and at cow-level the breed category “Brown cattle��� were risk factors for IMI caused by contagious major pathogenssuch as Staphylococcus aureus (S. aureus). At the quarter-level, teat swelling and teat lesions were highlyassociated with IMI caused by environmental major pathogens. At the herd level heifer rearing at externalfarms was associated with less IMI caused by major environmental pathogens. Keeping pregnant heifersin a separate group was negatively associated with IMI caused by CNS. The odds of IMI with coagulase-negative staphylococci increased if weaning age was less than 4 months and if concentrates were fed tocalves younger than 2 weeks. This study identified herd, cow- and quarter-level risk factors that may beimportant for IMI prevention in the future.

A natural freshwater origin for two chlamydial species, Candidatus Piscichlamydia salmonis and Candidatus Clavochlamydia salmonicola, causing mixed infections in wild brown trout (Salmo trutta)

Gill disease in salmonids is characterized by a multifactorial aetiology. Epitheliocystis of the gill lamellae caused by obligate intracellular bacteria of the order Chlamydiales is one known factor; however, their diversity has greatly complicated analyses to establish a causal relationship. In addition, tracing infections to a potential environmental source is currently impossible. In this study, we address these questions by investigating a wild brown trout (Salmo trutta) population from seven different sites within a Swiss river system. One age class of fish was followed over 18 months. Epitheliocystis occurred in a site-specific pattern, associated with peak water temperatures during summer months. No evidence of a persistent infection was found within the brown trout population, implying an as yet unknown environmental source. For the first time, we detected 'Candidatus Piscichlamydia salmonis' and 'Candidatus Clavochlamydia salmonicola' infections in the same salmonid population, including dual infections within the same fish. These organisms are strongly implicated in gill disease of caged Atlantic salmon in Norway and Ireland. The absence of aquaculture production within this river system and the distance from the sea, suggests a freshwater origin for both these bacteria and offers new possibilities to explore their ecology free from aquaculture influences.