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In the province of Quebec, Canada, a new regulation restricting usage of antimicrobials of very high importance for human health (Health Canada: category 1 antimicrobials) in production animals is effective since February 2019. The objective of this study was to estimate changes in AM sales in dairy herds after the implementation of the regulation. Therefore, invoice data were extracted from veterinary software, Vet-Expert, used by most dairy veterinarians in the province of Quebec, and antimicrobial quantities were transformed in Canadian defined course doses for cattle (DCDbovCA). The sum of antimicrobials sales monthly in each herd was estimated in DCDbovCA from June 2016 to May 2020. To evaluate the herd-level change in AM sales and the impact of different factors, the number of DCDbovCA by herd from June 2017 to May 2018 (pre-regulation period) were compared with those of June 2019 to May 2020 (post-regulation period). Total category 1 AM sales of 3,569 Quebec's herds went from a range of 14,258 to 21,528 DCDbovCA/month to a range of 1,494 to 4,707 DCDbovCA/month after the implementation of the new regulation. Moreover, using data from 3,337 herds, we estimated a mean (95% confidence interval) reduction in 19 DCDbovCA/herd-year (14.8, 24.2), while the pre-regulation herd-level category 1 AM sales was 26 DCDbovCA/herd-year. This reduction was achieved without evidence of an increase in other antimicrobials. Finally, the veterinary facility associated with the herd was an important determinant of the herd-level reduction in category 1 antimicrobials. This study was the first to quantify a significant reduction in category 1 AM sales following the implementation of a restrictive regulation in dairy production in Canada. These results demonstrate that such an approach is effective to reduce the sales of a specific category of antimicrobial in animal production.

The collective control programmes (CPs) that exist for many infectious diseases of farm animals rely on the application of diagnostic testing at regular time intervals for the identification of infected animals or herds. The diversity of these CPs complicates the trade of animals between regions or countries because the definition of freedom from infection differs from one CP to another. In this paper, we describe a statistical model for the prediction of herd-level probabilities of infection from longitudinal data collected as part of CPs against infectious diseases of cattle. The model was applied to data collected as part of a CP against bovine viral diarrhoea virus (BVDV) infection in Loire-Atlantique, France. The model represents infection as a herd latent status with a monthly dynamics. This latent status determines test results through test sensitivity and test specificity. The probability of becoming status positive between consecutive months is modelled as a function of risk factors (when available) using logistic regression. Modelling is performed in a Bayesian framework, using either Stan or JAGS. Prior distributions need to be provided for the sensitivities and specificities of the different tests used, for the probability of remaining status positive between months as well as for the probability of becoming positive between months. When risk factors are available, prior distributions need to be provided for the coefficients of the logistic regression, replacing the prior for the probability of becoming positive. From these prior distributions and from the longitudinal data, the model returns posterior probability distributions for being status positive for all herds on the current month. Data from the previous months are used for parameter estimation. The impact of using different prior distributions and model implementations on parameter estimation was evaluated. The main advantage of this model is its ability to predict a probability of being status positive in a month from inputs that can vary in terms of nature of test, frequency of testing and risk factor availability/presence. The main challenge in applying the model to the BVDV CP data was in identifying prior distributions, especially for test characteristics, that corresponded to the latent status of interest, i.e. herds with at least one persistently infected (PI) animal. The model is available on Github as an R package (https://github.com/AurMad/STOCfree) and can be used to carry out output-based evaluation of disease CPs. European Food Safety Authority (EFSA)

Mycobacterium avium subsp. paratuberculosis is the etiological agent of Johne’s disease in ruminants. Here, we report the annotated draft genome sequences of 142 M. avium subsp. paratuberculosis strains that were isolated from dairy cattle in France between 2014 and 2018. The genomes of these strains were sequenced using Illumina technology.

The work of ML was supported by the European Union’s Horizon 2020 research and innovation program under Grant No. 734548-ZIKAlliance. Besides, this research received no specific grant from any funding agency, commercial or non-for-profit section.; International audience; The ongoing coronavirus disease 19s pandemic has yet again demonstrated the importance of the human-animal interface in the emergence of zoonotic diseases, and in particular the role of wildlife and livestock species as potential hosts and virus reservoirs. As most diseases emerge out of the human-animal interface, a better understanding of the specific drivers and mechanisms involved is crucial to prepare for future disease outbreaks. Interactions between wildlife and livestock systems contribute to the emergence of zoonotic diseases, especially in the face of globalization, habitat fragmentation and destruction and climate change. As several groups of viruses and bacteria are more likely to emerge, we focus on pathogenic viruses of the Bunyavirales, Coronaviridae, Flaviviridae, Orthomyxoviridae, and Paramyxoviridae, as well as bacterial species including Mycobacterium sp., Brucella sp., Bacillus anthracis and Coxiella burnetii. Noteworthy, it was difficult to predict the drivers of disease emergence in the past, even for well-known pathogens. Thus, an improved surveillance in hotspot areas and the availability of fast, effective, and adaptable control measures would definitely contribute to preparedness. We here propose strategies to mitigate the risk of emergence and/or re-emergence of prioritized pathogens to prevent future epidemics.

Mastitis is a bacterial disease common in dairy farms. Although knowledge about mastitis and its optimal technical management and treatment is now available, some dairy farmers still use antibiotics in inappropriate ways. Antibiotic use by farmers can be influenced by personal restraints and motivations, but it can be assumed that external drivers are also influential. The main purpose of this article is thus to analyse the choices of antibiotic and alternative medicine use for mastitis treatment and investigate the possible influence of two unexplored external drivers in dairy farms: (i) the health advice offered to farmers by farm advisors and veterinarians, (ii) the dairy farming system, as defined by combining the market valuation chosen for the milk, the level of intensification, and the perceived pressure related to investments. Research was based on 51 individual semi-structured interviews with farmers and their corresponding veterinarians and farm advisors. Based on verbatim, the use of antibiotics and alternative medicine by farmers for mastitis treatment, the vet-farmers interactions, and the dairy farming systems are described. The advisory relationships between farmers and farm advisors and between farmers and veterinarians influenced the implementation of selective dry cow therapy, but had very little effect on the use of alternative medicines by farmers, who were more willing to experiment alternative medicines than their advisors. The dairy farming system had very little influence on antibiotic use: some misuse of antibiotics was found whatever the farming system. Systematic dry cow therapy was also a widespread habit in all dairy farming systems except organic. The use of alternative medicine was common in all farming systems.

International audience; Mycobacterium avium ssp. paratuberculosis (MAP) is the etiological agent of paratuberculosis, a disease that affects ruminants worldwide. Despite global interest in the control of this disease, gaps exist in our knowledge of fecal shedding patterns and concurrent serological patterns. This longitudinal study in dairy cattle herds with high MAP seroprevalence in France aimed at accurately describing fecal shedding patterns over 1 year; relating those shedding patterns to individual animal characteristics (age, breed, parity); and exploring the association between fecal shedding patterns and serological patterns. To describe temporal fecal shedding patterns and continuity of shedding, along with the standard quantitative PCR (qPCR) threshold cycle we used a cutoff value that related to low or nonculturable fecal shedding. We also defined a threshold cycle indicative of shedding in high quantities to describe infection progression patterns. Twenty-one herds completed the study, and 782 cows were tested 4 times each. We obtained 4 sets of paired fecal qPCR and serum ELISA results from 757 cows. Although we targeted highly likely infectious animals, we found a large diversity of shedding patterns, as well as high variability between herds in the proportion of animals showing a given pattern. The fecal qPCR results of almost 20% of the final study sample were positioned at least once in the range that indicated low or nonculturable fecal shedding (between the adjusted and the standard cutoff value). Although these animals would typically be classified as non-shedders, they could be important to infection dynamics on the farm. Animals that shed at least twice consecutively and animals that shed in high quantities rarely reverted to negativity. Repeated fecal qPCR can be used to detect temporal fecal shedding traits, and the decision to cull an animal could practically be based on temporal, semiquantitative results. Overall, we found a mismatch between fecal shedding and ELISA seropositivity (637 animals were ELISA-negative 4 times, but only 13% of those animals were qPCR-negative 4 times). We found that having more than 2 ELISA-positive samples was strongly related to persistent and continuous shedding. We suggest that although serological testing is much less sensitive than qPCR, it can also be used, particularly over the course of multiple testing events, to identify animals that are most likely to contribute to the contamination of the farm environment

International audience; Quick detection and recovery of country's freedom status remain a constant challenge in animal health surveillance. The efficacy and cost efficiency of different surveillance components in proving the absence of infection or (early) detection of bluetongue serotype 8 in cattle populations within different countries (the Netherlands, France, Belgium) using surveillance data from years 2006 and 2007 were investigated using an adapted scenario tree model approach. First, surveillance components (sentinel, yearly cross-sectional and passive clinical reporting) within each country were evaluated in terms of efficacy for substantiating freedom of infection. Yearly cross-sectional survey and passive clinical reporting performed well within each country with sensitivity of detection values ranging around 0.99. The sentinel component had a sensitivity of detection around 0.7. Secondly, how effective the components were for (early) detection of bluetongue serotype 8 and whether syndromic surveillance on reproductive performance, milk production and mortality data available from the Netherlands and Belgium could be of added value were evaluated. Epidemic curves were used to estimate the timeliness of detection. Sensitivity analysis revealed that expected within-herd prevalence and number of herds processed were the most influential parameters for proving freedom and early detection. Looking at the assumed direct costs, although total costs were low for sentinel and passive clinical surveillance components, passive clinical surveillance together with syndromic surveillance (based on reproductive performance data) turned out most cost-efficient for the detection of bluetongue serotype 8. To conclude, for emerging or re-emerging vectorborne disease that behaves such as bluetongue serotype 8, it is recommended to use passive clinical and syndromic surveillance as early detection systems for maximum cost efficiency and sensitivity. Once an infection is detected and eradicated, cross-sectional screening for substantiating freedom of infection and sentinel for monitoring the disease evolution are recommended.

M. uberis is an emerging skin pathogen in dairy animals. Its genome underwent massive reduction and gene decay, leading to a minimal set of genes required for an obligatory intracellular lifestyle, which highly resembles the evolution of the leprosy agents M. leprae and M. lepromatosis. The genomic similarity between M. uberis and the leprosy bacilli can help in identifying key virulence factors of these closely related species or in identifying genes responsible for the distinct differences between thelitis or scrotitis and leprosy with respect to clinical manifestations. Specific DNA markers can now be developed for quick detection of this pathogen., Nodular thelitis is a chronic enzootic infection affecting dairy cows and goats. The causative agent was recently shown to be related to the leprosy-causing bacilli Mycobacterium leprae and Mycobacterium lepromatosis. In this study, the genome of this pathogen was sequenced and analyzed. Phylogenomic analyses confirmed that the pathogen present in nodular thelitis and tuberculoid scrotitis is a distinct species related to the leprosy bacilli and Mycobacterium haemophilum. Because the pathogen was originally isolated from a bovine udder, it was named “Mycobacterium uberis.” The genome of “M. uberis” is only 3.12 Mb in length, which represents the smallest mycobacterial genome identified so far but which is close to that of leprosy bacilli in size. The genome contains 1,759 protein-coding genes and 1,081 pseudogenes, indicative of extensive reductive evolution and likely the reason that M. uberis cannot be grown axenically. The pseudogenization and genome reduction in M. uberis seem to have been to some extent independent from the results determined for the genomes of the leprosy bacilli. IMPORTANCE M. uberis is an emerging skin pathogen in dairy animals. Its genome underwent massive reduction and gene decay, leading to a minimal set of genes required for an obligatory intracellular lifestyle, which highly resembles the evolution of the leprosy agents M. leprae and M. lepromatosis. The genomic similarity between M. uberis and the leprosy bacilli can help in identifying key virulence factors of these closely related species or in identifying genes responsible for the distinct differences between thelitis or scrotitis and leprosy with respect to clinical manifestations. Specific DNA markers can now be developed for quick detection of this pathogen.

International audience; Animal health planning activities are not always providing a satisfactory positive impact on herd health and welfare. Moreover, evaluating the impact of advisory programmes is complex due to multiple interacting elements that influence its outcome. Therefore, measuring solely health outcomes is not sufficient: the whole process of the implementation and use of such programmes should be evaluated. In order to evaluate the impact of an intervention with a Herd Health and Production Management (HHPM) programme a process evaluation framework was designed and used. The intervention involved 20 organic dairy cattle farmers and their advisors, in both France and Sweden. In both countries 20 organic dairy farms were selected as control herds. The evaluation of the HHPM programme was based on: (a) the compliance to the programme; (b) the programme's functions influencing herd health management practices and stimulating dialogue between farmers and advisors; (c) its effectiveness in terms of improving herd health compared with control farms. Complete compliance to the programme was fulfilled by 21 out of 40 farmers-advisors. Results from a questionnaire showed that the programme functioned as intended (e.g. by allowing early identification of herd health problems), stimulated change in farmers' herd health management practices and farmer-advisor dialogue. Even though the majority of the users perceived that the programme contributed to herd health improvements, no significant differences in health outcomes were found when compared with control farms 12 months after the start of the intervention. The programme allowed creating an environment promoting the exchange of information between farmers and advisors, necessary to define pertinent advice in a farm-specific situation. Future research should aim at improving methods for the evaluation of the effect of advisory programmes, by identifying early indicators for effective advice and developing methods to evaluate the quality of advisory situations without interfering with them.

Identification of phenotypic traits of resistance to limit MAP spread in a dairy cattle herd using a modelling approach. Society for Veterinary Epidemiology and Preventive Medicine (SVEPM)

Organic dairy farmers must live up to the organic goal of 'good health' in respect the organic principles and regulation. Veterinarians could be the organic dairy farmers' expected sparring partners in reaching this goal but have found difficulties to establish advisory relationships with them. The objectives of this study are -from organic dairy farmers' points of view- (i) to describe farmers' objectives and strategies regarding herd health, (ii) to describe private veterinarians' roles in farmers' animal health promotion strategies and (iii) to identify farmers' reasons for accepting veterinarians in an advisory role. Fourteen organic dairy farmers were interviewed using qualitative research interviews. Data collection and analysis was performed using a modified approach to Grounded Theory. Organic dairy farmers had animal health management strategies focusing on animal health promotion. Veterinarians had most often solely the role of therapist in farmers' animal health management strategies. Reasons explaining that veterinarians were not able to establish advisory roles were found in the differences between veterinarians and farmers regarding their animal health strategies and solutions to disease problems. Furthermore, veterinarians did not always share farmers' (organic) objectives, values and priorities and this could lead to disagreement on the best choice in animal health management practices. This might be further amplified in situations where there exists a lack of dialogue and mutual interest in other.

Since 2007, mortality associated with a previously unreported haemorrhagic disease has been observed in young calves in several European countries. The syndrome, which has been named 'bovine neonatal pancytopenia' (BNP), is characterised by thrombocytopenia, leukocytopenia and a panmyelophthisis. A herd-level case-control study was conducted in four BNP affected countries (Belgium, France, Germany and the Netherlands) to identify herd management risk factors for BNP occurrence. Data were collected using structured face-to-face and telephone interviews of farm managers and their local veterinarians. In total, 363 case farms and 887 control farms were included in a matched multivariable conditional logistic regression analysis. Case-control status was strongly associated with the odds of herd level use of the vaccine PregSure r BVD (PregSure, Pfizer Animal Health) (matched adjusted odds ratio (OR) 107.2; 95% CI: 41.0-280.1). This was also the case for the practices of feeding calves colostrum from the calf's own dam (OR 2.0; 95% CI: 1.1-3.4) or feeding pooled colostrum (OR 4.1; 95% CI: 1.9-8.8). Given that the study had relatively high statistical power and represented a variety of cattle production and husbandry systems, it can be concluded with some confidence that no other herd level management factors are competent causes for a sufficient cause of BNP occurrence on herd level. It is suggested that genetic characteristics of the dams and BNP calves should be the focus of further investigations aimed at identifying the currently missing component causes that together with PregSure vaccination and colostrum feeding represent a sufficient cause for occurrence of BNP in calves.

The aim of this study was to assess the prevalence of production disease related indicators on 192 organic dairy farms in Germany, Spain, France and Sweden. The following indicators were used: raised somatic cell count (>100,000 cells/ml, subclinical mastitis), high fat/protein ratio (risk of ketosis), low milk fat (risk of acidosis), prolonged calving interval, clinical lameness, and mortalities of calves and cows. Prevalence of the assessed indicators varied widely between farms and countries. The median prevalence (interquartile range) were 51.3% (15.4) for subclinical mastitis, 10% (7.7) for risk of ketosis, 3.2% (4.7) for risk of acidosis, 42% (20.7) for prolonged calving interval, and 14.2% (20.4) for clinical lameness. The incidence risk of calves dying between 1 and 90 days of age was 0.002 (0.043) per month of risk. Cow mortality was 0.026 (0.048) per year at risk. The assessment has shown that a comprehensive set of indicators can be calculated from readily available data, sparing the need to establish new and costly procedures. Future research should focus on strategies for using the information most effectively to reduce the level of production diseases in organic dairy farms.

Les décisions de gestion de la santé animale correspondent à un large éventail de situations et de problèmes. Illustrant ce constat, sept maladies majeures des troupeaux bovins laitiers sont examinées pour identifier les facteurs les plus courants limitant l’efficacité des plans de maîtrise ainsi que les perspectives d’amélioration de la maîtrise sur le terrain. Pour les infections intra-mammaires, la recherche vise à la mise au point de vaccins multivalents, le ciblage des vaches à traiter par les antibactériens, la méthodologie des interventions en ferme, et l’augmentation de la résistance innée par la sélection génomique. Pour les strongyloses gastro-intestinales, les recherches prioritaires s’orientent aussi vers les stratégies de traitement anthelminthique raisonné et ciblé, la voie génétique semblant moins prioritaire que chez les petits ruminants. La maîtrise de la maladie de Mortellaro, affection de l’appareil locomoteur, ne pourra plus recourir aux désinfectants classiquement utilisés dans les pédiluves et des approches alternatives sont nécessaires. La maîtrise de la fièvre Q est à rechercher par la vaccination de l’ensemble du troupeau sur plusieurs années et l’hygiène de la parturition. La paratuberculose pourrait à terme être maîtrisée par la sélection génomique, en raison de l’absence de traitement et de vaccin efficaces et de l’existence de bases génétiques de résistance/résilience prometteuses. La maîtrise de l’infection par le virus BVDV semble pouvoir être atteinte par des mesures sanitaires combinées ou non avec la vaccination. La quasi-éradication des sérotypes exotiques du virus de la fièvre catarrhale ovine pourrait être obtenue par la surveillance ciblée et la vaccination massive et rapide. Les spécificités de l’étiologie, de l’épidémiologie et des moyens de maîtrise des maladies étudiées n’autorisent guère de conclusions génériques, Decisions in animal health management depend on a large variety of situations and problems. To illustrate this, seven major diseases of dairy herds were analysed to identify the main limiting factors for the effectiveness of the current control schemes and the perspectives toward better control in the field. Regarding intramammary infections, research directions focus on the development of multivalent vaccines, tools to better select cows to be treated with antibiotics, on-farm intervention methodology and the enhancement of animal resistance via a contribution of genome-wide selection techniques. For gastro-intestinal strongyloses, priority was also given to rational and selective anthelmintic treatments, genetic improvement of innate resistance seeming less a priority than for small ruminants. The control of Mortellaro disease, a locomotor disorder, should receive attention to develop alternatives because of the forecasted ban of the principal disinfectants used for footbaths. Q fever control can be reached by prolonged vaccination of the whole herd and adequate management of parturition hygiene. Johne disease is probably a good candidate disease for genomic selection, especially given the absence of treatment and very effective vaccine and the presence of a quite promising background of resistance/resilience. Infection by BVDV seems to be controllable by only sanitary measures, associated or not with a vaccination scheme. Eradication of exotic serotypes of BTV can be reached by targeted surveillance and quick and massive vaccination. Specificities in etiology, epidemiology and control techniques of the diseases under study do not quite allow drawing generic conclusions.

Beef cow-calf farming systems are assumed to be resilient to biological disturbances that induce variations in herd demography; however, this hypothesis has not been fully investigated to date. Modeling is an interesting approach to study farming system resilience and to evaluate the impact of biological disturbances, taking into account interactions between system components, including biological variability and management practices. Our objective was to evaluate the resilience of beef cow-calf farming systems to variations in fertility and mortality using a modeling approach. We studied the direct effect of variations in demographic parameters on production objectives without explicitly representing the causes of the variations. We developed a stochastic model to represent the population dynamics of a beef cow-calf herd with breeding by natural service and biological processes occurring at the animal level. The model was validated by comparing observed and simulated distributions of the calving-to-calving interval, which were found to be consistent. Resistance was evaluated by the proportion of simulations where the objective in terms of number of weaned calves is reached even when there is a disturbance that persists for 10 yr. Reversibility was evaluated by the time needed to return to the predisturbance production level. Beef cow-calf farming systems did not appear to be resistant to variations in mortality and infertility rates except when increases in the infertility rates were low (0.02 for cows and 0.03 for heifers). Critical situations, consequently, may emerge with regard to farm production if management practices are not adapted. Reversibility was observed for disturbances that persist for up to 5 yr. However, the system needed 2 to 3 yr to recover its predisturbance production level and up to 4 yr after an increase in cow infertility of 0.12.

Veterinarians could be the expected sparring partners of organic dairy farmers in promoting animal health which is one of the main organic principles. However, in the past organic dairy farmers did not always consider veterinarians to be pertinent advisors for them. The objectives of this study are – from private veterinary practitioners’ point of views- i) to describe the roles of veterinarians today in organic dairy farmers’ animal health promotion strategies, ii) to identify factors related to organic farming which determine their role on organic dairy farms, and, iii) to identify opportunities for improvement of veterinarians’ advisory services for organic dairy herds. Fourteen veterinarians, providing herd health advisory services to dairy farmers, were interviewed using qualitative semi-structured research interviews. A modified approach to Grounded Theory was used for data collection and analysis. Most often veterinarians had only contact with the organic dairy farmers in cases of individual ill animals or acute herd health problems. Even though certain veterinarians experienced situations and approaches of animal health and welfare on organic dairy farms not meeting their standards, they were not always able to establish themselves an advisory role supporting farmers in improving this. Indeed, organic production principles, regulations and farmers’ health approaches challenged veterinarians’ values on animal health and welfare and their perceptions of ‘good veterinary practices’. Also, some veterinarians considered that there was no direct economic interest for them in the organic dairy sector and that could diminish their willingness to invest in this sector. Possible opportunities for improvement were identified; for example proposing more proactively advice via existing organisations, by making adaptations to advisory services for the organic sector and/or by dissociating veterinarians’ curative role from their advisory role in disease prevention.

Production diseases have an important negative effect on the health and welfare of dairy cows. Although organic animal production systems aim for high animal health levels, compliance with European organic farming regulations does not guarantee that this is achieved. Herd health and production management (HHPM) programs aim at optimizing herd health by preventing disease and production problems, but as yet they have not been consistently implemented by farmers. We hypothesize that one reason is the mismatch between what scientists propose as indicators for herd health monitoring and what farmers would like to use. Herd health monitoring is a key element in HHPM programs as it permits a regular assessment of the functioning of the different components of the production process. Planned observations or measurements of these components are indispensable for this monitoring. In this study, a participatory approach was used to create an environment in which farmers could adapt the indicators proposed by scientists for monitoring the five main production diseases on dairy cattle farms. The adaptations of the indicators were characterized and the farmers' explanations for the changes made were described. The study was conducted in France and Sweden, which differ in terms of their national organic regulations and existing advisory services. In both countries, twenty certified organic dairy farmers and their animal health management advisors participated in the study. All of the farmers adapted the initial monitoring plan proposed by scientists to specific production and animal health situation on their farm. This resulted in forty unique and farm-specific combinations of indicators for herd health monitoring. All but three farmers intended to monitor five health topics simultaneously using the constructed indicators. The qualitative analysis of the explanations given by farmers for their choices enabled an understanding of farmers' reasons for selecting and adapting indicators. This is valuable information for scientists involved in the design of HHPM programs. Advisors in the field also can benefit from this participatory approach because it transforms monitoring tools provided by scientists into farm-specific tools.

A recent study evaluating whether reproductive data could be used for syndromic surveillance found an increased frequency of early calving (calving occurring a few days earlier than expected) in areas exposed to the Bluetongue virus serotype 8 (BTV-8) in northern Europe. A high proportion of herds infected during the 2006–2009 European outbreak were not reported through the surveillance system. The objectives of this study were (1) to quantify the increase in the frequency of early calving associated with the exposure to BTV-8 in late gestation and (2) to determine whether this association could be found in populations exposed to BTV-8 but without reported clinical signs. Increases in frequency of early calving were quantified for cows in herds located in the 2007 outbreak area in France, reported or not as cases. Increases were detected for cows in both categories of herds with a larger effect in herds reported after clinical signs. Moreover, the largest effect was found for exposures occurring during the latest stage of pregnancy, suggesting that BTV infection could trigger calving in cows in late gestation, a few days earlier than expected. This is the first study quantifying the association between a viral infection and a shortened pregnancy length (still within a normal range). The high magnitude of the increase in frequency of early calving, their occurrence in herds from infected areas but not reported, and the short time interval between exposure and the occurrence of the event confirm the interest of using early calving as an indicator for syndromic surveillance. Electronic supplementary material The online version of this article (doi:10.1186/s13567-015-0296-7) contains supplementary material, which is available to authorized users.

Many believe the health status of organic dairy herds in Europe should be improved to meet consumers’ and legislators’ expectations to improve animal welfare. This paper reports on a study in four countries that examined dairy farmers’ intentions towards improving the health status of their organic herds through the use of the Theory of Planned Behaviour. It was found that farmers across the countries were positive about taking additional preventative measures to improve the health status of their herds. They believed this would not only improve herd physical performance, such as milk yield and fertility, but also achieve greater cost effectiveness and improved job satisfaction for them. Most study farmers would implement a tailored package of improvement measures designed by the study team with higher uptake most likely being by younger farmers, those who make greater use of veterinarians and professional advisory services, and those supplying specialist milk-marketing chains. Furthermore, farmers will be most likely to take-up additional health promotion if compatible with their everyday activities and if they have strong business performance goals aimed at maximising the physical performance of the herd.

International audience; This study aimed to evaluate the use of routinely collected reproductive and milk production data for the early detection of emerging vector-borne diseases in cattle in the Netherlands and the Flanders region of Belgium (i.e., the northern part of Belgium). Prospective space-time cluster analyses on residuals from a model on milk production were carried out to detect clusters of reduced milk yield. A CUSUM algorithm was used to detect temporal aberrations in model residuals of reproductive performance models on two indicators of gestation length. The Bluetongue serotype-8 (BTV-8) epidemics of 2006 and 2007 and the Schmallenberg virus (SBV) epidemic of 2011 were used as case studies to evaluate the sensitivity and timeliness of these methods. The methods investigated in this study did not result in a more timely detection of BTV-8 and SBV in the Netherlands and BTV-8 in Belgium given the surveillance systems in place when these viruses emerged. This could be due to (i) the large geographical units used in the analyses (country, region and province level), and (ii) the high level of sensitivity of the surveillance systems in place when these viruses emerged. Nevertheless, it might be worthwhile to use a syndromic surveillance system based on non-specific animal health data in real-time alongside regular surveillance, to increase the sense of urgency and to provide valuable quantitative information for decision makers in the initial phase of an emerging disease outbreak.

The detrimental effect of bluetongue virus serotype 8 (BTV-8) on fertility was quantified in seroconverting cows. Although the effect on individual cows provides information regarding the potential biological burden of infection, losses at a herd level are also dependent on the proportion of infected cows within the herd. The objectives of this study were to quantify the average effect of BTV-8 exposure in field conditions on the fertility of dairy cows in previously naïve herds, and to determine the at-risk period of decreased fertility related to the date of detection of the disease in the herd. The effect of BTV-8 exposure on fertility was assessed using the 90-d-return-to-service rates after the first artificial insemination (AI) calculated for cows in exposed herds (during the 2007 epizootic in France) and compared with that for cows in unexposed herds. Only herds with a confirmed detection that were reported after clinical suspicion were included. To determine the at-risk period of decreased fertility, variations of fertility in exposed herds were quantified according to the time interval between the date of AI for individual cows and the date that disease was detected in the herd. Survival analyses were used to assess the risk of decreased fertility associated with BTV-8 exposure, adjusting for the main factors known to influence fertility. The episode at risk for decreased fertility depended on the month of disease detection in the herd. For herds detected early in the epizootic, fertility was decreased for cows inseminated from 1 mo before to 1 mo after the date of disease detection in the herd. Depending on time interval between the date of AI of cows and the date of detection in the herd, the increase of return-to-service rate associated with BTV-8 exposure varied from 8 to 21 percentage points of 90-d return to service. The episode of decreased fertility is likely due to a combination of the effect of the infection at different stages of conception and early pregnancy and the delayed exposure of cows due to the spreading of the virus within herds. For herds detected during the second half of the epizootic, fertility was decreased for cows inseminated more than 2 mo before detection, which suggests a delay in the detection of clinical signs following virus introduction in the herd. No correlation was observed between the effect of BTV-8 exposure on fertility and the incidence of BTV-8 in the local geographical area. Given the duration of the period that cows were at risk for decreased fertility and the magnitude of the effect, the average BTV-8 exposure in naïve herds led to major losses.

International audience; In Europe, on-farm biosecurity measures, involving a strict all-in/all-out batch-management system and decontamination of the rearing rooms between consecutive batches, are recommended to control Salmonella infection in growing pigs. However, im- plementation of these measures is often relaxed under common farming conditions. Therefore, this study was conducted to assess the relative contributions of batch- management system and room decontamination efficacy on Salmonella seroprevalence for different growing rates and subsequent slaughter ages of pigs. Because the impact of these factors cannot be easily evaluated by an observational approach in commercial farms, a stochastic simulation model representing the population dynamics, herd management, and Salmonella infection within a farrow-to-finish pig herd was used. Realistic levels were set for each factor under study (3 for batch-management system and slaughter age; 4 for room decontamination) to generate 54 simulation scenarios. Salmonella shedding prevalence in groups of slaughter pigs was then compared. A sensitivity analysis was performed to rank the impacts of the 3 factors on output. Batch-management system had little effect. In contrast, room decontamination efficacy had the greatest impact on Salmonella prevalence in pigs at slaughter. A drop in decontamination efficacy from 100 to 50%, with a strict all-in/all-out batch-management system and for all slaughter ages tested, noticeably increased (P < 0.001) the prevalence and almost doubled it for the reference slaughter age. Our results suggest that the control of Salmonella in pig herds should primarily focus on room decontamination efficacy. Provided that a good level of room decontamination is en- sured, some flexibility in batch management, in term of pig mixing, would be acceptable to limit the number of underweight pigs delivered to the slaughterhouse.

International audience; Enteric and respiratory diseases are the most frequent health disorders of calves. They are associated with mortality or lower growth rate and induce treatment costs. Enteric and respiratory pathogens can be transmitted via contacts between calves, which depend on calf housing systems and management. This study aimed at describing the main calf housing systems across Europe and at assessing the consequences of such housing facilities in terms of risk for calf infectious diseases. This was done through the use of a questionnaire distributed to experts in epidemiology and cattle farming systems in each European country. A literature review was performed on the risk factors associated with calf infectious diseases transmission and targeted in the questionnaire. Answers from 14 countries were obtained. A wide range of housing systems were described. However, four main systems could be identified and ranked in ascending order of risk for neonatal diarrhoea and respiratory infectious diseases: individual pen until weaning, individual pen for 4 weeks, individual pen for 2 weeks, and collective pen from the separation of the calf with its dam. Although the housing systems are known to play a role in disease transmission, they are currently not fully described in literature concerning risk factors for calf infectious diseases. In a given farm, the risk assessment for calf infectious diseases should consider classical risk factors such as hygiene, feeding practices and air conditioning, on top of a precise description of the housing system.

The effects of infection by Mycobacterium avium paratuberculosis (Map) on dairy cows are poorly documented and quite controversial. This retrospective study aimed at quantifying the variation in non-return to service of Holstein dairy cows according to their Map-infection status. Three different statuses were defined based on both individual and herd tests results: ELISA positive cow, all tests negative cow in a negative herd and all tests negative cow in a positive herd. Whatever the age at Map testing, the status was attributed to a cow from its first lactation onwards. Non-return to service was determined at 200 days after first and second services. The study was performed from 1999 to 2007 on 185,950 AI from 48,914 cows in early stage of the infection in 1069 herds by logistic regression controlling for known factors influencing non-return rate. Non-return rate was higher for infected cows compared to negative cows from negative herds (RR of 1.10 or +3.9 points of % of non-return rate). The effect was significant for parities 1 and 2 (RR of 1.11 and 1.12, respectively) but not for higher ones. This effect was lower when comparing positive cows to negative cows in the same herds but relative risks were still above 1. The hypothesis that the effect of Map on non-return depends upon the stage of infection is formulated.

Models have been developed to represent the spread of bovine viral diarrhoea virus (BVDV) in cattle herds. Whereas the herd dynamics is well known, biological data are missing to estimate the parameters of the infection process. Our objective was to identify the parameters of the infection process that highly influence the spread of BVDV in a dairy herd. A stochastic compartmental model in discrete time represented BVDV infection in a typical Holstein dairy herd structured into five groups (calves, young versus older heifers, lactating versus dry cows). Model sensitivity was analysed for variations in the probability of birth of persistently infected ( P ) calves ( b P ), mortality of P animals ( m P ), within- and between-group transmission rates for P and transiently infected ( T ) animals (respectively, β w P , β b P , β w T , β b T ). Three to five values were tested per parameter. All possible combinations of parameter values were explored, representing 3840 scenarios with 200 runs for each. Outputs were: virus persistence 1 year after introduction, time needed to reach a probability of 80% for the herd to be virus-free, epidemic size, mean numbers of immune dams carrying a P foetus, of P and of T animals in infected herds. When considered together, m P and β b P accounted for 40–80% of variance of all outputs; b P and β w T accounted each for less than 20% of variance; β b T and β w P accounted for almost no percent of variance of the outputs. Parameters β w T and b P needed to be more precisely estimated. The influence of m P indicated the effectiveness of culling P calves, the influence of β b P indicated the role of the herd structure in BVDV spread, whereas the influence of b P indicated the possible role of vaccination programs in controlling within-herd BVDV spread.

Today, disease surveillance protocols fail to improve herd health due to a lack of compliance of farmers. An explanatory factor could be that farmers and scientists who design these protocols do not use the same indicators for health surveillance. The aim of this research was to describe how various health indicators differ between farmers and scientists when designing a herd health surveillance tool. Twenty semi-structured research interviews were conducted with French organic dairy farmers and their advisors in animal health. The indicators adopted for herd health surveillance and their characteristics are described and analysed to identify how large the gap is between the indicators used by farmers and those proposed by scientists. Each farmer chose a unique combination of herd health indicators and alert levels. Not one farmer adopted all the indicators as proposed by the scientists. Alternative indicators proposed by farmers and those proposed by farmers can be close to those proposed by scientists or far away, respectively by choosing indicator for earlier detection of disease or indicators measuring very farm specific health management measures for example. Furthermore, analysis of the transcribed interviews allowed identifying a variety of reasons that explain the choice of alternative indicators proposed by farmers. Thus, the results show a great heterogeneity amongst farmers in indicators used for herd health surveillance. Moreover, a gap was identified between what scientists consider as indicators for herd health surveillance and what is adopted in the field. The description of the characteristics of the alternative indicators proposed by farmers and the understanding of some of the reasons for their choices could be used in the design of better herd health surveillance protocols that are more acceptable in field conditions

Enzootic bovine leukosis is a disease of cattle caused by bovine leukemia virus (BLV). The virus causes a persistent, life‐long infection in a subset of B cells. Malignant tumours (lymphomas) ultimately develop in 2–5% of infected animals, predominantly in adult cattle older than 3–5 years. Lymphomas invariably lead to death of the animal within months. Before 1960, BLV was endemic in dairy herds in Northern/Eastern Europe and North America. Since then it has spread to all continents. The disease has been successfully controlled and eliminated from many countries in Europe. There is no evidence to suggest that any significant reservoir of BLV exists among other species, nor for any role of BLV in human disease or cancers. BLV exhibits a slow, progressive spread within a herd and it is likely to persist if control measures are not applied. The main modes of transmission are perinatal from cow to calf, via colostrum and milk, and close contact that allows transfer of infected lymphocytes, such as dehorning and injections using non‐sterile utensils. Transfer between herds is almost entirely by movement of infected animals. Suitable methods have been developed for diagnosis of BLV infection in specimens of blood, milk and lymphomas. EBL has a negative impact on milk yield and leads to increased premature culling. The welfare consequences of lymphomas vary according to the location and magnitude of organ involvement. Criteria for maintaining country freedom from EBL differ substantially between OIE and EU. Surveillance for freedom should be based on a combination of serological testing of adult animals and identification of lymphomas at slaughter.

An assessment of a report issued by the European Commission in 2002 is presented about the oral vaccination of foxes against rabies, as well as additional topics such as the rabies aetiology and its occurrence in Europe, the target species for oral vaccination, i.e. foxes and raccoon dogs, the oral vaccines available and their thermostability, rabies surveillance and monitoring, and the recent international guidelines for rabies surveillance are discussed. Foxes are the only known reservoir for rabies in Europe, and raccoon dogs are important transmitters, while other carnivores play a less important epidemiological role. The demographic expansion of raccoon dogs and their movements after hibernation are risk factors for rabies recurrence. The combined densities of foxes and raccoon dogs, which often share the same habitats, could allow rabies epizootics to persist. The epidemiological role and the pathogenesis of rabies in raccoon dogs and other carnivores must still be clarified. Four vaccines are authorised in the EU and their effectiveness is proven to successfully contribute to rabies elimination. Experimental and field evidence shows that climatic and weather conditions may impact on bait casings and vaccine stability. Data on the stability of vaccine baits under different field conditions should be provided. It is recommended that bait should keep its integrity at the release point. Because of bait stability issues, the season most appropriate for implementing oral rabies vaccination or a heat‐stable vaccine should be considered. Rabies surveillance and monitoring of vaccination, based on assessment of bait uptake and seroconversion in host species, are important tools for the evaluation and adjustment of vaccination campaigns, although alternatives to tetracyclines as biomarkers should be developed. Oral immunisation by vaccine baits has proven to be successful in eliminating terrestrial wildlife rabies, but long‐term strategy, temporal continuity of vaccination and cross‐border cooperation are needed and recommended.