Multi-Criteria Decision Analysis in Food Safety Risk Management: The Case of Dioxins in Baltic Fish.

The Swedish risk management case of Baltic fatty fishes, in which dioxin levels may be too high, is a typical multidimensional food safety decision problem involving public health, economic, environmental and socio-cultural aspects. To effectively address the dioxin food safety problem, the multiple dimensions and conflicting interests of stakeholders have to be considered systematically when evaluating competing risk management options. The objectives of this study were to illustrate the applicability of the Multi-Criteria Decision Analysis (MCDA) method for multidimensional food safety risk management problems, and to evaluate the Swedish dioxin risk management using MCDA. The results show that the MCDA method is indeed a relevant tool for modelling the multifactorial Swedish dioxin problem and for initiating discussions amongst stakeholders to increase the acceptance of chosen strategies. Abolishing the derogation from the European Commission's maximum limits for the presence of dioxins in Swedish fish is the dominant strategy for risk assessors, whereas the preferences provided by the other stakeholders would suggest a continuation of the derogation without providing consumer information. However, the preferences of female consumers match with the 2011 decision of the Swedish government to ask for a derogation in combination with consumer information. The conclusion drawn from our MCDA analysis is comparable to the government's decision that-given the gradual reduction in dioxin concentrations in Baltic fish-the decision to continue providing consumer information or not mainly depends on how risk managers balance the preferences of the different stakeholders.

Interactions between risk assessors and risk managers during three major food incidents in Europe.

Risk analysis consists of risk assessment (RA), risk management (RM), and risk communication (RC). In most countries, RA and RM of food safety are separated to achieve a high scientific integrity, and typically occur in sequential order. However, in case of a food safety incident, even though being separate processes, RA and RM are performed simultaneously due to great time pressure and expected high impacts. The aim of this study was to analyze and evaluate the observed interactions between RA and RM processes, during three major food incidents in Europe, and to provide suggestions for possible improvement. Based on the differences observed between the three cases, strengths and weaknesses of each system have been identified. The enterohemorrhagic Escherichia coli (EHEC) crisis in 2011 in Germany, the horsemeat scandal in 2013 in Ireland, and the fipronil incident in 2017 in the Netherlands were used as case studies. Timelines of these incidents and crisis management procedures in place in each of the three countries provided the basis for further analysis. First, results showed that details of the communication processes between RA and RM bodies were frequently lacking in crisis management protocols. Second, RA, RM, and RC processes differed for each incident, due to differences in estimated risk for public health, but also due to differences in the organization within a country. Based on our results, we recommend that crisis management protocols should contain a section on communication between RA, RM, and on communication between member states in the EU.

Reproductive hormone use and its association with herd-level factors on Dutch dairy farms.

We studied the use of the 3 commonly used reproductive hormones, namely prostaglandins, GnRH, and progesterone, and associated herd-level factors on 760 Dutch dairy farms from 5 veterinary clinics. From 2017 to 2019 we collected data on the sales of reproductive hormones, converted this data into the number of reproductive hormone doses conducted, and expressed this as the annual number of reproductive hormone doses per 100 adult dairy cows. Additional herd-level information was available for 2019. Due to the excess of zeros in the data set (i.e., a substantial number of farms did not use any hormones), we used a zero-inflated negative binomial model to identify related herd-level factors for the use of reproductive hormones. In the entire study period of 2017 to 2019, 5.8% of the dairy farms did not use any reproductive hormones, with the proportion of nonusers varying between 0.0 and 10.3% per veterinary clinic. This proportion was around 13.5% on an annual basis. Prostaglandins were the most frequently used reproductive hormone in Dutch dairy cows (62.9%), followed by GnRH (33.1%) and progesterone (4.0%). Furthermore, participating in a veterinary herd health management program had a significant effect on reproductive hormone use. These farms used more reproductive hormones than farms that did not participate in a herd health management program and were less represented in the group of nonuser farms. Technologies, such as pedometers and automatic milking systems, also had an effect on reproductive hormone use. The presence of pedometers or activity monitors did not reduce the use of the reproductive hormones but was associated with a greater frequency of users. Farms with an automatic milking system used more reproductive hormones than farms with a conventional milking system. With this study, we have made a first step in achieving transparency in the Dutch dairy industry by providing an objective overview of reproductive hormone use on Dutch dairy farms and identifying associations with some herd-level factors.

Effects of flow-controlled vacuum on milking performance and teat condition in a rotary milking parlor.

The objective of this study was to compare a vacuum control system that increases milking system vacuum during the peak flow period of milking to conventional constant vacuum control technology regarding its effect on milk flowrate and milking duration. Further objectives were to study the effects of flow-controlled vacuum on milking parlor performance. An observational study was conducted on a commercial dairy farm milking from 848 to 896 cows per day over the study period using a 60-stall rotary milking parlor. The flow-controlled vacuum control system was applied for 3 wk. Milking performance and teat condition were compared with 3-wk periods prior and subsequent to the test period using conventional vacuum control. Statistical analysis was performed assuming a cross-sectional study design during each period. Flow-controlled vacuum increased peak milk flowrate by 12% and increased average milk flowrate by 4%. The decrease in individual cow milking duration was proportional to milk yield per milking. Postmilking teat condition was good during the entire study period. The occurrence of rough teat ends was slightly reduced during the flow-controlled vacuum period with no meaningful difference in the occurrence of teats with blue color, palpable rings, or petechia. The combination of reduced vacuum during the low flow period of milking and the decrease in milking duration are likely factors that are protective of teat tissues. Bioeconomic modeling of the use of flow-controlled vacuum on the performance of rotary milking parlors, using the data that were collected during the study, showed that the reduction in milking duration of individual cows allows a higher rotary parlor speed. Modeled parlor throughput increased by 5.0% to 419 cows/h, 6.8% to 407 cows/h, and 4.2% to 326 cows/h when 80%, 95%, and 99% of the cows were finished milking at the end of the rotation for a 60-stall parlor. Model results showed that increased parlor throughput resulted in increased labor efficiency, reduced labor costs for milking, and a positive benefit-cost ratio on the investment for all but the smallest herd and parlor sizes considered.

Quarter- and cow-level risk factors for intramammary infection with coagulase-negative staphylococci species in Swiss dairy cows.

Bacteriological status, evaluation of udder symmetry, udder hygiene, and teat end scores of 92 dairy cows were assessed on 3 Swiss dairy farms in a longitudinal 1-yr study to determine risk factors for intramammary infection (IMI) with coagulase-negative staphylococci (CNS) species. Farm visits were performed monthly including sterile quarter milk sampling and udder evaluation of all lactating cows. Milk samples were evaluated for the presence of staphylococci using selective agar plates. Species identification was performed using MALDI-TOF mass spectrometry. Intramammary infection was defined as milk samples having ≥100 cfu per mL of milk according to culture results. Overall, 3,151 quarter samples were included in the statistical analysis. Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus xylosus, and a Staphylococcus warneri-like species were the 4 most prevalent CNS species found. Hierarchical multivariable logistic regression models were built to evaluate risk factors for species-specific CNS IMI. Risk factors for Staph. chromogenes IMI were presence in herd B, the period from June 2014 to August 2014 and December 2014 to February 2015, and presence of udder edema. For Staph. haemolyticus, the relevant risk factor included coinfection with Staph. xylosus coinfection with other than the above-mentioned CNS species ("others") and the period from June 2014 to November 2014. Coinfection with Staph. haemolyticus and "others," the periods from June 2014 to August 2014 and December 2014 to February 2015, early phase of lactation (1-60 d in milk), and belonging to herd B were significantly associated with Staph. xylosus IMI. Mid and late lactation, coinfection with Staph. xylosus, and the period September 2014 to May 2015 were identified as significant risk factors for Staph. warneri-like IMI. For Staph. chromogenes, 60.6 and 26% of the variance was observed at the quarter and cow level, respectively, whereas for the other investigated species the highest variance was observed at the sample level. The predominant species within herds differed and was most pronounced for the Staph. warneri-like species.

A multiarm randomized field trial evaluating strategies for udder health improvement in Swiss dairy herds.

The aims of this study were to quantify the effectiveness of specialist advice about udder health in Swiss dairy herds and to compare 3 different udder health improvement strategies against a negative control group. In 2010, 100 Swiss dairy herds with a high (between 200,000 and 300,000 cells/mL) yield-corrected bulk milk somatic cell count (YCBMSCC) were recruited for a 1-yr multiarm randomized field trial. The herds were visited between September and December 2011 to evaluate udder health-management practices and then randomly allocated into 1 of 4 study arms containing 25 herds each. The negative control study arm received neither recommendations for improving udder health nor any active support. The remaining 75 farmers received a herd-specific report with recommendations to improve udder health management. The positive control study arm received no further active support during 2012. The veterinarian study arm received additional support in the form of monthly visits by their herd veterinarian. Finally, the study group study arm received support in the form of bimonthly study group meetings where different topics concerning udder health were discussed. One year later, implementation of recommendations and changes in udder health were assessed. Of the recommendations given, 44.3% were completely implemented, 23.1% partially, and 32.6% were not implemented. No differences in implementation of recommendations were noted between the 3 study arms. At study enrollment, farmers were asked for the study arm of their preference but were subsequently randomly assigned to 1 of the 4 study arms. Farmers that were assigned to the study arm of their preference implemented more recommendations than farmers assigned to a study arm not of their preference. No decrease in the within-herd prevalence of cows that had a high (≥200,000 cells/mL) composite somatic cell count was observed in herds that had a YCBMSCC ≥200,000 cells/mL at the start of intervention. However, the 3 study arms with intervention (positive control, the veterinarian, and the study groups) prevented an increase in the within-herd prevalence of cows that had a high somatic cell count in herds with a low YCBMSCC at the start of the intervention compared with the negative control study arm. In the year after sending the report, herds assigned to the study group study arm had a reduced incidence rate of treated mastitis cases in comparison with the year before sending the report.

[Cost-benefit analysis of an intervention to improve udder health in Swiss dairy farms]. / Kosten-Nutzen-Analyse einer Intervention zur Verbesserung der Eutergesundheit in Schweizer Milchviehbetrieben.

The objective of this study was to calculate the national costs associated with udder health in Switzerland and to estimate the cost effectiveness of an udder health intervention program. In 49 farms, yearly mastitis associated costs before and during an intervention were collected at herd level. Costs were calculated for each lactating cow being present in the herd. At the beginning of the intervention, 24 farms received a report with recommendations to improve the udder health. In the following year, those herds were followed-up by their veterinarian at a monthly basis. The other 25 farms were used as a negative control group and neither received any recommendations nor any follow-up. In the first year of analysis (2010), the median udder health associated costs were 209.- Swiss Francs for each lactating cow, regardless of the intervention group. During the intervention period (2012), mastitis associated costs were 191.- Swiss Francs for control farms and 396.- Swiss Francs for farms with veterinary intervention on a monthly basis. The median additional costs for herds with intervention were 159.- Swiss Francs per lactating cow. At the national level, mastitis associated costs were estimated at 129.4 millions of Swiss Francs per year. The cost effectiveness of future mastitis control programs can be evaluated with the help of the deterministic model developed during this study.

Le but du présent travail était de calculer les coûts de la santé de la mamelle dans des exploitations laitières suisses et d'estimer l'efficacité économique d'une intervention en vue de l'améliorer. Pour cela on a relevé les coûts liés aux mammites sur une année dans 49 exploitations, et cela durant l'année précédant l'intervention puis dans l'année de l'intervention et on l'a divisé par le nombre de vaches en lactation. Vingt-quatre exploitations ont reçu au début de l'étude des recommandations en vue d'améliorer la santé de la mamelle et ont ensuite été suivies mensuellement durant une année par leur vétérinaire d'exploitation. Les 25 autres exploitations n'ont reçu aucune recommandation et ont été utilisées comme groupe de contrôle. Dans la première année d'analyse (2 ans avant l'intervention, 2010), les coûts moyens de la santé de la mamelle, indépendamment du groupe s'élevaient à CHF 209.­ par vache en lactation. Durant l'année de l'intervention, ils se montaient à CHF 191.­ pour les exploitations de contrôle contre CHF 396.- pour les exploitations suivies. Les dépenses supplémentaires durant l'intervention s'élevaient en moyenne à CHF 159.­ par vache en lactation. Au niveau national, on estime les coûts liés aux mammites à CHF 129.4 millions. Les modèles de calcul utilisés dans la présente étude permettent de juger à l'avenir de la rentabilité des programmes de contrôle des mammites.

Associations between the decrease in bovine clinical mastitis and changes in dairy farmers' attitude, knowledge, and behavior in the Netherlands.

The aim of this study was to associate changes in dairy farmers' self-reported attitude, knowledge, and behavior with the decrease in incidence rate of clinical mastitis (IRCM). Farmer-diagnosed clinical mastitis cases were obtained from two surveys conducted before (July 2004-June 2005) and at the end (2009) of a mastitis control program in the Netherlands. Information on farmers' attitude, knowledge, and behavior was also obtained by sending the farmers the same questionnaire during both surveys. Multivariable linear regression models identified that the herd level 2004 IRCM explained 28% of the variation in the decrease of IRCM. Changes in farmers' attitude and knowledge, and changes in farmers' behavior additionally explained 24% and 5%, respectively. These results suggest that the way management measures are executed may be at least as important as the fact that they are executed. No control group was available for this study because the intervention was applied at the national level. We therefore do not claim any causal relationships.

Genotype-specific risk factors for Staphylococcus aureus in Swiss dairy herds with an elevated yield-corrected herd somatic cell count.

Bovine mastitis is a frequent problem in Swiss dairy herds. One of the main pathogens causing significant economic loss is Staphylococcus aureus. Various Staph. aureus genotypes with different biological properties have been described. Genotype B (GTB) of Staph. aureus was identified as the most contagious and one of the most prevalent strains in Switzerland. The aim of this study was to identify risk factors associated with the herd-level presence of Staph. aureus GTB and Staph. aureus non-GTB in Swiss dairy herds with an elevated yield-corrected herd somatic cell count (YCHSCC). One hundred dairy herds with a mean YCHSCC between 200,000 and 300,000cells/mL in 2010 were recruited and each farm was visited once during milking. A standardized protocol investigating demography, mastitis management, cow husbandry, milking system, and milking routine was completed during the visit. A bulk tank milk (BTM) sample was analyzed by real-time PCR for the presence of Staph. aureus GTB to classify the herds into 2 groups: Staph. aureus GTB-positive and Staph. aureus GTB-negative. Moreover, quarter milk samples were aseptically collected for bacteriological culture from cows with a somatic cell count ≥150,000cells/mL on the last test-day before the visit. The culture results allowed us to allocate the Staph. aureus GTB-negative farms to Staph. aureus non-GTB and Staph. aureus-free groups. Multivariable multinomial logistic regression models were built to identify risk factors associated with the herd-level presence of Staph. aureus GTB and Staph. aureus non-GTB. The prevalence of Staph. aureus GTB herds was 16% (n=16), whereas that of Staph. aureus non-GTB herds was 38% (n=38). Herds that sent lactating cows to seasonal communal pastures had significantly higher odds of being infected with Staph. aureus GTB (odds ratio: 10.2, 95% CI: 1.9-56.6), compared with herds without communal pasturing. Herds that purchased heifers had significantly higher odds of being infected with Staph. aureus GTB (rather than Staph. aureus non-GTB) compared with herds without purchase of heifers. Furthermore, herds that did not use udder ointment as supportive therapy for acute mastitis had significantly higher odds of being infected with Staph. aureus GTB (odds ratio: 8.5, 95% CI: 1.6-58.4) or Staph. aureus non-GTB (odds ratio: 6.1, 95% CI: 1.3-27.8) than herds that used udder ointment occasionally or regularly. Herds in which the milker performed unrelated activities during milking had significantly higher odds of being infected with Staph. aureus GTB (rather than Staph. aureus non-GTB) compared with herds in which the milker did not perform unrelated activities at milking. Awareness of 4 potential risk factors identified in this study guides implementation of intervention strategies to improve udder health in both Staph. aureus GTB and Staph. aureus non-GTB herds.

A longitudinal study investigating the prevalence of Staphylococcus aureus genotype B in seasonally communal dairy herds.

Staphylococcus aureus is a major mastitis-causing pathogen. Various genotypes have been recently identified in Switzerland but Staph. aureus genotype B (GTB) was the only genotype associated with high within-herd prevalence. The risk of introducing this Staph. aureus genotype into a herd may be increased by frequent animal movements. This may also be the case when cows from different herds of origin are commingled and share their milking equipment for a limited period of time. The aim of the present study was to determine the prevalence of Staph. aureus GTB in seasonally communal dairy herds before and after a summer period when dairy farming is characterized by mixing cows from different herds of origin in 1 communal operation. In addition, the environment was investigated to identify potential Staph. aureus GTB reservoirs relevant for transmission of the disease. A total of 829 cows from 110 herds of origin in 9 communal operations were included in the study. Composite milk samples were collected from all cows during the first or second milking after arrival at the communal operation and again shortly before the end of the season. Swab samples from the environment, involved personnel, and herding dogs present were collected before the cows arrived. At the end of the season, sampling of personnel was repeated. All samples were analyzed for the presence of Staph. aureus GTB using an established quantitative PCR. At the beginning of the season, Staph. aureus GTB-positive cows were identified in 7 out of 9 communal operations and the within-communal operation prevalence ranged from 2.2 to 38.9%. At the second sampling, all communal operations were Staph. aureus GTB positive, showing within-communal operation prevalence from 1 to 72.1%. The between-herd of origin prevalence increased from 27.3 to 56.6% and the cow-level prevalence increased from 11.2% at the beginning of the season to 29.6% at the end of the season. On 3 different communal operations, Staph. aureus GTB-positive swabs from seasonally employed personnel were identified at the end of the season. The results indicate that Staph. aureus GTB can easily spread in communal operations when cows from different herds of origin are mixed during the summer season. Effective management measures need to be designed to prevent the spread of Staph. aureus GTB in seasonally communal herds.

[Mastitis management in Swiss dairy farms with udder health problems]. / Mastitis-Management in Schweizer Milchviehbetrieben mit Eutergesundheitsproblemen.

The objective of this study was to describe the udder health management in Swiss dairy herds with udder health problems. One hundred dairy herds with a yield-corrected somatic cell count of 200'000 to 300'000 cells/ml during 2010 were selected. Data concerning farm structure, housing system, milking technique, milking procedures, dry-cow and mastitis management were collected during farm visits between September and December 2011. In addition, quarter milk samples were collected for bacteriological culturing from cows with a composite somatic cell count ≥ 150'000 cells/ml. The highest quarter level prevalence was 12.3 % for C. bovis. Eighty-two percent of the pipeline milking machines in tie-stalls and 88 % of the milking parlours fulfilled the criteria for the vacuum drop, and only 74 % of the pipeline milking machines met the criteria of the 10-l-water test. Eighty-five percent of the farms changed their milk liners too late. The correct order of teat preparation before cluster attachment was carried out by 37 % of the farmers only. With these results, Swiss dairy farmers and herd health veterinarians can be directed to common mistakes in mastitis management. The data will be used for future information campaigns to improve udder health in Swiss dairy farms.

Le but de cette étude était de décrire la gestion de la santé de la mamelle dans des exploitations connaissant des problèmes en la matière. Pour cela, on a sélectionné 100 exploitations laitières présentant, en 2010, un nombre théorique de cellules dans le lait de mélange compris entre 200'000 et 300'000 cellules/ml. Les données relatives à la structure de l'exploitation, à la détention des animaux, à la technique et au travail de traite ainsi qu' à la gestion du tarissement et des mammites ont été relevées lors d'une visite d'exploitation dans la période allant de septembre à décembre 2011.En outre des échantillons de lait des vaches avec un nombre de cellules ≥ 150'000/ml ont été analysés bactériologiquement. La prévalence la plus élevée au niveau des quartiers était celle de C. bovis avec 12.3 %. Lors du test des machines à traire relatif à la chute du vacuum, 82 % des installations des stabulations entravées et 88 % des salles de traites étaient dans la zone normale et seules 74 % des installations réussissaient le «test des 10 l d'eau¼. Le changement des manchons était effectué trop tard dans 85 % des exploitations. Seul 37 % des exploitants se tenaient, lors de la préparation des mamelles, à un ordre correct des phases de travail. Ces résultats doivent rendre les producteurs de lait et les vétérinaires d'exploitations attentifs aux erreur de gestion les plus fréquentes. Ces données serviront de bases pour les campagnes d'information futures, dans le but d'améliorer la santé de la mamelle dans les exploitations laitières suisses.

Improving bovine udder health: a national mastitis control program in the Netherlands.

Because of increasing bulk milk somatic cell counts and continuous clinical mastitis problems in a substantial number of herds, a national mastitis control program was started in 2005 to improve udder health in the Netherlands. The program started with founding the Dutch Udder Health Centre (UGCN), which had the task to coordinate the program. The program consisted of 2 parts: a research part and a knowledge-transfer part, which were integrated as much as possible. The knowledge-transfer part comprised 2 communication strategies: a central and a peripheral approach. The central approach was based on educating farmers using comprehensive science-based and rational argumentation about mastitis prevention and included on-farm study group meetings. Comprehensive education materials were developed for farmers that were internally motivated to improve udder health. In the peripheral approach it was tried to motivate farmers to implement certain management measures using nontechnical arguments. Mass media campaigns were used that focused on one single aspect of mastitis prevention. These communication strategies, as well as an integrated approach between various stakeholders and different scientific disciplines were used to reach as many farmers as possible. It should be noted that, because this intervention took place at a national level, no control group was available, as it would be impossible to isolate farmers from all forms of communication for 5 years. Based on several studies executed during and after the program, however, the results suggest that udder health seemed to have improved on a national level during the course of the program from 2005 to 2010. Within a cohort of dairy herds monitored during the program, the prevalence of subclinical mastitis did not change significantly (23.0 in 2004 vs. 22.2 in 2009). The incidence rate of clinical mastitis, however, decreased significantly, from 33.5 to 28.1 quarter cases per 100 cow years at risk. The most important elements of the farmers' mindset toward mastitis control also changed favorably. The simulated costs of mastitis per farm were reduced compared with a situation in which the mastitis would not have changed, with € 400 per year. When this amount is extrapolated to all Dutch farms, the sector as a whole reduced the total costs of mastitis by € 8 million per year. It is difficult to assign the improved udder health completely to the efforts of the program due to the lack of a control group. Nevertheless, investing € 8 million by the Dutch dairy industry in a 5-yr national mastitis control program likely improved udder health and seemed to pay for itself financially.

Relationship between somatic cell count status and subsequent clinical mastitis in Dutch dairy cows.

High composite somatic cell counts (CSCC) in dairy cows may develop into clinical mastitis (CM), suggesting that prevention or intervention of high CSCC may prevent CM later in lactation. The objective of this study was to quantify the relationship between high CSCC in dairy cows and the first subsequent case of CM in the same lactation. Farmer-diagnosed cases of CM and test day CSCC measurements during 1 year of 13,917 cows in 196 randomly selected Dutch dairy herds were available for analysis. Cows were followed in 1 lactation from the first test day postpartum until CM, drying off, culling or end of study. Cox proportional hazards models with time-varying CSCC levels were used to estimate the effect of high CSCC (≥200,000cells/ml) on the time until the first case of CM. A shared frailty effect was included to adjust for clustering of cows within herds. The proportion of cows developing CM after a CSCC measurement was 11%. Primiparae with a high CSCC had a 4-fold higher hazard for subsequent CM than primiparae with a low CSCC; multiparae with a high CSCC had a 2-fold higher hazard than multiparae with a low CSCC. Additionally, multiparae with a low CSCC had a 2-fold higher hazard for CM occurrence than primiparae with a low CSCC. Increasing the threshold for high CSCC showed that the risk for CM increased. If the last CSCC before CM was low, CSCC information of 2 preceding test days was more predictive than CSCC information from only the last test day. When the last CSCC was high, CSCC information of 2 preceding test days did not have added predictive value. This study identified that approximately 25% of first subsequent CM cases after a CSCC measurement can potentially be prevented when cows are prevented to get high CSCC or when high CSCC cows are removed from the population. This corresponded with a decrease in the proportion of lactating cows with CM after a CSCC measurement from 11% to 7%.

What veterinarians need to know about communication to optimise their role as advisors on udder health in dairy herds.

The veterinary practitioner is one of the most important advisors for farmers in the field of udder health. He or she has the tools to improve udder health if farmers are motivated to do so. Many farmers think that udder health is important, but this does not always mean that management of mastitis is up to standard. Many veterinarians are of the opinion that they are unable to convince their clients of the possible profits to be gained from investing in management of mastitis. Something is required to bridge this gap. This article, based on data and experiences from The Netherlands, describes the communication issues that can be considered in order to improve the role of the veterinarian as advisor, to achieve better udder health. The outcome is beneficial for both farmers and veterinarians, the former for reasons of economics, welfare and ease of work; the latter because it creates extra, challenging work. It is concluded that the veterinary practitioner is in an ideal situation to advise and motivate farmers to improve udder health but, to do this, the means of communication need to take account of the different learning styles of farmers. The most important aspects of such communication are found to be a pro-active approach, personalisation of messages, providing a realistic frame of reference for the farmer, and use of the farmer's social environment. Importantly, all persons and organisations in a farmer's social environment should articulate the same message.

Bioeconomic modeling of lactational antimicrobial treatment of new bovine subclinical intramammary infections caused by contagious pathogens.

This study determined the direct and indirect epidemiologic and economic effects of lactational treatment of new bovine subclinical intramammary infections (IMI) caused by contagious pathogens using an existing bioeconomic model. The dynamic and stochastic model simulated the dynamics of Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli during lactation and the dry period in a 100-cow dairy herd during 1 quota year. Input parameters on cure were obtained from recent Dutch field data. The costs of clinical IMI, subclinical IMI, and intervention were calculated into the combined total annual net costs of IMI per herd. The cost effectiveness of 4 scenarios with lactational intervention was determined; scenarios included no intervention, treatment after 1 mo of infection, treatment after 2 mo of infection, and treatment after 1 mo of infection and culling of uncured cows after 2 mo of infection. Model behavior was observed for variation in parameter input values. Compared with no lactational intervention, lactational intervention of new subclinical IMI resulted in fewer clinical flare ups, less transmission within the herd, and much lower combined total annual net costs of IMI in dairy herds. Antimicrobial treatment of IMI after 1 mo of infection and culling of uncured cows after 2 mo of infection resulted in the lowest costs, whereas treatment after 2 mo of infection was associated with the highest costs between the scenarios with intervention. Changing the probability of cure resulted in a nonlinear change in the cumulative incidence of IMI cases and associated costs. Lactational treatment was able to prevent IMI epidemics in dairy herds at high transmission rates of Strep. uberis, Strep. dysgalactiae, and E. coli. Lactational treatment did not limit the spread of Staph. aureus at high transmission rates, although the associated costs were lower compared with no intervention. To improve udder health in a dairy herd, lactational treatment of contagious subclinical IMI must therefore be preceded by management measures that lower the transmission rate. Lactational treatment of environmental subclinical IMI seemed less cost effective. Detection of subclinical IMI needs improvement to be able to most effectively treat subclinical IMI caused by contagious pathogens during lactation.

Variation in herd level mastitis indicators between primi- and multiparae in Dutch dairy herds.

Composite somatic cell count data from the national test day recording and reported cases of farmer diagnosed clinical mastitis were used to estimate the occurrence of mastitis from July 2004 to June 2005 in primi- and multiparae in the Netherlands. Herds had to participate in the test day recording and had to have at least 50 cows. A random selection of 396 of these dairy herds provided composite somatic cell count data, while 205 dairy herds additionally reported on clinical mastitis cases. Prevalence of subclinical mastitis was calculated per herd as the proportion of cows with somatic cell count>200,000cells/ml. The incidence rate to clinical mastitis was calculated as the number of clinical mastitis cases divided by the number of cow days at risk per herd. Negative binomial models were used to correct for overdispersion. Mean herd level subclinical mastitis prevalence was 12.8% (95% CI: 12.2-13.5%) in primi- and 27.1% (95% CI: 26.2-28.1%) in multiparae. Mean herd level clinical mastitis cases were observed 20.2 (95% CI: 18.3-22.4) and 39.6 (95% CI: 37.1-42.3) times per 100 cow-years at risk, respectively. Some herds had a high mastitis occurrence in one parity group, while it was low in the other. Parity-specific monitoring is needed to identify such herds.

Host adaptation of bovine Staphylococcus aureus seems associated with bacteriological cure after lactational antimicrobial treatment.

Staphylococcus aureus causes a wide range of diseases in multiple species. Some sequence types (ST) are observed in a variety of hosts, whereas other strains are mainly associated with bovine mastitis, suggesting host adaptation. We propose that host adaptation of Staph. aureus may influence bacteriological cure of bovine subclinical mastitis after antimicrobial treatment. To test this hypothesis, multilocus sequence typing was performed on Staph. aureus isolates from 60 treated and 79 untreated control quarters that were obtained from well-defined cohorts of dairy cows from a recently conducted randomized field trial on early treatment of subclinical mastitis. Bovine-associated ST were distinguished from non-bovine-associated ST based on the literature and public databases. The association between host adaptation and bacteriological cure was investigated using population-averaged logistic regression models. Thirteen ST were identified, with approximately 80% of isolates belonging to bovine-associated ST. The odds for cure were around 2.5 times as high for non-bovine-associated ST as for bovine ST in treated quarters, whereas no difference in spontaneous cure was observed in untreated control quarters. In addition, host adaptation was related to known predictors of cure, such as penicillin susceptibility and somatic cell count. All isolates belonging to non-bovine-associated ST were resistant to penicillin, whereas the majority of isolates belonging to bovine-associated ST were penicillin susceptible. Penicillin-resistant bovine-associated strains were associated with high somatic cell counts compared with other strains. The correlation between penicillin resistance, cell counts, and host adaptation may affect the association between host adaptation and cure. For diagnostic purposes, a simple and fast alternative to multilocus sequence typing of Staph. aureus to determine host adaptation may be valuable.

Therapeutic effects of antimicrobial treatment during lactation of recently acquired bovine subclinical mastitis: two linked randomized field trials.

Two linked randomized field trials were performed on 39 herds in the Netherlands to 1) determine therapeutic effects of antimicrobial treatment of recently acquired subclinical mastitis (RASCM) during lactation, 2) evaluate the effect of duration of subclinical mastitis on therapeutic outcome, and 3) identify factors related to the therapeutic success of RASCM. Cows with a first elevated composite somatic cell count (CSCC) after 2 consecutive low CSCC measurements were eligible for enrollment in trial 1 (treatment at the first elevated CSCC). Quarter milk samples were collected to determine bacteriological status for major pathogens and coagulase-negative staphylococci. Cows with one or more culture-positive quarters with a quarter somatic cell count (QSCC) >or=100,000 cells/mL were defined to have RASCM and were randomly assigned treatment or control (no treatment). Untreated cows from trial 1 that had a second elevated CSCC at the next milk recording were eligible for enrollment in trial 2 (treatment at the second elevated CSCC). In trial 2, staphylococci-positive cows (Staphylococcus aureus and coagulase-negative staphylococci) were randomly assigned to treatment or control. Farmers used their own treatment protocols to treat quarters in both trials. Bacteriological cure was defined as absence of the pathogen identified pre-intervention in 2 samples post-intervention; QSCC, CSCC, and milk yield were also analyzed. Hierarchical logistic and linear models were used to determine therapeutic effects and to identify factors related to therapy outcome. Treated quarters had a higher bacteriological cure rate than control quarters for all pathogens in both trials. Treatment resulted in lower QSCC and CSCC, whereas milk yield was not affected by treatment. Bacteriological cure of RASCM was better in quarters with a low QSCC pre-intervention and in coagulase-negative staphylococci-positive quarters. Control quarters with a single culture-positive sample pre-intervention also had a higher bacteriological cure than control quarters with >or=2 culture-positive samples. Time of antimicrobial treatment affected bacteriological cure for penicillin-sensitive Staph. aureus. Bacteriological cure tended to be higher for Staph. aureus after treatment at the first elevated CSCC compared with treatment at the second elevated CSCC. Thus, early treatment of Staph. aureus might be more effective than later treatment.

Explaining mastitis incidence in Dutch dairy farming: the influence of farmers' attitudes and behaviour.

When mastitis incidence increases, either infection pressure has increased or cows' resistance has decreased. This usually indicates that farm management is not optimal. Numerous quantitative studies have demonstrated the effect of management practices on mastitis. In most of these studies, the identified risk factors could explain only part of the variance in mastitis incidence on farms. Several studies suggest that the unexplained variance is caused by farmers' attitudes towards different aspects of mastitis treatment and preventive behaviour. This study aims to determine, to quantify and to specify the extent to which farmers' attitudes, over and above farmers' behaviour, are factors that explain the variation in mastitis incidence, measured in terms of the quantifiable effect of management factors. An extensive survey on self-reported attitudes, behaviour and mastitis incidence was conducted on 336 Dutch dairy farms. Results of multiple linear regression analyses show that farmers' self-reported behaviour and attitudes together explain 48%, 31% and 23% of the variation within, respectively, the average farm bulk milk somatic cell count (BMSCC), the clinical mastitis incidence and the combined clinical and subclinical mastitis incidence. Both behaviour and attitudes explain part of the variance. However, most of the variance in all three dependant measures is explained solely by the attitude variables. The variation in BMSCC value is best explained by (1) farmers' normative frame of reference about mastitis, (2) farmers' perceptions about the control of mastitis and (3) the perceived effect of a BMSCC penalty level. The variation in clinical mastitis is best explained by farmers' perceptions about mastitis control. The variation in the combined clinical and subclinical mastitis incidence rate is best explained by the perceived effect of a BMSCC penalty level and the frequency of contact with others. The results of this study show that farmers' attitudes are a better measure than farmers' self-reported behaviour to explain and predict differences in mastitis incidence between farms. Consequently, future research and animal health promotion programs should take into account not only farmers' behaviour, but also farmers' attitudes. This study provides a first empirical investigation into the social processes applicable to mastitis incidence and is therefore considered a good starting point for future research to further investigate the causal effect of attitude change on farmers' behaviour and animal health.

Intra-class correlation attributable to claw trimmers scoring common hind-claw disorders in Dutch dairy herds.

Data of a cross-sectional study on prevalence of seven common bovine-claw disorders were used to calculate the intra-class correlation coefficients (ICCs) for claw trimmers. Fifteen professional claw trimmers were trained in diagnosing claw disorders uniformly. During regular trimming of all dairy cows in a herd, they recorded the presence (yes/no) of hind-claw disorders for digital dermatitis (DD), chronic laminitis (CL), sole ulcer (SU), white-line disease (WLD) and interdigital hyperplasia (HYP). For the claw disorders interdigital dermatitis/heel-horn erosion (IDHE) and sole haemorrhage (SH), claw trimmers also recorded (using graduated scores 1-3) the extent of the lesion. Complete information of 21,153 animals from 361 herds in The Netherlands was recorded between July 2002 and December 2003. To assure objective recording of claw disorders, ideally there would not be any correlation between observations. However, quantified ICCs from claw-trimmers observations ranged from 4.9% for DD to 38.0% for CL, while ICCs for herd ranged from 7.9% for SU to 26.7% for DD. Changes in the cut-off values for the diagnosis of IDHE and SH did not result in any relevant changes of the ICCs from claw-trimmers observations and these remained larger than the ICC explained by the herd. Based on these results, we conclude that for estimating measures of frequencies for different claw disorders, uniformity in recording certain diagnoses becomes an issue to consider when involving more than one observer.