Government veterinarians' perceptions of routine biosecurity focused on dairy cattle farms in north-western and north-eastern Spain.

The implementation of biosecurity measures in livestock production systems can be affected by the psychosocial factors of its stakeholders, which can be observed through their knowledge, attitudes and perceptions/practices. In Spain, there are no regulations per se to promote biosecurity. Of all stakeholders, farmers and veterinarians have been addressed in previous biosecurity studies, but not veterinarians belonging specifically to the government services. This study explores this particular group's perceptions of routine biosecurity in livestock production systems in north-western and north-eastern Spain, an understanding of which could help to improve the implementation of biosecurity measures on farms. Eleven interviews were conducted with veterinarians from different levels of the government services in Galicia and Catalonia, and were analyzed through content analysis. Dairy cattle farms were considered as the reference livestock production systems. The respondents stress the limited availability of staff and time resources for biosecurity. The advisory role of government veterinarians is not well recognized among farmers, who feel that their services prioritize their sanctioning role. In fact, government veterinarians consider that farmers only implement biosecurity measures to avoid being sanctioned, and not because they are aware of the importance of biosecurity. Meanwhile, the participants comment that biosecurity regulations should be flexible and need to consider the contexts of the farms where biosecurity measures are implemented. Finally, government veterinarians are willing to attend biosecurity meetings together with all farm stakeholders, at which the government services could be informed about biosecurity issues on farms. The person who could take on the biosecurity advisory role should be defined, along with further discussion of such matters as the responsibilities of each stakeholder. Government veterinary services need to be considered in studies of biosecurity operations in order to improve their implementation. It is therefore concluded that government veterinarians are seeking to balance their own institutional perspective with that of farmers and veterinarians in the routine implementation of biosecurity measures.

Factors Associated with the Introduction of Mycobacterium avium spp. Paratuberculosis (MAP) into Dairy Herds in Galicia (North-West Spain): The Perception of Experts.

This study aimed at quantifying expert opinions on the risk factors involved in Mycobacterium avium subsp. paratuberculosis (MAP) infection in dairy cattle herds. For this purpose, potential risk factors associated with the introduction of MAP into dairies were chosen based on a literature review and discussions with researchers and veterinarians. For each factor, a decision tree was developed, and key questions were included in each. Answers to these key questions led to different events within each decision tree. An expert opinion workshop was organized (following the recommendations of the OIE), and ordinal values ranging from 0 to 9 (i.e., a null to very high likelihood of infection) were assigned to each event. The potential risk factors were also incorporated into a structured questionnaire that was responded to by 93 farms where the sanitary status against MAP was known. Thereby, based on the values given by the experts and the information collected in the questionnaires, each farm was assigned a score based on their MAP entry risk. From these scores (contrast variable) and using a ROC curve, the cut-off that best discriminated MAP-positive and -negative farms was estimated. The most important risk factors for the introduction of MAP, according to expert opinions, involved purchase and grazing practices related to animals under six months of age. The scores obtained for each farm, also based on the expert opinions, allowed MAP positive/MAP negative farms to be discriminated with 68.8% sensitivity and 68.7% specificity. These data should be useful for focusing future training initiatives and improving risk-reduction strategies in the dairy industry.

Influence on the implementation of biosecurity measures in dairy cattle farms: Communication between veterinarians and dairy farmers.

This study was carried out in two regions in Spain (Catalonia and Galicia) through eight focus groups; four for dairy farmers and four for veterinarians. The results showed that dairy farmers and veterinarians attributed responsibility to one another for not following biosecurity practices. The study brings to light contradictions among veterinarians and certain individual veterinary practices that participated in the study, which lead to doubt and confusion on the part of dairy farmers. Distinct perceptions were also identified of the role that government authorities should play in relation both to training and sanctions as a means of improving biosecurity on dairy farms. Additionally, the participants expressed varying opinions as to whether biosecurity measures ought to be made mandatory or remain voluntary. Results from this study highlight the need to promote initiatives through which distinct stakeholders such as veterinarians, government authorities, and dairy farmers can develop consensus-based messages on the implementation of biosecurity practices.

Dairy farmers' decision-making to implement biosecurity measures: A study of psychosocial factors.

Biosecurity measures are a set of management procedures that prevent the risk of introducing and spreading infectious diseases to a farm, although these measures are rarely implemented in dairy farms. There are some studies that have identified that the decision to implement biosecurity measures can be influenced by several psychosocial factors (attitudes and behaviours). Thus, the objective of this study was to examine the psychosocial factors (and their interactions) influencing the implementation of biosecurity measures in dairy farms in Spain, through the views of dairy farmers and veterinarians from Catalonia (northeast Spain) and Galicia (northwest Spain). Face-to-face in-depth interviews were performed with 16 dairy farmers (nine from Catalonia and seven from Galicia) and 16 veterinarians (eight from Catalonia and eight from Galicia). Grounded theory analysis was performed on the transcripts, following the subtopics of: information sources, individual factors of the farmer, social dynamics, official veterinary services and other factors. The study identified the importance of veterinarians as a source of information, including their communication skills, the individual experiences of farmers, traditions of the farms and availability of time and space in the dairy farmer's decisions making. Further, it suggests the need to deepen the knowledge of the farm workers and the obligatory biosecurity measures. This research represents a starting point to develop future strategies to improve the implementation of biosecurity measures in dairy farms.

A survey of biosecurity measures and serological status for bovine viral diarrhoea virus and bovine herpesvirus 1 on dairy cattle farms in north-west and north-east Spain.

BACKGROUND: Biosecurity is a key measure to reduce and prevent the introduction of diseases to farms and minimise spread of diseases within a herd. The aim of the study was to characterise the current application of biosecurity measures on dairy cattle farms in Spain along with their bovine viral diarrhoea and infectious bovine rhinotracheitis status. METHODS: Data on biosecurity measures for 124 dairy herds were collected using a questionnaire. The sanitary status of these farms for bovine viral diarrhoea and infectious bovine rhinotracheitis was also assessed using antibody ELISA. Data were analysed using multiple correspondence analysis and a two-step cluster analysis. RESULTS: Three main clusters of farms were identified: clusters 1 and 2 included herds of small and intermediate sizes. These, particularly cluster 1, showed the most deficiencies in the control of vehicles and visitors. However, laboratory tests were always performed on purchased animals. Cluster 3 had the largest herd sizes, with somewhat better biosecurity control of vehicles and visitors. However, farms in this cluster also purchased the most animals, sometimes without testing, and hired external workers more often. CONCLUSION: The study indicated that, in the study population, there are serious shortcomings in the application of biosecurity measures on dairy farms, exposing them to disease transmission. This survey also highlights regional and herd size-related differences in the implementation of biosecurity. Collecting data is an important first step to identification of specific weaknesses in different farm typologies, and an adequate follow-up is needed to ensure that measures are implemented correctly on farms.

Evaluation of four commercial serum ELISAs for detection of Mycobacterium avium subsp. paratuberculosis infection in dairy cows.

During the first 3 months of 2006, a study was performed on four dairy cattle herds with a history of clinical paratuberculosis, to evaluate different enzyme-linked immunosorbent assays (ELISAs). Serum samples obtained from 326 animals were analysed using four ELISAs to detect antibodies to Mycobacterium avium subsp. paratuberculosis (MAP). Kappa (kappa) concordance coefficients in pairwise comparisons of the ELISA outcomes ranged up to 0.22 (linear kappa) and 0.25 (quadratic kappa). When the borderline positives obtained were considered as negatives, kappa values remained low (kappa up to 0.19). Having performed the serological tests, faecal samples were then obtained from 55 animals (including all animals testing positive in two or more ELISAs) from the same herds. Faecal culture and faecal polymerase chain reaction (PCR) for the detection of MAP were negative in all cases. The results indicate that neither the currently available serum ELISAs nor faecal culture and PCR are effective for the early detection of MAP in dairy cattle.

Prevalence of serum antibodies to Mycobacterium avium subsp. paratuberculosis in cattle in Galicia (northwest Spain).

Prior to establishing a control and prevention program for Johne's disease in cattle in Galicia (northwest Spain), a survey was conducted to estimate the prevalence of the disease. For this survey, 61,069 animals of at least 1-year of age from 2735 randomly selected herds were bled and samples analyzed with a commercial ELISA. The estimated true individual-level prevalences--assuming the manufacturer's reported test sensitivity of 48.5% and specificity of 98.9%--were 3.02% in dairy cattle, 1.03% in beef cattle and 2.83% in animals from farms with both dairy and beef cattle. True herd prevalences (with herds declared positive if one or more animals tested positive) were 10.69% for dairy herds, 0% for beef herds and 2.71% for mixed herds. When herds were declared positive if at least two animals tested positive, true herd prevalences were 14.75% for dairy herds, 1.47% for beef herds and 12.01% for mixed herds. Assuming a higher specificity of 99.4%, true individual-level prevalences increased to 4.03% in dairy herds, 2.07% in beef herds and 3.84% in mixed herds. Herd prevalences were 27.77%/18.79%, 2.78%/2.40% and 5.70%/12.24% (using the one/two-animal cut-offs) in dairy, beef and mixed herds, respectively. In conclusion, these results seem to indicate that a small percentage of cows and a rather high percentage of dairy herds in this region are MAP-seropositive.

Associations between Mycobacterium paratuberculosis sero-status, milk quality parameters, and reproduction in dairy cows.

The objective of this study was to investigate the influence of Mycobocterium avium subsp. paratuberculosis (MAP) sero-status of dairy cows on different milk production variables and reproductive traits. The study was carried out on 40 herds from the region of Galicia (North-West Spain). These herds were randomly selected from a larger group that had taken part in a voluntary paratuberculosis control program since 2005, which involves regular serum sampling of every adult animal to run antibody-ELISA tests. Milk production and reproductive data were obtained from the "Dairy Herd Improvement Program (DHIP) of Galicia". All the gathered data were processed following a linear regression model. Results indicated that there was no significant effect of MAP sero-status on individual milk production variables. However, a significant difference was observed at the calving-to-first-insemination interval, with an average increase of 14 days in positive animals compared to negatives. It has to be taken into consideration that the paratuberculosis status was only defined by the serological status. Since para tb-infected animals may have antbodies or may not, para tb-positive animals can also be included in the sero-negative group of animals, which may bias the results.

Evaluation of long-term antibody responses to two inactivated bovine viral diarrhoea virus (BVDV) vaccines.

The aim of the present study was to determine the serological response of heifers after vaccination with two inactivated bovine viral diarrhoea virus (BVDV) vaccines by means of various ELISA tests. Three dairy farms were selected from the Galicia region of Spain. In each herd, a batch of heifers to be vaccinated for the first time was selected and followed for 15 months. Heifers from farm 1 (n=25) were vaccinated with Vaccine A, whereas heifers from farm 2 (n=16) were vaccinated with Vaccine B. Heifers from farm 3 (n=17), where no BVDV vaccines were used, acted as controls. Blood samples were analyzed periodically for BVDV antibodies, using five commercial ELISAs, based on BVDV p80 antigen or whole virus. At the end of the study, none of the animals vaccinated with Vaccine A seroconverted according to p80 antibody status, whereas up to 80% tested positive by ELISA against whole virus antigen. For the animals vaccinated with Vaccine B, 2/16 animals seroconverted according to p80 antibody ELISAs, whereas all had seroconverted according to the ELISA against whole virus antigen. In most cases, based on the use of ELISAs to detect specific antibodies against the p80 protein, at 15 months post-vaccination with inactivated BVDV vaccines the responses did not seem to interfere with detection of antibody to BVDV infection. However, the finding of a small proportion of vaccinated animals seropositive against BVDV p80 antigen suggests that antibodies that interfere with diagnosis of BVDV infection within the herd could exist, even when using p80 ELISAs.

Bovine viral diarrhea virus: correlation between herd seroprevalence and bulk tank milk antibody levels using 4 commercial immunoassays.

The aim of the present study was to establish a relationship between the results obtained using the enzyme-linked immunosorbent assay (ELISA) technique for antibodies in blood serum and milk at herd level. For this purpose, 325 samples of bulk tank milk were analyzed with 4 antibody ELISAs from dairy herds with a prevalence of seropositive animals; seroprevalence was also evaluated. Data were arranged to analyze the sensitivity of the bulk tank milk test to detect herds with high risk of active infection (>65% seroprevalence) and the specificity to detect those with very few (<5%) or no (0%) seropositive animals, respectively. The sensitivity values ranged from 0.92 to 0.70 and the specificity from 0.83 to 0.54 to detect free herds (0% seroprevalence) and from 0.88 to 0.77 to detect herds with <5% of seropositive animals. In a quantitative approach, Pearson correlation coefficients, reported as a measure of linear association between herd seroprevalence and transformed optical density values recorded in bulk tank milk, ranged from 0.71 to 0.86. According to these results, the 4 antibody ELISAs would be valid tests for carrying out a herd classification program using milk samples.

Presence of Listeria, Arcobacter, and Campylobacter spp. in dairy farms in Spain.

Bacteria from genera Listeria, Campylobacter and Arcobacter are potentially zoonotic pathogens for humans and they may be detected in dairy cattle farms. In this study the presence of these bacteria was considered in dairy cattle farms in Galicia (northwest of Spain). In the first part of the study, bulk tank milk samples were collected to determine the herd prevalences of Listeria spp. in 98 dairy farms. Additionally 83 silage samples and 97 faeces samples of lactating cows were collected. L. monocytogenes was detected in 6.1%, 9.3% and 6.0% of these samples, respectively. With regard to Campylobacter spp. and Arcobacter spp., 254 faecal samples were collected on 89 dairy farms. Campylobacter spp. was found with a herd prevalence of 36%. It was also confirmed in 20.5% of dairy cattle faecal samples. Arcobacter spp. was isolated in 68.5% of the farms and in 41.7% of faecal samples, with A. cryaerophilus being the most frequently identified species. The results related to the prevalence of the bacteria included in this study confirm their presence in high numbers in different types of biological samples from dairy farms, and suggest that more epidemiological studies regarding this bacteria need to be performed.

Effect of the bovine viral diarrhoea virus (BVDV) infection on dairy calf rearing.

The aim of this study was to compare the cumulative incidence of mortality, clinical diarrhoea and respiratory disease in calves, during their first six months of age, in herds with different bovine viral diarrhoea virus (BVDV) infection status. Calves' health indicators were tested by comparing proportions in 101 farms with dissimilar infection condition. The results indicate that there was a significant relationship between the BVDV status (actively infected herd or not) and the cumulative incidence of mortality and respiratory disorders.

Monitoring bovine viral diarrhea virus (BVDV) infection status in dairy herds / Monitoramento do estado de infecção pelo vírus da diarréia viral bovina (BVDV) em rebanhos bovinos leiteiros

This study was designed to assess the relationship between antibodies against bovine viral diarrhea virus (BVDV) determined in the bulk tank milk (BTM) and the within-herd seroprevalence. We also assessed the efficiency of measuring antibody levels in BTM samples to monitor BVDV infection status in a herd. In the 81 farms included in the study, BTM samples were obtained and blood samples withdrawn from all cattle older than one year. The infection status was then determined in serum and milk using a commercial blocking ELISA based on the detection of anti-p80 antibodies. Apart from these baseline serum and milk samples, another BTM sample was collected from each herd 9 months later, and a third BTM sample obtained 9 months after this. In these second and third milk samples, anti-BVDV antibodies were determined using the same ELISA kit. Statistical tests revealed good agreement between herd seroprevalences (% seropositive animals in the herd) and the antibody levels detected in the BTM samples. During the 18 months of follow-up, the farms with persistently infected cattle at the study outset (14.8% of the herds) showed a significant decrease in BTM antibody titers after virus clearance. Conversely, a significant increase in BTM antibody levels was observed in the herds infected with BVDV during the follow-up period. Our findings indicate that monitoring antibody levels in the BTM is a useful method of identifying changes in the BVDV infection status of a herd.(AU)

Os objetivos do presente estudo foram avaliar a relação entre os níveis de anticorpos frente ao vírus da diarréia viral bovina (BVDV) no tanque de leite e a prevalência de animais seropositivos em cada rebanho; e também avaliar a eficiência da medição dos níveis de anticorpos no tanque de leite como método de monitoramento do status de infecção frente ao BVDV. Nos rebanhos estudados, obtiveram-se amostras de soro de todos os animais com idade superior a um ano, assim como uma amostra de tanque coletivo de leite. As amostras de soro e leite foram analisados por um teste ELISA de bloqueio baseado na detecção de anticorpos anti-p80. Posteriormente coletaram-se mais duas amostras do tanque de leite em cada exploração com intervalos de nove meses entre as coletas. Estas amostras foram analisadas com o mesmo ELISA. A análise estatística mostrou uma boa relação entre a soroprevalência dos rebanhos e a percentagem de inibição na amostra de tanque de leite. No decorrer do procedimento, aquelas explorações que possuíam animais PI no início do estudo (que representavam 14.8% dos rebanhos estudados) mostraram um decréscimo estatísticamente significativo dos níveis de anticorpos após a eliminação dos animais persistentemente infectados. Ao contrário, as explorações que sofreram a introdução da infecção durante o estudo mostram um incremento significativo nos níveis de anticorpos no leite. Nossas conclusões indicam que a avaliação de níveis de anticorpos no tanque de leite é um método útil de identificar mudanças do estado sorológico da infecção BVDV de rebanhos leiteiros.(AU)