Food/farmed animals 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 Francisco J Villaamil,1 Ignacio Arnaiz,2 Alberto Allepuz,3 Miquel Molins,4 Mercedes Lazaro,5 Bibiana Benavides,6 Sebastián J Moya,7 Jordi Casal Fabrega,8,9 Eduardo Yus,10 Francisco J Dieguez ‍ ‍ 11 ►► Additional material is ABSTRACT estimated to be the most cost-­effective protec- published online only. To view Background Biosecurity is a key measure to reduce and tion against animal diseases.1–3 please visit the journal online prevent the introduction of diseases to farms and minimise (http://​dx.​doi.​org/​10.​1136/​ Within the context of animal production, spread of diseases within a herd. The aim of the study biosecurity is defined as management activi- vetreco-​2020-​000399). was to characterise the current application of biosecurity ties that reduce the opportunities for infec- To cite: Villaamil FJ, Arnaiz I, measures on dairy cattle farms in Spain along with their tious agents to gain access to, or spread Allepuz A, et al. A survey of bovine viral diarrhoea and infectious bovine rhinotracheitis status. within, a production unit.4 Thus, it has two biosecurity measures and serological status for bovine Methods Data on biosecurity measures for 124 dairy main components: external and internal bios- viral diarrhoea virus and herds were collected using a questionnaire. The sanitary ecurity. External biosecurity entails preven- bovine herpesvirus 1 on status of these farms for bovine viral diarrhoea and tive measures and risk reduction strategies dairy cattle farms in north-­ infectious bovine rhinotracheitis was also assessed designed to avoid the introduction of patho- west and north-­east Spain. using antibody ELISA. Data were analysed using multiple genic infections (hazards), whereas internal Veterinary Record Open correspondence analysis and a two-­step cluster analysis. 2020;7:e000399. doi:10.1136/ biosecurity entails measures to limit within-­ Results Three main clusters of farms were identified: farm transmission of infectious hazards vetreco-2020-000399 clusters 1 and 2 included herds of small and intermediate between animals.5 6 Received 12 February 2020 sizes. These, particularly cluster 1, showed the most deficiencies in the control of vehicles and visitors. The importance of biosecurity is high- Revised 13 July 2020 However, laboratory tests were always performed on lighted in the EU health strategy. From 2007 Accepted 14 July 2020 purchased animals. Cluster 3 had the largest herd sizes, onwards, the EU embraced a new motto as with somewhat better biosecurity control of vehicles and part of its Animal Health Strategy, ‘preven- visitors. However, farms in this cluster also purchased tion is better than cure’, implemented by the the most animals, sometimes without testing, and hired EC.7 In 2019, the Council of the European external workers more often. Union still emphasised the key role of bios- Conclusion The study indicated that, in the study ecurity, which should be seen not only as the population, there are serious shortcomings in the concrete management and physical measures application of biosecurity measures on dairy farms, exposing them to disease transmission. This survey also designed to reduce the risk of transmission highlights regional and herd size-­related differences in of animal diseases at the farm level, but also the implementation of biosecurity. Collecting data is an as a wider concept, as a strategic and holistic important first step to identification of specific weaknesses approach to managing relevant risks.8 in different farm typologies, and an adequate follow-­up The putative benefits of undertaking is needed to ensure that measures are implemented biosecurity for disease prevention and/or correctly on farms. control include improvements in production © British Veterinary Association 2020. Re-­use permitted under efficiency (hence greater profits), animal CC BY-­NC. No commercial welfare, immune responses to vaccines, and re-­use. Published by BMJ. INTRODUCTION job satisfaction for producers, herd health For numbered affiliations see Infectious agents that affect livestock may professionals and other agricultural workers.9 end of article. be transmitted by various routes such as In addition, in pig herds, a link between Correspondence to live infected animals, trucks and other vehi- biosecurity and antimicrobial treatment-­ Dr Francisco J Dieguez; ​ cles, people, aerosols, fomites, wildlife and related criteria has been demonstrated and franciscojavier.​dieguez@​usc.​es other animal vectors. Biosecurity has been quantified.10  Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 1 Open access Despite these benefits, implementation of biosecurity region, no official control programme is established. The on dairy cattle farms is often insufficient. Poor or inap- farm typology in this region could be considered repre- propriate knowledge transfer is often cited as a poten- sentative of the rest of Spain. tial cause of disease spread.11 The main limitations and One hundred and twenty-­ four dairy farms were strengths of the biosecurity measures applied in dairy selected, 93 from Galicia and 31 from Catalonia, as part cattle farms have been studied recently in several coun- of a larger national project on risk analysis for the intro- tries.11–16 In Spain, despite the economic importance duction of BVDV and BoHV-1 to dairy cattle herds. They of milk production in some regions, current biosecu- represented 1.3 per cent and 5.7 per cent of the dairy rity practices on dairy farms have been scarcely studied, farms from Galicia and Catalonia, respectively. For farm except for a recent survey assessing perceptions and prac- selection, the project was presented to the veterinarians tices applied by rural veterinarians.17 responsible for health management in the different dairy Moreover, bovine viral diarrhoea (BDV) and infectious cattle areas from both regions. During their routine farm bovine rhinotracheitis (IBR) have been often considered visits, veterinarians willing to take part explained the in previous biosecurity studies, as the implementation project to the farmers. Those interested in participating of their related biosecurity measures should be priori- volunteered to enrol in this study, which was not incen- tised in biosecurity programmes.14 17 The sanitary status tivised. Thereby, the selection of farms was not random, of dairy cattle farms with respect to these two endemic and the sample size corresponds to those farmers who diseases is highly variable among Spanish regions. In voluntarily joined the project (conditional on their veter- some, the situation is unknown and the approach to inarians’ willingness to participate). managing outbreaks depends mainly on the actions of individual veterinarians and farmers. In others, mainly in Biosecurity questionnaire the north-­west, voluntary programmes were established Biosecurity data were obtained using a questionnaire. some time ago and now involve a large proportion of the The questionnaire was designed based on a literature cattle population.18 review,9–13 and discussions with researchers and veter- BDV and IBR, caused by the bovine viral diarrhoea virus inarians at the Santiago de Compostela University and (BVDV) and the bovine herpesvirus 1 (BoHV-1), respec- Autonomous University of Barcelona, regional govern- tively, are highly contagious diseases of economic and ment veterinarians and cattle veterinarians of diverse trade importance for the livestock industry worldwide. subspecialties in both ACs (online supplementary file 1). Several European countries have implemented official The questionnaire (available in Spanish and English voluntary or compulsory programmes to eradicate both on request) consisted of closed questions and included diseases.19 20 four sections: (1) general farm information (eg, location, The aim of the present study was to assess and charac- herd size, vaccination programmes); (2) animal move- terise the current application of biosecurity measures on ments (eg, origin of the animals, frequency of introduc- dairy cattle farms in two autonomous communities (ACs) tions, test, quarantine facilities, external rearing farms, of Spain (first-­level administrative division): Galicia and cattle fairs or competitions, pasture) and neighbouring Catalonia. Considering that BVD and IBR are endemic in herds (ie, other ruminant farms in a 1-­km radius); (3) most countries with cattle production in the absence of movements and types of vehicles and equipment (for live control programmes and given that many key biosecurity and dead animal transport, manure, slurry and feeding measures for cattle herds relate to these diseases,14 17 the vehicles, machinery) and biosecurity-­ related measures present study analysed the sanitary status of farms in rela- (eg, vehicles may enter inside the farm perimeter, vehi- tion to BVD and IBR along with biosecurity data. cles may enter inside the farm perimeter with animals from other farms); and (4) visitors and staff (eg, external workers; frequency of visits by professionals such as veter- MATERIALS AND METHODS inarians and technicians, or non-­professionals such as Area description and herds surveyed neighbouring farmers, who come in contact with the The study was conducted in two ACs of Spain: Galicia animals; use of protective clothing). (north-­west) and Catalonia (north-­east). Galicia is the The questionnaire was first administered to five test main dairy cattle area of the country, 55 per cent of farms farms (three in Galicia and two in Catalonia, all of which and 38 per cent of milk production. The mean herd are not included in the main sample) to assess for clarity size per farm is 43 cows, lower than the national mean of the question items and whether respondents had of 59.3, and farms are still predominantly family owned suggestions for improvement. As a result of this survey, and managed. In Galicia, an official voluntary BoHV-1 minor modifications were made to the questions. and BVDV control programme has been in place since Finally, in the study farms, the questionnaire was 2004. This region is representative of the production completed by a researcher from Santiago de Compos- type prevailing in the north-­west and Cantabric area of tela University (Galicia) or from Autonomous Univer- the country. By contrast, farms in Catalonia have a mean sity of Barcelona (Catalonia) (authors of the present herd size of 144 cows, with 4 per cent of the farms nation- study) during farm visits, with the farmer and the veteri- ally yielding 11 per cent of milk production.21 In this narian responsible for managing the health of each farm 2 Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 Open access being present. The interview appointments were sched- Initially, the frequencies of the different BoHV-1 and uled according to participants’ convenience. Ensuring BVDV profiles and biosecurity measures were analysed. the presence of the veterinarian (who knows the usual A multiple correspondence analysis (MCA) was management and biosecurity practices of each farm) and performed26 to characterise the current application of scheduling the interview during the visit to the farm itself biosecurity measures in dairy cattle farms from two ACs sought to improve the accuracy of the data collected. in Spain. MCA aims to reduce a set of possibly correlated In addition, farmers were informed that questionnaires variables (including all the biosecurity variables and the were processed anonymously and that no individual farm sanitary status of the farms) to a smaller group of linearly data would be disclosed. uncorrelated dimensions. The number of dimensions Each farm was visited once between July 2017 and April was set to two, to facilitate two-­ dimensional graphical 2018. The approximate time needed to complete the representation. The position of the full set of categories questionnaire and the farm visit was 2.5 hours. for each investigated variable (category points) on the MCA graph is the basis for revealing relationships among Sanitary status variables: variable categories with a similar profile tend to The BVDV and BoHV-1 infection status of the farms was group together, whereas negatively correlated categories determined using antibody ELISA following the guide- are located on opposite sides of the graph. The origin of lines from the Animal Health and Production Laboratory the graph reflects the weighted mean of the categories of Galicia22 and taking into consideration the fact that for each variable considered in the study (centroid). As farms that applied vaccines used inactivated vaccines in a result, the distance from the origin to a category point case of BVDV and marker vaccines (live or inactivated) is the reflection of the variation from the mean pattern in case of BoHV-1. (the most frequent category for each variable). In addi- Samples for antibody ELISA were collected by the tion, a two-­step cluster analysis (TSCA)27 was performed. veterinarians responsible for each farm involved in the TSCA aims to classify a sample of subjects (farms) on project within three months since the completion of the the basis of a set of measured variables into a number questionnaire. Briefly, blood was collected from all cattle of different groups such that similar subjects are placed from nine months to 24 months. At the same time, a bulk in the same group. Thereby, clusters of farmers with tank milk (BTM) sample was collected from each farm. similar implemented biosecurity measures and BVDV In case these samples tested ELISA-­negative, blood was and BoHV-1 profiles were identified. The frequencies of also collected and analysed for antibodies from all cattle entry of animals, vehicles and visitors were categorised older than two years to determine free status. Samples in quartiles for MCA and TSCA but were included in the were stored at −70°C until analysis. final results’ tables as mean and median frequencies. For BVDV, antibodies to the p80 antigen were deter- mined using a commercial blocking ELISA (BVD p80 RESULTS Ab, IDEXX Laboratories, The Netherlands). In animals BVDV and BoHV-1 profiles of the 124 farms are summa- vaccinated with inactivated vaccines, the antibodies rised in table 1. The proportion of farms categorised as mainly react with structural proteins rather than the p80 recent or active infection for both BVDV and BoHV-1 was antigen (non-­structural).23 This allowed for differenti- 5.6 per cent (7 of 124). Thirty per cent of the farms used ation between animals exposed to wild-­type BVDV and inactivated vaccines against BVDV, whereas the remainder the vaccine virus since live vaccines were not used in the did not vaccinate; 27 per cent used marker vaccines for herds examined here. For BoHV-1, two different tests BoHV-1, whereas the remainder did not vaccinate. were used depending on whether vaccines were used on Table 2 describes the biosecurity measures related the herd (IDEXX IBR gE antibody, IDEXX Laboratories) to animal movements and possible contact with other or not (IDEXX IBR gB antibody, IDEXX Laboratories). All tests were run in accordance with the manufacturer’s instructions. Table 1 BVDV and BoHV-1 sanitary status of 124 farms in Using the results of ELISA tests, three different farm Spain profiles were established for each of the two viruses: Sanitary status n (%) (1) farms with recent or active infection (seropositivity in heifers from nine months to 24 months born on the BoHV-1 Recent/active infection 13 (10.7) farm); (2) farms with seropositive adult animals (posi- Seropositive animals (but rearing heifers 48 (39.3) tive BTM or negative BTM with at least one seropositive free) cow >24 months) but all rearing heifers (9–24 months) Free farm 63 (50.0) seronegative; or (3) free farms (BTM and all individual BVDV Recent/active infection 44 (36.1) animals tested seronegative).22 24 25 Seropositive animals (but rearing heifers 24 (19.7) free) Statistical analysis Free farm 56 (44.3) All statistical tests were performed with SPSS V.15.0. Study data is provided as online supplemental file 2. BoHV-1, bovine herpesvirus 1; BVDV, bovine viral diarrhoea virus. Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 3 Open access domestic ruminants. The mean of purchases was 5.2 Table 2 Biosecurity measures related to purchase of cattle, or possible contact with other ruminants, for 124 farms in animals per year in farms that purchased cattle (46 of Spain 124, 37.1 per cent). It is noteworthy that 11 of 46 (23.9 per cent) farms purchased animals without any testing, n (%) and 120 of 124 farms (98.6 per cent) lacked adequate Purchase of animals (heifers/cows) quarantine facilities. Animal movement to cattle fairs or  No 78 (62.9) competitions took place only in seven of 124 farms (5.7  Yes (sanitary status assessed at origin) 18 (14.5) per cent). Embryo transfer was only performed in six of  Yes (sanitary status assessed on arrival) 17 (13.7) 124 (4.8 per cent) farms. Access to pasture was reported  Yes (without testing) 11 (8.9) by 54 of 124 farms (43.6 per cent), and 51.8 per cent Mean (median; Q1–Q3*) frequency of heifers or cows 5.25 (3; 2–6) (28 of 54) reported the possibility of contact with other purchased per year, when applicable (46 farms) domestic ruminants at the pasture. Transport of purchased heifers/cows Vehicles visiting the farms represented an infection risk for most of the surveyed farms because nearly all vehicles  Cannot contact other ruminants during transport 39 (84.8) entered inside the perimeter of all farms (table 3). The  Can contact other ruminants 7 (15.2) most frequently entering vehicles were feeder wagons  Not applicable 78 (mean 7.1 times/week), followed by those collecting live Adequate quarantine facilities† animals (for slaughter or calves for feedlot) (mean 2.6  Yes 4 (3.2) times/month). Moreover, in 114 of 124 farms (92.6 per  No 120 (96.8) cent), vehicles in the latter two categories were permitted External rearing‡ to enter the farms carrying domestic ruminants from other farms.  No 112 (90.2) Control of visits and staff also showed room for improve-  Yes 12 (9.8) ment (table 4). Most farms (111 of 124) had no perimeter Sanitary plan in the external rearing farm§ fences (89.3 per cent), and visitors’ parking was usually  Yes 6 (50.0) (120 of 124) inside the farm perimeter (96.7 per cent).  No 6 (50.0) Farms also commonly (115 of 124) could receive visitors  Not applicable 112 who, without protective clothing, had contact with the Embryo transfer animals (92.6 per cent). The MCA with standardised data explained 38.9 per  No 118 (95.2) cent of the variance in biosecurity and sanitary status  Yes (sanitary status of donor cows known) 6 (4.8) among the 124 farms. The percentage of variance  Yes (sanitary status of donor cows unknown) 0 (0) explained by the first dimension was 24.7 per cent and Cattle farms within 1 km for the second dimension was 14.2 per cent.  No 16 (12.9) The main results of the MCA (joint plot of category  Yes 108 (87.1) points) are presented graphically in figure 1. Figure 2 Sheep/goat farms within 1 km represents the clustered farms and their location on the MCA chart. Three main clusters were formed that  No 81 (65.3) included 122 out of the 124 herds. Online supplemen-  Yes 43 (34.7) tary table S1 (within-­cluster percentages) shows how each Sheep/goats on the farm sanitary category or biosecurity variable is split within  No 113 (92.6) each cluster.  Yes 11 (7.4) Cluster 1 (n=62) comprised herds located mainly in the Participation in cattle fairs/competitions upper left quadrant of the MCA chart. All these herds were  No 117 (94.3) from Galicia, with low mean herd size (51 cows). They were most frequently BVDV-­free and BoHV-1-­free. These  Yes (no return) 1 (0.8) farms checked the sanitary status of purchased animals,  Yes (possible return) 6 (4.9) either at the farm of origin or on arrival. However, they Pasture did not have adequate quarantine facilities. This cluster  No 70 (56.4) was the one that most often used external rearing farms.  Yes, no contact with other ruminants 28 (22.6) Access to pasture was observed more frequently than in  Yes, possible contact with other ruminants 26 (21.0) the other clusters (including possible contact between the farm’s cattle and ruminants from other farms). In *Q1: 25th percentile; Q3: 75th percentile. †Separate buildings, outside farm perimeter and animals quarantined addition, these herds were located in high-­density cattle for an adequate length of time to confirm their sanitary status. areas, with most located within 1 km of other cattle farms. ‡Raising in specialised farms with animals of other farms. This cluster was also the one that most frequently shared §Rearing farm is under the official BVD/IBR control programme (ie, Livestock Health Defense Association) or equivalent to the official one. machinery and materials with other farms. The presence BDV, bovine viral diarrhoea; IBR, infectious bovine rhinotracheitis. of external workers was very rare. Farms mostly lacked 4 Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 Open access Table 3 Biosecurity measures related to vehicles and Table 4 Biosecurity measures related to visitors and staff equipment in 124 farms in Spain in 124 farms in Spain n (%) n (%) Shared feeder wagon (External) employees  No 48 (38.7)  No 68 (55.7)  Yes 76 (61.3)  Yes, but do not work in other farms 44 (34.4) Mean (median; Q1–Q3*) number of entries of 7.1 (7; 7–7)  Yes, and they work in other farms 12 (9.8) the feeder wagon per week, when shared Perimeter fence Shared machinery (tractors, wagons, cistern, slurry whisk, baler or others)  Yes, always closed 5 (4.1)  No 60 (47.5)  Yes, not always closed 8 (6.6)  Yes 64 (52.5)  No 111 (89.3) Shared manure vehicle Vehicle parking for visitors  No 103 (80.1)  Outside farm perimeter 4 (3.3)  Yes 21 (18.9)  Inside farm perimeter 120 (96.7) Mean (median; Q1–Q3) number of entries of 0.39 (0.17; 0.12–0.54) Mean (median; Q1–Q3*) number of visitors per month 7.2 (5; 3–9) the manure vehicle per month, when shared that can contact animals Shared materials (ear tag applicators, calving Visitors always use protective clothing† materials, cleaning materials, harvesting  Yes 9 (7.4) materials or others)  No 115 (92.6)  No 100 (80.3)  Yes 24 (19.7) *Q1: 25th percentile; Q3: 75th percentile. †Coveralls or overcoats and boots that are provided by the farmer Shared slurry vehicle before contacting cattle area.  No 82 (66.2)  Yes 42 (33.8) Cluster 2 (n=31) included herds also from Galicia, Mean (median; Q1–Q3) number of entries of 0.33 (0.08; 0.08–0.60) often of intermediate size (mean 63 cows). From the sani- the slurry vehicle per month, when shared tary point of view, seropositivity against BoHV-1 or BVDV  Carcase deposit area without evidence of recent or active infection was most  Outside farm perimeter 27 (20.5) frequently observed. These farms purchased animals  Inside farm perimeter 97 (79.5) less often than those in other clusters. When they did so, purchases often entailed few animals that were tested Mean (median; Q1–Q3) number of entries 0.34 (0.17; 0.12–0.51) of the carcase vehicle per month inside the against BVDV and BoHV-1. This was also the cluster with farm perimeter (when applicable) more control over the transport of purchased animals, avoiding contact with external cattle during transport. Vehicle (slaughter/feedlot) may arrive carrying animals from outside the farm As in the previous cluster, these farms were located in high-­density cattle areas, and most also had other small  No 5 (3.3) ruminant farms within 1 km. The feeder wagon was  Not known 5 (4.1) very frequently shared, being a vehicle that entered the  Yes 114 (92.6) farms daily (this particularity also occurred in cluster Vehicles (slaughter/feedlot) may enter inside 1, although at a lower proportion). Structures such as farm perimeter perimeter fencing or outdoor parking for visitors were  No 6 (4.9) also scarce. Numbers of external workers were interme-  Yes 118 (95.1) diate between those for clusters 1 and 3. Although cluster Mean (median; Q1–Q3) number of entries 2.6 (2; 1.5–5.3) 2 farms received, on average, less visitors than clusters 1 of the slaughter/feedlot vehicle per month and 3, the use of adequate protective clothing was still inside farm perimeter scarce. Cluster 3 (n=29) comprised all herds from Catalonia, *Q1: 25th percentile; Q3: 75th percentile. with the largest herds (mean 122 cows). This cluster had the highest proportions of active or recent infec- tions with BVDV and BoHV-1. Purchase of replacement structures such as perimeter fencing or outdoor parking. animals was most common, and the number of purchased Interestingly, they received numerous visitors despite animals was usually high. Notably, the 11 farms that their small size. Although the use of suitable protective purchased animals without any testing were included in clothing emerged as deficient in the entire sample of this cluster. Although infrequent, it was also the cluster farms, it was especially inadequate in this cluster. with the highest frequency of participation in cattle fairs Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 5 Open access Figure 1 Joint MCA plot of category points for the different biosecurity measures and the BVDV/BoHV-1 profiles that resulted from MCA. Frequencies of cattle purchases and entries of vehicles and visitors, each with four categories based on the quartiles of these frequencies, are not shown. BoHV-1, bovine herpesvirus 1; BVDV, bovine viral diarrhoea virus; MCA, multiple correspondence analysis. or contest. Farms in this cluster shared machinery or other populations.13 28 Appropriate quarantine facilities materials less frequently than did the smaller farms in were considered separate buildings and outside farm clusters 1 and 2, although manure vehicles were shared perimeter and with animals quarantined for an adequate much more often than in the other two. Structures such length of time to confirm their sanitary status (ie, to test as perimeter fencing or outdoor parking for visitors were the animals—if they have not been tested in origin or scarce, but nonetheless more frequent than in the other the transport conditions cannot be controlled—and at clusters. All cluster 3 farms employed external workers least until the laboratory results are received).22 Other who often worked also on other farms. The use of protec- movements that may pose a risk (ie, rental/shared bulls) tive clothing by visitors was also somewhat more common do not occur in the study population. In pasture, the in this cluster. concept of contact with other ruminants comprised any contact, either direct or indirect, with organic matter of DISCUSSION ruminants from other farms or with animals themselves The present study shows important shortcomings in (in pasture or as the ruminants were herded into the the application of biosecurity measures, particularly pasture). In the study population, the cows were consis- highlighting room for improvement of such measures tently herded into meadows in close vicinity of the farm controlling various potential routes of disease introduc- but, given the high density of farms in many of the areas tion. under observation, contact was likely to take place. Fortunately, many farms do not purchase animals, Several types of vehicles, especially feeding vehicles, reflecting a higher percentage of ‘closed’ herds than those frequently enter farms. Biosecurity measures related to described in other biosecurity studies in Europe,9 11–13 visitors should also be improved: for example, nearly 93 but still lower than that reported in Denmark, where 76.3 per cent of the farms could have visitors that have contact per cent of surveyed farms had not purchased animals with the animals and did not use protective clothing. in the previous year.16 Among those who do, there are Adequate protective clothing was defined as coveralls still farms that do not regularly assess the sanitary status or overcoats and boots that are provided by the farmer of these animals. The scarcity of quarantine facilities on before contacting the cattle area. A similar lack has farms is remarkable and has previously been observed in been observed on dairy farms in Europe,9 13 17 although 6 Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 Open access Figure 2 Clustered farms and their location on the multiple correspondence analysis chart. Two-­step cluster solution identifying three main clusters including 122 of the 124 study herds; the remaining two are shown in white in the centre of the chart. countries in Northern Europe reported better imple- also often receive courtesy visits from them, since such mentation of biosecurity measures in this regard.12 29 farms function with close links between the farm and the The implementation of biosecurity plans on dairy farms farmer’s own house, as has been described elsewhere.36 is voluntary in almost all countries. One exception within Despite the lack of several biosecurity measures, the the UE is Denmark.30 The biosecurity legislation in this proportion of such farms with recent or active BoHV-1 or country may have contributed to adoption of good bios- BVDV infection was low, possibly due to several factors. ecurity practices31 and has been recently extended from The most prominent refers to the nature of the aforemen- only large (>380 animals) to all farms.30 Regulation (EU) tioned BVD and IBR control programmes in Spain: these No 429/2016, which shall apply from 2021 and will affect are voluntary and executed only in some ACs. In Galicia EU animal health legislation, recognises and addresses and other regions in the north-­west and the Cantabric the importance of biosecurity.32 Therefore, farmers need area, such programmes are conducted mainly through to be motivated both to change existing behaviours and Livestock Health Defense Associations (known as ADSG to implement effective biosecurity practices to reduce the in Spanish) established by the regional governments in risk of disease introduction.33–35 2004. In Catalonia, these programmes are absent. MCA and TSCA show that there are three main farm Farms included in cluster 1 (and cluster 2) were all typologies in relation to the implementation of biose- from the Galicia region, where ADSGs included 55.2 per curity measures differentiated mainly by region (which cent of the herds and 65.0 per cent of Galician bovine implies different implementation of BVDV and BoHV-1 census and are therefore under BVD and IBR control control programmes) and herd size. Although some programmes.18 These programmes are based on sero- biosecurity limitations were common, others were more logical surveillance of herds and progressive reduction specific to each cluster, similar to the observation made of seroprevalence (mainly by controlling replacements; by Sarrazin and others.13 seropositive animals are not culled). Only in the case of Therefore, cluster 1 included the smallest herds in BVDV, when tested samples indicated possible persistent which low turnovers would pose a challenge to invest- infection (PI) in an animal (ie, when a positive result was ment, which may limit biosecurity (ie, these farms may obtained for a young heifer in serological test), the PI frequently be forced to share some vehicles, machinery or cattle was identified and eliminated, where appropriate. materials, and infrastructures such as perimeter fencing To prevent new infections, it is mandatory to test all or parking are scarce). Additionally, the high number of purchased animals against BVDV and BoHV-1 using estab- visitors they receive may be related to the fact that small lished protocols.22 This measure is controlled through farms more frequently require timely collaboration from the official register on livestock movements (REMO, by neighbouring farmers (eg, in the case of a calving). They its Spanish acronym), and the non-­performance of these Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 7 Open access tests implies economic penalties.22 However, for herds However, it is important to keep in mind that farmers in ADSG, there is no obligation over other biosecurity enrolled voluntarily in the study, and therefore the actions, although recommendations are provided to each results cannot be extrapolated directly to all dairy farms farm. in Spain due to possible selection bias. Farmers more Thus, the existence of control programmes has an concerned with biosecurity might have decided to partic- impact on the sanitary status of these farms; however, ipate in the project, resulting in over-­representation of apart from the control of purchased animals (manda- farms with relatively good implementation of biosecurity tory), the ADSG programmes do not seem to have measures in the sample. Additionally, the existence of significant influence on the application of many other voluntary ADSG BoHV-1 and BVDV control programmes measures concerning biosecurity (recommended but not in Galicia but not in other regions may have reduced the mandatory), judging by the critical deficiencies that have representative value of the sample. In addition, MCA is been observed. Although purchased cattle are consid- an exploratory method and interpretations of the results ered to be the main risk factor for disease entry to dairy may not extend to the magnitude of the effects of biose- farms,37–41 the importance of other measures should not curity measures on BVD and IBR status.44 be underestimated and may result in less use of monetary The study confirms previous perceptions that there and labour resources intended for control programmes. is a substantial lack in the application of biosecurity In cluster 2, the most frequent sanitary status was measures,17 even on farms under sanitary programmes. the presence of seropositive animals without evidence The fact that there are still herds that introduce untested of recent or active infections. In the case of BVDV, the animals and that there is lack of quarantine facilities in percentage of farms with active infection is higher than most farms indicates that there is a need for improve- in cluster 1, although still far from that observed in ment in this regard. Additionally, in view of the frequency cluster 3. The virus is more likely to persist over time in of non-­farm and shared vehicles entering inside farm larger herds. Viral persistence may increase with herd perimeter, measures should be taken to reduce these size because self-­clearance may be more frequent in small entries to essential ones and when necessary cleaning and herds due to stochastic events.42 disinfection programmes should be followed for these Cluster 3 included the largest herds in the study, vehicles. Visitor control, and the associated biosecurity located in Catalonia. Herd size has been previously measures (ie, use of protective clothing), also appears described as a cluster variable for several biosecurity risks to be a priority, given the observed deficiencies and the such as increased purchase of animals, increased visitors small distances to neighbouring farms (most farms had (veterinary practitioners, technicians) and the presence other cattle farms within 1 km). This survey also high- of external workers, all of which will increase the likeli- lights regional and herd size-­related differences in the hood of disease introduction and maintenance.24 Cluster implementation of biosecurity measures. 3 farms in the present study met all these characteristics In Spain, regional and national governments are and often introduced animals without testing. Relevantly, increasingly involved in generating debate, awareness as mentioned, no official control programme has been campaigns and training in promoting the implementa- established in this region. Thus, although some biosecu- tion of biosecurity as a previous step to develop specific rity facilities or biosecurity measures were more frequent legislation to force farmers to implement some recom- in these farms than in the other two clusters, cluster 3 mendations.36 Despite the inherent limitations of this showed the poorest sanitary level, especially in relation study the authors believe it to have provided a compre- to BVDV. hensive overview of the main biosecurity shortcomings Additionally, it should be noted that when comparing in the dairy sector of Spain and to identify clusters in clusters 1 and 2, it was observed that farms that purchase terms of biosecurity measures and sanitary status. Such animals were somewhat more numerous in cluster 1, data should be useful to focus training and awareness so herd size and number of animal purchases were not programmes and to improve risk reduction strategies in directly related in these two clusters. The smallest farms this economically important industry. sometimes combine dairy production with other profes- sional activities, using dairy farming to supplement family Author affiliations income.43 Thus, the lack of labour and even facilities for 1 ADSG Costa da Morte, A Coruña, Spain 2 rearing heifers could explain the higher frequency of Serology, Animal Health and Production Laboratory of Galicia, Lugo, Spain 3 Department of Helath ans Animal Anatomy, Universitat Autònoma de Barcelona, purchases than larger farms in cluster 2. Barcelona, Catalunya, Spain The influence of the study’s methodology on these 4 Animal Health Service, Animal Health Laboratory of Catalonia, Lleida, Spain results must be considered. Questionnaires were 5 Dairy Interprofessional Laboratory of Catalonia, Cabrils, Barcelona, Spain 6 completed during face-­to-­face interviews on farms in the Animal Health Department, Universidad de Nariño, San Juan de Pasto, Colombia 7 presence of the veterinarian responsible for the sanitary Department of Helath ans Animal Anatomy, Autonomous University of Barcelona, Barcelona, Catalunya, Spain programme of the farm. This enabled clear explanation of 8 Sanidad y Anatomia Animal, Universidad Autonoma de Barcelona, Barcelona, questions and control of bias related to social desirability Catalonia, Spain response, although the authors may have been able to 9 Epidemiologia, Centre de Recerca en Sanitat Animal (CReSA), UAB, IRTA, obtain a larger sample size using mailed questionnaires. Barcelona, Catalonia, Spain 8 Villaamil FJ, et al. Vet Rec Open 2020;7:e000399. doi:10.1136/vetreco-2020-000399 Open access 10 Institute of Food Analysis and Research, Santiago de Compostela University, Lugo, measures for cattle and swine farms in Switzerland. PLoS One Spain 2015;10:e0144533. 11 Animal Production, University of Santiago de Compostela, Lugo, Galicia, Spain 15 Shortall O, Ruston A, Green M, et al. Broken biosecurity? veterinarians' framing of biosecurity on dairy farms in England. Prev Vet Med 2016;132:20–31. Acknowledgements The authors want to thank all the farmers and veterinarians 16 Oliveira VHS, Sørensen JT, Thomsen PT. Associations between involved in the study. biosecurity practices and bovine digital dermatitis in Danish dairy herds. J Dairy Sci 2017;100:8398–408. Contributors FJV, BB: biosecurity data and sample collection. IA: serological 17 Renault V, Humblet MF, Moons V, et al. Rural veterinarian's and virological analysis. AA: collating biosecurity information and writing and perception and practices in terms of biosecurity across three revising the manuscript. MM, ML: serological analysis. SMD, YC: literature review European countries. Transbound Emerg Dis 2018;65:e183–93. and revising the manuscript. EY: biosecurity data collection, literature review and 18 Arnaiz I, Eiras C, Carnero MI. 15 años de programa de control revising the manuscript. FJD: data analysis, writing and revising the manuscript. voluntario frente al IBR en galicia: situación ante un programa de erradicación. XXIII Congreso Internacional de medicina bovina Funding This research was supported by a project from the Ministry of Science Anembe; Vigo, 2018: 348–9. and Innovation of Spain (AGL2016-77269-­C2-2-­R). 19 European Commission. Commission implementing decision (EU) Competing interests None declared. 2017/486 of 17 March 2017 amending annexes I and II to decision 2004/558/EC. Available: https://​eur-​lex.​europa.​eu/​legalcontent/​EN/​ Provenance and peer review Not commissioned; externally peer reviewed. TXT/?​qid=​1556212590594&​uri=​CELEX:​32017D0486 20 Pinior B, Firth CL, Richter V, et al. A systematic review of financial Data availability statement All data relevant to the study are included in the and economic assessments of bovine viral diarrhea virus (BVDV) article or uploaded as supplementary information. Manuscript data uploaded as prevention and mitigation activities worldwide. Prev Vet Med Excel file. 2017;137:77–92. Open access This is an open access article distributed in accordance with the 21 Ministerio de Agricultura y Pesca, Alimentación y Medio Ambiente (MAPAMA). Panel situación sector lácteo España. Available: http:// Creative Commons Attribution Non Commercial (CC BY-­NC 4.0) license, which www.​mapama.​gob.​es/​es/​ganaderia/​temas/​produccion-​y-​mercados-​ permits others to distribute, remix, adapt, build upon this work non-­commercially, ganaderos/​pizarraabril18_​tcm30-​444377.​pdf and license their derivative works on different terms, provided the original work is 22 Diario Oficial de Galicia (DOGA). ORDEN de 27 de diciembre de properly cited, an indication of whether changes were made, and the use is non-­ 2017 POR La que se establecen LAS bases reguladoras de las commercial. See: http://​creativecommons.​org/​licenses/​by-​nc/​4.​0/. ayudas a LAS entidades reconocidas como agrupaciones de defensa sanitaria ganaderas (ADSG) de galicia Y se convocan para ORCID iD El año 2018-2019. Available: https://www.​xunta.​gal/​dog/​Publicados/​ Francisco J Dieguez http://​orcid.​org/​0000-​0003-​3642-​481X 2018/​20180117/​AnuncioG0426-​271217-​0003_​es.​html 23 Bolin SR, Ridpath JF. 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