Identification of discriminating behavioural and movement variables in lameness scores of dairy cows at pasture from accelerometer and GPS sensors using a Partial Least Squares Discriminant Analysis.

The behaviour and movement of lame dairy cows at pasture have been studied little, yet they could be relevant to improve the automatic detection of lameness in cows in pasture-based systems. Our aim in this study is to identify behavioural and movement variables of dairy cows at pasture that could discriminate lameness scores. Individual cow behaviours were predicted from accelerometer data and movements measured using GPS data. Sixty-eight dairy cows from three pasture-based commercial farms were equipped with a 3-D accelerometer and a GPS sensor fixed on a neck collar for 1-5 weeks, depending on the farm, in spring and summer 2018. A lameness score was assigned to each cow by a trained observer twice a week. Behaviours were predicted every 10 s based on accelerometer data, and then combined with the GPS position. Segmentation on behavioural time series was used to delineate each behavioural bout within each outdoor period. Thirty-seven behavioural and movement variables were then calculated from the behavioural bouts for each cow. A partial least square discriminant analysis was performed to identify the variables that best discriminate lameness scores. Time spent grazing, grazing bout duration, duration before lying down in the pasture, time spent resting, number of resting bouts, distance travelled during grazing, and dispersion were the most discriminant variables in the PLS-DA (VIP > 1). Severely lame cows spent 4.5 times less time grazing and almost twice as much time resting as their sound congeners, especially in the lying position. Exploratory behaviour was also reduced for both moderately and severely lame cows, resulting in 1.2 and 1.7 times less distance travelled respectively, especially during grazing. These variables could be used as additional variables to improve the performance of existing lameness detection devices in pasture-based systems.

Short communication: Informative value of an ELISA applied to bulk tank milk to assess within-herd prevalence of digital dermatitis in dairy herds.

The objective of this study was to assess whether an antibody ELISA applied to bulk tank milk (BTM) could be used to accurately estimate within-herd prevalence of digital dermatitis (DD). The ELISA was designed for the detection of antibodies against Treponema phagedenis-like strain V1 (PrrA antigen). The hind feet of all lactating cows from 40 commercial French dairy herds with a history of DD were scored by an observer in the milking parlor, using the 4 M-stage system. After milking, a BTM sample was collected and tested for anti-Treponema phagedenis-like antibodies using the antibody ELISA. Within-herd DD prevalence at the cow level was determined using 2 different approaches: (1) having DD lesion on at least 1 hind foot (Prev; prevalence of affected cows), and (2) having an M1 or M2 lesion on at least 1 hind foot (PrevA; prevalence of cows affected by DD in an active stage). Receiver operating characteristic analysis was used to determine both optimal within-herd DD prevalence and BTM sample to positive (S/P) ratio cut-off values. Two optimal cut-off values were identified. Herds with an S/P ratio of BTM ≤0.2 had a Prev ≤10% (sensitivity = 0.97, specificity = 1), whereas herds with an S/P ratio of BTM >0.38 had a Prev >40% (sensitivity = 0.94, specificity = 0.86). In the same way but with a slightly lower specificity, an S/P ratio >0.38 corresponds also to a PrevA >18% (sensitivity = 0.92, specificity = 0.70). The BTM antibody ELISA shows great promise for screening purposes during DD management programs.

Evaluation of a biocide footbath solution in the occurrence and healing of digital dermatitis lesions in dairy cows: A clinical trial.

The objective of this study was to evaluate the effect of the implementation of different footbathing practices using a new biocide solution (Pink-Step™, Qalian, France) in the healing and the occurrence of bovine digital dermatitis (bDD) lesions. The investigation was conducted through a controlled within cow clinical trial in which the hind feet of cows from each farm were allocated either to the control group or to a moderate (MR) or (IR) intensive footbath-regimen groups. The trial involved 1036 cows (2072 feet) from 10 dairy farms located in western France where bDD was endemic. Split-footbaths were placed at the exit of the milking parlor of each farm, allowing the biocide to be administered to one side of the cows while using the other empty side as a negative control. The administration frequency for MR was of 2 days/week/1st-month, then 2 days/2 weeks/2nd-month, and then 2 days/month, and for IR was of 2 days/week/1st-2nd months, and then 2 days/2 weeks. Footbaths were administered during 140 days (approx.), and feet were evaluated for the at least once a month in the milking parlor. Nested survival models were used to estimate the relative impact of the footbath regimens and other concomitant risk factors on the time that bDD lesions occurred or healed. No effect of Pink-Step™ was evidenced on the bDD occurrence during the trial. The risk for bDD occurrence was increased by poor feet cleanliness at both the cow (HR 1.69, CI 1.21-2.39) and farm level (HR 2.06, CI 1.44-2.94). Otherwise, the use of Pink-Step™ in an IR was effective in improving the healing of bDD lesions (HR 1.79, CI 1.12-2.88). The time to healing was also improved in inactive lesions (HR 2.19, CI 1.42-3.37). Conversely, the time to healing was delayed in feet receiving hoof-trimming (HR 0.41, CI 0.26-0.62), in cows with a contralateral bDD lesion (HR 0.32, CI 0.22-0.46) or in late lactation (HR 0.61, CI 0.43-0.85), and finally in farms with more than 100 cows (HR 0.48, CI 0.34-0.67). These findings reinforce the crucial role of hygiene in bDD dynamics and highlight the importance of implementing multiple control measures simultaneously, such as hygiene improvements in the barn, early detection and treatment of bDD lesions and the correct usage of individual and collective treatments. The implementation of Pink-Step™ represents a promising strategy for reducing the persistence of bDD lesions in affected herds.

A large outbreak of bovine botulism possibly linked to a massive contamination of grass silage by type D/C Clostridium botulinum spores on a farm with dairy and poultry operations.

Type D bovine botulism outbreaks associated with poultry litter are increasingly reported in European countries, but the circumstances of exposure to Clostridium botulinum toxins remain unclear. In spring 2015, a large type D/C bovine botulism outbreak affected a farm with dairy and poultry operations. Epidemiological and laboratory investigations strongly suggest that the outbreak was caused by feeding cattle with insufficiently acidified grass silage that was contaminated by type D/C C. botulinum spores. The source of the spores remains unclear, but could have been a stack of poultry litter stored in the grass silage pasture before harvesting. The presence of putrefied poultry carcasses mixed in with the litter is relatively unlikely considering the careful daily removal of poultry carcasses. These findings reinforce the importance of proper ensiling of feed materials and highlight the need for safe disposal of poultry litter, even in the case of good management of poultry deadstock, in order to prevent bovine botulism.

Exploring pig trade patterns to inform the design of risk-based disease surveillance and control strategies.

An understanding of the patterns of animal contact networks provides essential information for the design of risk-based animal disease surveillance and control strategies. This study characterises pig movements throughout England and Wales between 2009 and 2013 with a view to characterising spatial and temporal patterns, network topology and trade communities. Data were extracted from the Animal and Plant Health Agency (APHA)'s RADAR (Rapid Analysis and Detection of Animal-related Risks) database, and analysed using descriptive and network approaches. A total of 61,937,855 pigs were moved through 872,493 movements of batches in England and Wales during the 5-year study period. Results show that the network exhibited scale-free and small-world topologies, indicating the potential for diseases to quickly spread within the pig industry. The findings also provide suggestions for how risk-based surveillance strategies could be optimised in the country by taking account of highly connected holdings, geographical regions and time periods with the greatest number of movements and pigs moved, as these are likely to be at higher risk for disease introduction. This study is also the first attempt to identify trade communities in the country, information which could be used to facilitate the pig trade and maintain disease-free status across the country in the event of an outbreak.

Multivariate analysis of traditional pig management practices and their potential impact on the spread of infectious diseases in Corsica.

Corsica is a French Mediterranean island with traditional extensive pig farming oriented towards the production of high quality cured meat products. The increasing success of these cured products in continental Europe has triggered the development and organisation of an extensive pig farming industry. However, these pig farming practices have seldom been described and analysed to understand the potential risk of introduction and spread of infectious diseases. We conducted a cross-sectional study in Corsica in 2013 to characterise the main pig management practices and to identify groups of farms with similar practices and therefore homogeneous risk of introduction and spread of infectious diseases. We interviewed 68 pig farmers and investigated different farm management practices which could lead to contact between herds, such as trading animals, sharing pastures, feed and reproduction management (direct contacts), slaughtering and carcass waste management, and contacts with people and vehicles (indirect contacts). The practices were described and the farms grouped by multiple factor and hierarchical clustering analyses. Results revealed interesting patterns in the introduction and spread of infectious disease, such as the seasonality of pig production, the potential local spread of diseases in pastures due to the presence of free-ranging boars, carcasses, and animal waste. Multivariate analyses identified four groups of farms with different levels of risk of the spread of infectious disease, illustrating changes in farmers' customs from free-range uncontrolled farming systems to more controlled systems aimed at the production of high quality pork products. These results will be useful to more realistically simulate the spread of infectious diseases among Corsican pig farms and highlight the need for awareness raising campaigns among the stakeholders to reduce risky practices.

Farmers' practices, motivators and barriers for adoption of treatments of digital dermatitis in dairy farms.

This study aimed to catalogue the digital dermatitis (DD) treatment practices used by French dairy farmers and to identify the motivators and barriers to the adoption of these treatments. A semi-structured survey was conducted involving 65 farmers in the main dairy production areas of France in the spring of 2009. The different treatment modalities implemented by farmers since the first diagnosis of DD in their herds were described. The reasons for adopting or abandoning these treatments were then investigated based on criteria of perceived effectiveness, labour, time, cost and toxicity related to their use. For individual treatments, farmers used 30 different products, applied through three different routes, for 1 to 21 consecutive days. For collective treatments, farmers used 31 products, applied through four different routes, at a rate ranging from once a day to once a year. Several products, especially antibiotics, were used without observing the manufacturer's instructions. The principal criteria for the adoption of a treatment was the perceived effectiveness in healing DD lesions and in limiting recurrence, while the principal barriers to adopting a treatment were the time and labour required for its application, followed by cost. Topical oxytetracycline treatments applied individually were used and adopted the most. They were perceived to be effective in healing DD lesions. However, these treatments were judged labour and time consuming, particularly when many animals had to be treated. Collective treatments combining formalin and copper sulphate often were applied topically using walk-though footbaths. These treatments often were judged to be insufficiently effective in healing DD lesions, difficult to implement, labour and time consuming and costly. The plethora of DD treatment practices and the misuse of some treatments could suggest that there is a lack of guidelines available to farmers on the optimal use and expected effectiveness of treatments. Clinical trials should be conducted to develop recommendations based on scientific rather than empirical data, and to identify the DD control measures which consume the least amount of time and labour.

Estimation of the relative impact of treatment and herd management practices on prevention of digital dermatitis in French dairy herds.

The purpose of this study was to concurrently estimate the effect of different digital dermatitis (DD) treatment regimens and herd management practices on the occurrence of a new DD lesion. A controlled clinical trial was conducted and involved 4678 dairy cows from 52 French dairy farms where DD was endemic. Farms were allocated by minimisation to one of 4 treatment regimens, varying through the mode (footbath or collective spraying) and the frequency of application (2 days every 4 weeks or fortnightly). They were visited 7 times every 4 weeks by 14 trained investigators. Frailty Cox proportional hazards models were used to estimate the relative effect of potential risk factors and treatment practices on the time until the first occurrence of a DD lesion. At herd level, high initial DD prevalence strongly increased the risk for DD occurrence (HR=1.93, CI 1.23-3.04), as well as absence of hoof-trimming (HR=1.75, CI 1.36-2.27) and poor leg cleanliness (HR=2.44, CI 1.80-3.31). At animal level, Holstein breed (HR=1.92, CI 1.35-3.57) and high-productive cows (HR=1.26, CI 1.01-1.56) were identified to be at higher risk for DD compared to Normande breed and low-productive cows, respectively. Compared to individual topical antibiotic treatments alone, collective treatments tended to decrease the risk of DD occurrence only when applied over 2 days at least every fortnight (HR range=0.64-0.73).

Association between digital dermatitis lesions and test-day milk yield of Holstein cows from 41 French dairy farms.

The objective of this study was to estimate the association between digital dermatitis (DD) lesions and test-day milk yield (TDY) in dairy cows, taking into account the severity of the lesions. Data were collected for 6 mo on 47 French dairy farms endemically affected by DD and involved in a clinical trial aiming to assess the effectiveness of collective treatments against DD. The hind feet of all lactating cows were scored for DD by 14 trained investigators on a monthly basis using a 4-point M-stage scoring system (M0 to M4, M standing for Mortellaro). The DD status was defined in 3 categories at the animal level: no DD [scores of M0 and (or) M4 on both feet], moderate case (score of M1 on 1 or both feet and no M2 score), and severe case (score of M2 on 1 or both feet). All monthly TDY in the lactation were collected. The final complete data set included 7,599 TDY of 1,782 Holstein cows from 41 herds. The effect of DD lesions on the following TDY (i.e., within 30 d after detection of a DD lesion) was analyzed separately for primiparous and multiparous cows, using mixed-models ANOVA, with TDY as repeated measures. During the trial, 38% of the primiparous and 41% of the multiparous cows were observed at least once with a DD lesion (moderate or severe case), the cows being observed with a DD lesion, on average, for 2 consecutive visits. Milk yield decreased significantly for cows diagnosed with a DD lesion. Primiparous cows produced, on average, 0.63 kg/d less when DD was moderate and 0.50 kg/d less when the disease was severe, compared with unaffected cows. Multiparous cows produced, on average, 0.50 kg/d less when DD was moderate and 0.75 kg/d less when the disease was severe, compared with unaffected cows. These results confirm that DD lesions have a significant effect on the milk yield of dairy cows, including when animals are rigorously treated. Milk yield losses, thus, should be considered when evaluating the costs and benefits of DD control programs.

Effectiveness of different regimens of a collective topical treatment using a solution of copper and zinc chelates in the cure of digital dermatitis in dairy farms under field conditions.

A controlled field trial was conducted to evaluate in dairy cattle the benefit provided by different regimens of a collective topical treatment using a solution of copper and zinc chelates to cure digital dermatitis (DD) compared with individual treatment alone, and further to investigate factors that could explain variations in the clinical cure of DD lesions over 6 mo. The study was conducted between November 2009 and October 2010 and involved 4,677 dairy cows from 52 French dairy farms on which DD was endemic. The farms were quasi-randomly allocated to 1 of 4 treatment regimens for 6 mo: no collective treatment (control), walk-through footbath during 4 consecutive milkings every 4 wk (FB/4W) or every 2 wk (FB/2W) and collective spraying during 2 milkings every 2 wk (CS/2W). For ethical and welfare reasons, all farmers also had to treat all detected active DD lesions with individual topical spraying of oxytetracycline. Digital dermatitis and leg hygiene were scored on all lactating cows during milking 7 times every 4 wk by 14 trained investigators. During these farm visits, data related to farm management were also collected. The curative effectiveness of collective treatments was assessed through a Cox survival frailty model as the probability of cure of an active DD lesion during at least 2 consecutive visits. The model was adjusted for farm and cow risk factors as well as initial DD prevalence. Monthly DD cure rates were 58, 55, 76, and 76% in the control, FB/4W, FB/2W, and CS/2W regimens, respectively. The spontaneous monthly cure rate for untreated active DD lesions was 61%. Hazard of cure of DD was increased by 1.28 and 1.41 when walk-through footbath and collective spraying, respectively, were applied over 2 d every 2 wk compared with the control regimen. Applying a walk-through footbath 2 d every 4 wk was not sufficient to improve the cure of DD compared with individual treatments alone. Three main factors were identified as speeding DD healing: cleanliness of the feet, initial small size of the DD lesion, and additional individual topical treatment. Grazing tended to speed DD healing. These results highlight the need of combining several control measures, including individual and collective topical treatments, and improving foot hygiene and the early detection of DD lesions to ensure a high cure rate and rapid curing of digital dermatitis on endemically affected farms.

A simple method to score digital dermatitis in dairy cows in the milking parlor.

The diagnosis of digital dermatitis (DD) in cows is crucial for researchers to evaluate the effectiveness of control measures. The objective of this study was to evaluate intra- and inter-observer agreement and accuracy of a simple method to score DD lesions that is based on the inspection of cleaned feet in the milking parlor with a swiveling mirror and a powerful headlamp. The hind feet of 242 Holstein cows from 4 farms were inspected concurrently by 5 observers (to assess inter-observer agreement) during 2 consecutive milkings (to assess intra-observer agreement). This inspection was followed by an inspection of the feet in a trimming chute, considered to be the gold standard test, to test for accuracy. The reliability of the method was assessed using both the 5 M-stages scoring system (M0 to M4, M standing for Mortellaro) and a simplified M-stages scoring system in which the M3 and M4 stages are merged. As most disagreements concerned the M3 and M4 stages, performance was improved with the simplified M-stages scoring system. With this simplified system, the method had good intra-observer agreement [percent of overall raw agreement (PA)=80%, weighted kappa (κ(w))=0.71, and good inter-observer agreement (PA=77%, κ(w)=0.66)]. The agreement with the gold standard test was moderate (PA=69%, κ(w)=0.58). Considering absence versus presence of a DD lesion on a foot, the method had good sensitivity (0.90) and specificity (0.80). The time spent for inspection varied from 30 to 60s per cow. Inspection of cleaned feet with a swiveling mirror and a powerful headlamp in the milking parlor is a reliable, cost- and time-friendly method, which may be useful for both farmers and researchers, especially when the DD status of many dairy cows has to be evaluated concomitantly. The reliability of this method might be improved by using more precise descriptive criteria for the discrimination of each M-stage.