Short communication: Accuracy of estimation of lameness, injury, and cleanliness prevalence by dairy farmers and veterinarians

Problems with Congestive Heart Failure and Lameness That Have Increased in Grain-Fed Steers and Heifers

Grain-fed steers and heifers have increasing problems with both lameness and congestive heart failure. Congestive heart failure used to be limited to cattle raised at high altitudes. It is now occurring at much lower elevations. An inspection of hearts at the slaughter plant indicated that some groups of grain-fed steers and heifers had abnormally swollen hearts in 34% of the animals. Congestive heart failure may also increase death losses in the late stages of the feeding program. Lameness has also increased to 8% of grain-fed steers and heifers arriving at U.S. slaughter plants. Twenty years ago, observations by the author indicated that lameness in fed cattle arriving at the slaughter plant was almost zero. There has also been an increasing occurrence of abnormal hoof structure and poor leg conformation. Genetic selection for rapid growth and a large ribeye may be associated with the increase in both of these problems. Lameness and heart problems severely compromise animal welfare.

Global losses due to dairy cattle diseases: A comorbidity-adjusted economic analysis

An economic simulation was carried out over 183 milk-producing countries to estimate the global economic impacts of 12 dairy cattle diseases and health conditions: mastitis (subclinical and clinical), lameness, paratuberculosis (Johne's disease), displaced abomasum, dystocia, metritis, milk fever, ovarian cysts, retained placenta, and ketosis (subclinical and clinical). Estimates of disease impacts on milk yield, fertility, and culling were collected from the literature, standardized, meta-analyzed using a variety of methods ranging from simple averaging to random-effects models, and adjusted for comorbidities to prevent overestimation. These comorbidity-adjusted disease impacts were then combined with a set of country-level estimates for lactational incidence or prevalence or both, herd characteristics, and price estimates within a series of Monte Carlo simulations that estimated and valued the economic losses due to these diseases. It was estimated that total annual global losses are US$65 billion (B). Subclinical ketosis, clinical mastitis, and subclinical mastitis were the costliest diseases modeled, resulting in mean annual global losses of approximately US$18B, US$13B, and US$9B, respectively. Estimated global annual losses due to clinical ketosis, displaced abomasum, dystocia, lameness, metritis, milk fever, ovarian cysts, paratuberculosis, and retained placenta were estimated to be US$0.2B, US$0.6B, US$0.6B, US$6B, US$5B, US$0.6B, US$4B, US$4B, and US$3B, respectively. Without adjustment for comorbidities, when statistical associations between diseases were disregarded, mean aggregate global losses would have been overestimated by 45%. Although annual losses were greatest in India (US$12B), the United States (US$8B), and China (US$5B), depending on the measure of losses used (losses as a percentage of gross domestic product, losses per capita, losses as a percentage of gross milk revenue), the relative economic burden of these dairy cattle diseases across countries varied markedly.

Lameness prevalence in lactating and dry cows - expert's, student's and farmers' assessments

OBJECTIVE

The aim of this study was to evaluate differences in lameness prevalence among Austrian dairy farms for both lactating and dry cows as assessed by locomotion scoring (LCS 1-5) by an expert and a student who had received brief training in locomotion scoring and by farmers' estimates and by farmers' lameness assessments.

MATERIALS AND METHODS

In total, 632 cows from 11 farms were evaluated, including 553 lactating and 79 dry cows. Lameness prevalence was calculated for all farms collectively as well as for individual farms. The ratio of lameness prevalence determined by the student/expert (Student's Assessment Index: SAI), the ratio between farmers' assessments/expert assessments (Farmers' Assessment Index: FAI) and the ratio between farmers' estimates/expert assessments (Farmers' Detection Index: FDI) were calculated.

RESULTS

For the expert, the mean lameness prevalence (LCS≥2) among all 632 cows was 63.1%, while for the student it was 60.2%, and the farmers' assessment was 37.3%, resulting in a mean difference of 25.8% between the expert and the farmers. In cows with LCS 2, the SAI was 99.6%, in cows with LCS 3, it was 84.4%, and in cows with LCS≥4, it was 88.6%. The mean FDI and FAI for all cows on the 11 farms were 35.1% and 58.2%, respectively, with wide variation across farms (6.8-79.1% and 17.8-94.7%, respectively). Overall, lactating and dry cows exhibited a high mean lameness prevalence (63.9% vs. 59.6%), which differed by only 4.3%.

CONCLUSIONS AND CLINICAL RELEVANCE

Farmers should actively assess their cattle for lameness on a regular basis. Moreover, they should be trained to identify lame cows (lactating and dry cows), especially those showing mild lameness (LCS 2). Since the recently trained student achieved similar high recognition rates as the expert, it is assumed that a training in locomotion scoring can contribute to higher recognition rates.

Comparison of Antibiotic Use and the Frequency of Diseases Depending on the Size of Herd and the Type of Cattle Breeding

Diseases are responsible for losses in livestock production by increasing animal mortality and reducing productivity. The administration of antibiotics can help mitigate these negative effects. However, inappropriate use can lead to severe complications, such as raising antibiotic resistance. The purpose of this study was to perform a comparative analysis of antibiotic use and disease frequency over four years, based on the size of dairy farms and the type of farm. The study covered a 4-year period and included medium dairy farms (20-50 cows, n = 13), large dairy farms (>250 cows, n = 8), and large beef farms (n = 8). The collected data involved antimicrobial use but also included farm demographics, animal health, disease frequency, and herd management practices. The criteria used to categorise antibiotics into groups A-D were based on the EMA guidelines. The carried-out study showed that the large dairy cattle farms had the highest antibiotic consumption (18.29 mg·PCU-1), due to the high frequency of diseases, and consequently, the treatment of calf (diarrhoea, lung inflammations) and cow diseases (general treatment and mastitis). Cattle on large beef farms suffer mainly from general diseases caused by maintenance and herd management conditions. The use of restrict antibiotics was, in some cases, unjustified (antibiotics for dry cow therapy). Future studies should consider a larger number of farms, taking into account the given direction of cattle production.

Application of Epidemiological Methods in a Large-Scale Cross-Sectional Study in 765 German Dairy Herds-Lessons Learned

From 2016 to 2020, the "PraeRi" study, conducted by three German veterinary universities, was aimed at enhancing animal health and welfare in dairy farms. With 765 dairy farms visited and 101,307 animals examined, this study provided a basis for improving animal health and welfare. The study population comprised three different regions representing a broad variety of characteristics. To ensure representative estimates, a sample size of 250 farms was determined for each region, employing a stratified sampling plan based on farm size. According to the information provided by the farmers, the most commonly occurring disease in their herds was mastitis without general disorder (14.2% to 16.3% of the herd-depending on the region). For most disorders, prevalence data were lowest for the region South compared with the two remaining regions. Multivariable regression analyses were performed to identify risk factors for various target variables, and the results were communicated through individual reports and benchmarking flyers to participating farmers. The authors encountered challenges in management and communication due to the project's size in terms of personnel, data, and farms examined. Harmonizing data management and hypothesis testing across all involved parties added complexity.

Crowd sourcing remote comparative lameness assessments for dairy cattle

Lameness assessments are rarely conducted routinely on dairy farms and when completed typically underestimate lameness prevalence, hampering early diagnosis and treatment. A well-known feature of many perceptual tasks is that relative assessments are more accurate than absolute assessments, suggesting that creating methods that allow for the relative scoring of which cow is more lame will allow for reliable lameness assessments. Here we developed and tested a remote comparative lameness assessment method: we recruited nonexperienced crowd workers via an online platform and asked them to watch 2 videos side-by-side, each showing a cow walking, and to identify which cow was more lame and by how much (on a scale of -3 to 3). We created 11 tasks, each with 10 video pairs for comparison, and recruited 50 workers per task. All tasks were also completed by 5 experienced cattle lameness assessors. We evaluated data filtering and clustering methods based on worker responses and determined the agreement among workers, among experienced assessors, and between these groups. A moderate to high interobserver reliability was observed (intraclass correlation coefficient, ICC = 0.46 to 0.77) for crowd workers and agreement was high among the experienced assessors (ICC = 0.87). Average crowd-worker responses showed excellent agreement with the average of experienced assessor responses (ICC = 0.89 to 0.91), regardless of data processing method. To investigate if we could use fewer workers per task while still retaining high agreement with experienced assessors, we randomly subsampled 2 to 43 (1 less than the minimum number of workers retained per task after data cleaning) workers from each task. The agreement with experienced assessors increased substantially as we increased the number of workers from 2 to 10, but little increase was observed after 10 or more workers were used (ICC > 0.80). The proposed method provides a fast and cost-effective way to assess lameness in commercial herds. In addition, this method allows for large-scale data collection useful for training computer vision algorithms that could be used to automate lameness assessments on farm.

Prevalence of lameness in dairy cows: A literature review

Lameness in dairy cows has major negative impacts on animal welfare and production economy. While previous studies have evaluated the prevalence of lameness in single countries, the present literature review is the first overview of the prevalence of lameness in dairy cows globally. This literature review identified 53 studies reporting prevalence of lameness among representative samples of dairy cows and fulfilling a number of specified inclusion criteria (e.g., at least 10 herds and 200 cows, and locomotion scoring by trained observers). A total of 414,950 cows from 3945 herds were included in these 53 studies, which spanned a 30-year period (1989-2020) and included herds from six continents, with the majority from Europe and North America. Across the studies, the mean prevalence of lameness (typically defined as score 3-5 on a 1-5 scale) was 22.8% with a median of 22.0% and a range between studies from 5.1% to 45%, and a within herd range from 0% to 88%. The mean prevalence of severely lame cows (typically defined as score 4-5 on a 1-5 scale) was 7.0% with a median of 6.5% and a range between studies from 1.8% to 21.2%, and a within herd range from 0% to 65%. Over time, it appears that the prevalence of lameness has changed very little. Several different locomotion scoring systems and definitions of (severe) lameness were used across the 53 studies, and this may have affected the reported lameness prevalence. Sampling of herds and cows, inclusion criteria and representativeness also differed between studies. This review offers recommendations for the future capture of information on lameness in dairy cows and identifies potential knowledge gaps.

Cost of lameness in dairy herds: An integrated bioeconomic modeling approach

Foot disorders are costly health disorders in dairy farms, and their prevalence is related to several factors such as breed, nutrition, and farmer's management strategy. Very few modeling approaches have considered the dynamics of foot disorders and their interaction with farm management strategies within a holistic farm simulation model. The aim of this study was to estimate the cost of foot disorders in dairy herds by simulating strategies for managing lameness. A dynamic and stochastic simulation model (DairyHealthSim) was used to simulate the herd dynamics, reproduction management, and health events. A specific module was built for lameness and related herd-level management strategies. Foot disorder occurrences were simulated with a base risk for each etiology [digital dermatitis (DD), interdigital dermatitis, interdigital phlegmon, sole ulcer (SU), white line disease (WLD)]. Two state machines were implemented in the model: the first was related to the disease-induced lameness score (from 1 to 5), and the second concerned DD-state transitions. A total of 880 simulations were run to represent the combination of the following 5 scenarios: (1) housing (concrete vs. textured), (2) hygiene (2 different scraping frequencies), (3) the existence of preventive trimming, (4) different thresholds of DD prevalence detected and from which a collective footbath is applied to treat DD, and (5) farmer's ability to detect lameness (detection rate). Housing, hygiene, and trimming scenarios were associated with risk factors applied for each foot disorder etiologies. The footbath and lameness detection scenarios both determined the treatment setup and the policy of herd observance. The economic evaluation outcome was the gross margin per year. A linear regression model was run to estimate the cost per lame cow (lameness score ≥3), per case of DD and per week of a cow's medium lameness duration. The bioeconomic model reproduced a lameness prevalence varying from 26 to 98% depending on the management scenario, demonstrating a high capacity of the model to represent the diversity of the field situations. Digital dermatitis represented half of the total lameness cases, followed by interdigital dermatitis (28%), SU (19%), WLD (13%), and interdigital phlegmon (4%). The housing scenarios dramatically influenced the prevalence of SU and WLD, whereas scraping frequency and threshold for footbath application mainly determined the presence of DD. Interestingly, the results showed that preventive trimming allowed a better reduction in lameness prevalence than spending time on early detection. Scraping frequency was highly associated with DD occurrence, especially with a textured floor. The regression showed that costs were homogeneous (i.e., did not change with lameness prevalence; marginal cost equals average cost). A lame cow and a DD-affected cow cost €307.50 ± 8.40 (SD) and €391.80 ± 10.0 per year on average, respectively. The results also showed a cost of €12.10 ± 0.36 per week-cow lameness. The present estimation is the first to account for interactions between etiologies and for the complex DD dynamics with all the M-stage transitions, bringing a high level of accuracy to the results.

German Farmers' Awareness of Lameness in Their Dairy Herds

Lameness is one of the most challenging problems in the dairy industry. Control is impeded because farmers often underestimate the number of lame cows. The objectives of this study were to assess German farmers' awareness of lameness in their herds and to determine the associations between farmers' awareness and their management practices, farm characteristics as well as with farmers' education, personality traits and attitudes. As a part of a large cross-sectional study, veterinarians visited farms in three structurally different regions of Germany: north (n = 253), east (n = 252), and south (n = 260). The cows (n = 84,998) were scored for locomotion and farmers were asked to estimate the number of cows that were lame or did not walk soundly. The ratio of farmers' estimated prevalence and the veterinarians' observed prevalence (Farmer's Detection Index; FDI) was calculated. The median lameness prevalence assessed by the veterinarians was 23.1, 39.1, and 23.2%, and the median prevalence of lame cows estimated by the farmers was 9.5, 9.5, and 7.1% in the north, east, and south, respectively. On average, farmers were conscious of only 45.3% (north), 24.0% (east), and 30.0% (south) of their lame cows. Farmers managing their herds according to organic principles had a higher FDI than farmers who managed their herds conventionally. Surprisingly, no significant associations between FDI and factors concerning claw health management could be detected. Therefore, increased awareness did not seem to be necessarily linked to improved management. Moreover, the FDI was not significantly associated with farmers' education or herd size. In the south, more extraverted farmers had a lower FDI. Those farmers who totally agreed with the statement, “I am satisfied with my herd's health,” had a lower FDI than farmers who disagreed or were undecided. Moreover, farmers who disagreed or were undecided with the statement, “It affects me to see a cow in pain” had a higher FDI than those farmers who agreed to the statement. The results indicate that poor awareness of lameness was linked to the farmers' attitude and personality. Therefore, new approaches concerning the consultation regarding lameness control, such as the use of Motivational Interviewing, might be useful in the future.

Dairy farmer, hoof trimmer, and veterinarian perceptions of barriers and roles in lameness management

Lameness is a leading animal welfare concern in the dairy industry. Multiple stakeholders are involved in lameness management on a dairy farm, including farmers, hoof trimmers, and veterinarians. This study sought to explore perceptions of lameness, perceptions of roles in lameness management, and barriers to improved lameness management in these groups. Fourteen homogeneous focus groups were held in Minnesota, Wisconsin, and New York from April 2017 to March 2020; 5 with farmers (n = 31), 4 with hoof trimmers (n = 32), and 5 with veterinarians (n = 25). The 1-h facilitated discussions were audio-recorded, transcribed verbatim, and common themes identified through thematic analysis. Lameness was perceived by participants as a complex health problem and one in which the connections between pathogenesis, facilities, and management were not always well understood or easy to change. The complexity of the problem encompassed the lack of agreement on a definition of lameness, normalization to its signs, and the interconnectedness of lameness with other health and management issues. These issues appeared to contribute to resignation by participants that lameness was inevitable. Despite shared concerns about lameness among these groups, respondents reported a lack of communication, especially between hoof trimmers and veterinarians. Participants also voiced a desire to work together more productively, with hoof trimmers and veterinarians valuing the ability to deliver a consistent message to farmers. These findings suggest a need for increased efforts to facilitate collaboration between farmers, hoof trimmers, and veterinarians to improve lameness management on dairy farms.