Effects of retinoic acid and hydrogen peroxide on sterol regulatory element-binding protein-1a activation during adipogenic differentiation of 3T3-L1 cells

Descriptive evaluation of a camera-based dairy cattle lameness detection technology

Lameness in dairy cattle is a clinical sign of impaired locomotion, mainly caused by painful foot lesions, compromising the US dairy industry's economic, environmental, and social sustainability goals. Combining technology and on farm data may be a more precise and less labor-intensive lameness detection tool, particularly for early detection. The objective of this observational study was to describe the association between average weekly autonomous camera-based (AUTO) locomotion scores and hoof trimming (HT) data. The AUTO data were collected from 3 farms from April 2022 to March 2023. Historical farm HT data were collected from March 2016 to March 2023 and used to determine cow lesion history and date of HT event. The HT events were categorized as a regular HT (TRIM; n = 2290) or a HT with a lesion recorded (LESION; n = 670). Events with LESION were sub-categorized based on lesion category: digital dermatitis (DD; n = 276), sole ulcer (SU; n = 79), white line disease (WLD; n = 141), and other (n = 174). The data also contained the leg of the LESION, classified as front left (FL; n = 54), front right (FR; n = 146), rear left (RL; n = 281), or rear right (RR; n = 183) leg with 6 events missing the leg. Cows' HT histories were classified as follows: cows with no previous recorded instance of any lesion were classified as TRIM0 (n = 1554). The first instance of any hoof lesion was classified as LESION1 (n = 238). This classification was retained until a subsequent TRIM occurred - recorded as TRIM1 (n = 632). The next unique instance of any lesion following a TRIM1 was classified as LESION2 (n = 86). Any LESION events occurring after LESION1 or LESION2 without a subsequent TRIM were considered a hoof lesion recurrence and classified as LESIONRE1 (n = 164) and LESIONRE2 (n = 22), respectively. TRIM events after LESION2 or LESION2RE (n = 104) or LESION events after LESIONRE1 or LESIONRE2 were classified as LESION_OTHER (n = 160). The AUTO scores from -28 to -1 days prior to the HT event were summarized into weekly scores and included if cows had at least 1 observation per week in the 4 weeks before the event. For all weeks, LESION cows had a higher median AUTO score than TRIM cows. Cows with TRIM0 had the lowest and most consistent median weekly score compared to LESION and other TRIM classifications. Before HT cows with TRIM0 and TRIM1, both had median score increases of 1 across the 4 weeks, while the LESION categories had an increase of 4 to 8. Scores increased with each subsequent LESION event compared to the previous LESION event. Cows with SU lesions had the highest median score across the 4 weeks, WLD had the largest score increase, and DD had the lowest median score and score increase. When grouping a LESION event by leg the hoof lesion was found on, the AUTO scores for four groups displayed comparable median values. Due to the difference between TRIM and LESION events, this technology shows potential for the early detection of hoof lesions.

Multilocus sequence typing of pathogenic treponemes isolated from contagious ovine digital dermatitis stage five lesions: Implications for disease transmission dynamics

Contagious ovine digital dermatitis (CODD) causes a severe, infectious foot disease and lameness of sheep, is common within the UK and is now also emerging in other countries. As well as causing severe animal welfare issues, huge economic losses emerge from the disease due to weight loss/lack of weight gain, and veterinary treatments. CODD lesion progress is measured, with a scoring system from 1 (early lesions) to 5 (healed). Here, using samples from an experimental flock infected by natural means, samples were taken from CODD stage 5 lesions, post treatment, and subjected to bacterial isolation and MLST using previously published methods. Sequences were compared to others from the same flock, and those from previous studies. All CODD 5 lesions produced viable Treponema spp. bacteria. High levels of variation of bacteria were seen, with 12 sequence types (STs) for T. medium phylogroup (11 new), 15 STs for T. phagedenis phylogroup (9 new) and six T. pedis STs, of which two were new. This study shows that CODD stage 5 lesions still contain viable bacteria, representing all three known pathogenic Treponema spp. phylogroups, and these may thus play a role in disease transmission and epidemiology despite appearing healed after treatment. The high level CODD treponeme variability within an infected flock where sheep were bought from different sources, as might occur in common agricultural practice, may suggest reasons as to why the bacterial disease is difficult to treat, control and eradicate, and adds further complexity to the polybacterial pathogenesis of these lesions.

Association between hoof trimming frequency in primiparous cows and hoof health and survival in second lactation

Lameness, mostly resulting from claw lesions, causes major welfare problems in the dairy industry. One way to prevent claw lesions is hoof trimming, but the overall effect and the optimal hoof trimming frequency are unknown. In a retrospective cohort study, we investigated the association between hoof trimming frequency in primiparous cows and hoof health and culling in second lactation. We based our analysis on breed, calving and culling data in the period 2015-2018 for 30,613 primiparous cows in 202 Swedish dairy herds. Of the cows enrolled, 20% were not hoof-trimmed, 30% were trimmed once, 34% were trimmed twice, 13% were trimmed 3 times, and 2% were trimmed ≥ 4 times. We used multivariable mixed-effect logistic and multivariable multinomial logistic regression models to investigate the association between trimming frequency and 2 outcomes: hoof lesions at first trimming occasion within 90 d from second calving and culling in second lactation within 300 d after second calving. In general, cows trimmed 2 or 3 times during first lactation were at lower odds of having claw lesions compared with cows that were not trimmed (Odds Ratio (OR) = 0.66, 95% CI = 0.62-0.71 and 0.60, 95% CI = 0.55-0.66, respectively) or cows trimmed once (OR = 0.80, 95% CI = 0.75-0.85 and OR = 0.72, 95% CI = 0.66-0.79, respectively), and this beneficial effect was observed for most types of claw lesions. Moreover, cows trimmed 2, 3, or ≥ 4 times were at lower odds of being culled compared with cows that were not trimmed (OR = 0.71, 95% CI = 0.65-0.77, 0.68, 95% CI = 0.61-0.76 and 0.70, 95% CI = 0.54-0.90, respectively) or trimmed once (OR = 0.77, 95% CI = 0.71-0.83, OR = 0.74, 95% CI = 0.66-0.82 and OR = 0.75, 95% CI = 0.59-0.97, respectively). In particular, 2 trimmings, compared with 1 or no trimming, lowered the relative risk-ratio of dying or being euthanized on-farm, or being culled due to claw and leg disorders. More than 1 hoof trimming in first lactation also reduced the relative-risk ratio of being culled for other reasons. In conclusion, 2 or 3 hoof trimmings during first lactation were generally beneficial for hoof health in early second lactation and survival in second lactation. These findings can help improve animal welfare and production by reducing claw lesions, and thereby lameness among dairy cows, which would increase the longevity of dairy cows and the sustainability of the dairy industry.

Prevalence of Lameness in Dairy Cows and Associated Risk Factors at Hawassa Town Dairy Farms, Ethiopia

Lameness is one of the greatest constraints on the productivity, health, and welfare of dairy cattle. A cross-sectional study was carried out from March 2021 to September 2021 in Hawassa town with the aim of assessing the prevalence and identifying the associated risk factors of lameness in dairy farms. The study was conducted on 440 animals belonging to 19 randomly selected intensive dairy farms. Data regarding lameness and its possible risk factors were collected both at animal and farm level using a questionnaire. The results showed that the overall prevalence of lameness was 10.2% (n = 45/440). The association of lameness prevalence with various risk factors including milking status, exercise, age, parity, milk yield, and lactation stage was statistically tested using logistic regression model. There was a significant variation in the prevalence of lameness (P < 0.05) between cattle with different milking status, age, parity, milk yield, and stage of lactation by the univariable analysis result. According to the multivariable analysis, only milk yield and lactation stage were statistically associated with the occurrence of lameness. Milking animals (8%) had higher prevalence of lameness than nonmilking (2.2%). The occurrence of lameness increased with milk yield. The highest prevalence of lameness was recorded in the early stage of lactation. Lameness was more frequent in hind limbs (6.6%) than in forelimbs (3.6%). The main causes of lameness observed in this study were both claw overgrowth 10 (2.3%), unequal claw size 10 (2.3%), solar ulcer 8 (1.8%), interdigital necrobacillosis 2 (0.5%), interdigital hyperplasia 2 (0.5%), and digital dermatitis 1 (0.2%). There was no means of early lameness diagnosis in 94.7% of farms. Lameness was found to be an important disease in dairy cows at Hawassa town. Prevention and early diagnosis leading to prompt treatment of lameness in cows should be part of dairy farm management practice.

An abattoir study of the prevalence of foot lesions and claw measurements in water buffalo in Egypt

BACKGROUND

Lameness has been associated with compromised animal welfare and reduced productivity in dairy cattle herds worldwide. However, little is known about the prevalence of claw lesions in the dairy buffalo population in Egypt. Furthermore, the optimum measurements for claw trimming in buffalo are unknown. A cross-sectional cadaver study was conducted where 135 pair buffalo hind feet were collected from 4 slaughterhouses and examined for the presence of claw lesions. The proportion and associated 95% confidence interval (CI) of each type of lesion were calculated. A separate set of healthy claws (n = 26) underwent ultrasonography (US) and computed tomography (CT). The agreement between US and CT measurements was assessed using Passing-Bablok regression and intraclass correlation coefficient. The CT measurements were used to calculate trimming recommendations.

RESULTS

At least one lesion was identified in 242 claws (89.6%, 95% CI = 85.4-93.0). In healthy claws, poor to moderate agreement was identified between US and CT measurements which could be due a sample size of the study. The average ± standard deviation (SD) minimum recommended external wall length of the lateral and medial claws in heifers was 7.1 ± 0.36 cm and 7.5 ± 0.35 cm, respectively. The average ± SD minimum recommended external wall length in buffaloes over five years of age was 8.2 ± 0.27 cm and 8.4 ± 0.39 cm for the lateral and medial claws, respectively.

CONCLUSIONS

The study found a high prevalence of claw lesions in buffalo in Egypt, the clinical significance of which requires further elucidation. Recommended measurements will help guide claw trimming in buffalo to minimise lesions.

Exploring farmer and advisor lameness management behaviors using the COM-B model of behavior change

Introduction

This paper applies the COM-B framework to farmer and farm advisor understandings and responses to lameness in sheep, beef, and dairy systems. It reflects on how farmers' and advisors' capability, opportunity, and motivation (COM-B) influence lameness management practices in these farming systems, and considers the interaction between these three factors, and stakeholders' behavior.

Methods

Interviews with 29 farmers and 21 farm advisors in the north of England were conducted. Thematic analysis was undertaken with results categorized in relation to the COM-B framework focusing on barriers and enablers of lameness management. Use of the COM-B model provides a useful means of understanding the underlying behavioral mechanisms that contribute toward the persistence of lameness. This includes the complexities and interactions which hamper implementation of lameness management best practice.

Results and discussion

The findings highlight three key areas to address with interventions to improve lameness management on farm: (1) removing physical and social barriers for lameness management; (2) improving psychological capability and motivation for lameness management; and (3) facilitating relationships and developing communication between farmers and advisors. In particular, the value of exploring both farmer and advisor perspectives on behavior in the animal health context is demonstrated. Future interventions should look to target these three areas to overcome barriers and focus on factors that enable positive lameness practices to occur.

Prevalence of lameness on pasture-based New Zealand dairy farms: An observational study

To understand the current impact of lameness on a system, it is important to define lameness prevalence across a range of dairy farms in that system. Prevalence estimates from dairy systems where cows are permanently managed at pasture are uncommon, although the limited data suggest that they have a lower lameness prevalence than housed cattle. One hundred and 20 farms from eight of the major dairying regions of New Zealand were randomly enrolled into a cross-sectional lameness prevalence study. On each of the farms, trained observers lameness scored cattle on two occasions, between October-December (spring, coinciding with peak lactation for most farms) and between January-March (summer, late lactation for most farms). At each visit, all lactating animals were scored using a four-point 0-3 scoring system, and included animals that had previously been identified as lame by the farmer. Animals with a lameness score (LS) ≥2 were defined as lame. Mixed logistic regression models assessed the interaction between region and season and island and season, respectively, and differences between the lameness prevalence within farm across the two seasons reported descriptively. A total of 116,317 locomotion scores over two events were conducted across the 120 farms. At the spring scoring event, 2128/60,007 (3.5 %) cows had a LS ≥2 and 1868/56,310 (3.3 %) cows had a LS ≥ 2 at the summer scoring event. At the farm level, across both scoring events, median lameness prevalence was 2.8 (interquartile range 1.5 - 4.5) %, with a range of 0.0-17.0 %. The median farm-level prevalence of LS = 3 was 0.5 % with a range of 0-4.6 %. The effect of timing of scoring was modified by region (p < 0.001), and island (p = 0.006) and at the individual farm level, differences between spring and summer farm level lameness prevalence were generally small (interquartile range: -1.8 to 1.0 %) but potentially large on individual farms (range from -12.3 % to 7.6 %). The median farm-level lameness prevalence estimate of 2.8 % across a random representative sample of New Zealand dairy farms give confidence that the overall prevalence of cattle lameness on New Zealand dairy farms is low. This adds to the growing evidence that pasture is a good management system with respect to hoof health. The evidence of strong seasonality of lameness was lacking. Instead of using lameness scoring to identify farms with large lameness problems, lameness scoring should be encouraged to farmers as a tool to improve the identification of lame animals.

Lameness recovery rates following treatment of dairy cattle with claw horn lameness in the Waikato region of New Zealand

AIMS

To describe the time in days for lame dairy cows to recover after diagnosis and treatment of claw horn lameness, and to investigate whether cure rates differed between farms.

METHODS

Five dairy farms in the Waikato region were conveniently enrolled into a descriptive epidemiological study. Three of these farms had dairy cattle enrolled over two consecutive seasons, while two farms enrolled for one year. Lame cattle diagnosed by the farmers were enrolled into the study if they had a lameness score (LS ≥ 2 on a 0-3 scale) and claw horn lesions. All enrolled animals were treated by a single veterinarian following a consistent methodology, and subsequently assessed for LS at a median frequency of 4 days from enrolment until they were sound (LS = 0). The times (days) taken for animals to become sound and non-lame (LS < 2) were reported for all animals, and Kaplan-Meier survival curves used to present the results. A Cox-proportional hazard model was used to assess if the hazard of soundness was associated with farm, age, breed, lesion, number of limbs involved, and LS at enrolment.

RESULTS

A total of 241 lame cattle with claw horn lesions were enrolled across the five farms. White line disease was the predominant pain-causing lesion in 225 (93%) animals, and blocks were applied to 205 (85%) of enrolled animals. The overall median days from enrolment to becoming sound was 18 (95% CI = 14-21) days, and 7 (95% CI = 7-8) days to become non-lame. A difference in the hazards of lameness cure between farms was identified (p = 0.007), with median days to lameness cure between farms ranging from 11 to 21 days. No associations were identified between age, breed, limb, or LS at enrolment on the lameness cure rates.

CONCLUSIONS

Treatment of claw horn lameness following industry-standard guidelines in dairy cattle on five New Zealand dairy farms resulted in rapid cure, although cure rates differed between farms.

CLINICAL RELEVANCE

Following industry best-practice lameness treatment guidelines, including frequent use of blocks, can result in rapid lameness cure rates in New Zealand dairy cows. This study also suggests that management of lame cattle on pasture can positively benefit their welfare and recovery times. The reported cure rates provide veterinarians with benchmarks on the length of time after which a lame animal should be re-examined, and in the investigation of poor treatment response rates at the herd level.

A cross-sectional study of the prevalence of lameness and digital dermatitis in dairy cattle herds in Egypt

BACKGROUND

Lameness is a significant problem for the dairy industry worldwide. No previous studies have evaluated the prevalence of lameness or digital dermatitis (DD) in dairy cattle herds in Egypt. A total of 16,098 dairy cows from 55 dairy herds in 11 Egyptian governorates underwent visual locomotion scoring using a 4-point scoring system. Cows that had a lameness score ≥ 2 were considered clinically lame. Following manure removal with water and using a flashlight, the cows' hind feet were examined in the milking parlour to identify DD lesions and classify with M-score. Furthermore, each cow was assigned a hock score (a 3-point scale) and a hygiene score (a 4-point scale). The cow-, within-and between-herd prevalence of lameness and DD and associated 95% confidence intervals (CI) were calculated. The prevalence of hock lesions and poor cow hygiene was also calculated.

RESULTS

Of the examined cows, 6,883 were found to be clinically lame (42.8%, 95% CI = 42.0-43.5%). The average within-herd prevalence of lameness was 43.1% (95% CI = 35.9-50.3%). None of the dairy herds recruited into the study were found to be free from clinical lameness. The average within-herd prevalence of DD was 6.4% (95% CI = 4.9-8.0%). The herd-level prevalence of DD was 92.7% (95% CI = 85.9-99.6%). Active DD lesions (M1, M2, M4.1) were identified in 464 cows (2.9%) while inactive lesions (M3, M4) were identified in 559 cows (3.5%). The within-herd prevalence of hock lesions (score 2 or 3) was 12.6% (95% CI = 4.03-21.1%) while a severe hock lesion had within-herd prevalence of 0.31% (95% CI = 0.12-0.51%). Cow-level prevalence of hock lesions was 6.2% (n = 847, 95% CI = 5.8-6.2%). The majority of examined cows had a hygiene score of 4 (n = 10,814, prevalence = 70.3%, 95% CI = 69.5-71%).

CONCLUSIONS

The prevalence of lameness was higher than prevalence estimates reported for other countries which could be due to differing management and/or environmental factors. DD was identified at lower prevalence in most herds but with high herd-level prevalence. Poor cow hygiene was notable in most herds. Measures to reduce the prevalence of lameness and to improve cow hygiene in dairy cattle herds in Egypt are therefore needed.

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.

Drivers and indicators of dairy animal welfare in large-scale dairies (review)

While animal welfare concerns are rising globally, this has not been the case with lower- and middle-income economies in Africa and Asia such as Zimbabwe. These developing countries have their own problems which are not reported in developed countries, such as the harsh economic environment, limited technologies and different political and food security priorities. These factors limit focusing on animal welfare. Meanwhile, studies on animal welfare in these countries have been limited. The task of determining animal welfare is a very complex and can sometimes be very subjective since there is no gold standard protocol to be used in many developing countries. This paper reviews the main factors that are used to assess dairy animal welfare at a farm situation. The factors were categorised and generally discussed as drivers and indicators of dairy animal welfare. Key indicators reviewed in this study include but are not limited to production performance indicators, body condition scores, cleanliness scores, presence of clinical disease signs and physiological and behavioural indicators. Dairy animal welfare drivers discussed in this paper include but not limited to the general design of dairy cattle housing, presence of foot bath and shading facilities, presence and use of maternity paddocks, state of feeder and water troughs.

Association between Milk Electrical Conductivity Biomarkers with Lameness in Dairy Cows

Early identification of lameness at all phases of lactation improves milk yield and reduces the incidence of mastitis in the herd. According to the literature we hypothesized that there are associations of electrical conductivity variables of milk flow with lameness in dairy cows. The aim of this study was to determine if blood cortisol and electrical conductivity in the milk flow phases correlate with each other and whether they are related to cow lameness. On one farm, out of 1500 cows, 64 cows with signs of lameness and 56 healthy cows were selected with an average of 2.8 lactations and 60 days in the postpartum period. A local veterinarian who specializes in hoof care treatments identified and scored lameness. During evening milking, the milk flow of all 120 cows was measured using electronic milk flow meters (Lactocorder®, WMB AG, Balgache, Switzerland). Before each milking, two electronic mobile milk flow meters (Lactocorders) were mounted between the milking apparatus and the milking tube to take measurements. We found that the average cortisol concentration in the blood of the studied cows was significantly correlated with the laminitis score. Results of this study indicate that the number of non-lame cows with a milk electrical conductivity level of <6 mS/cm even reached 90.8−92.3% of animals. Milk electrical conductivity indicators ≥ 6 mS/cm were determined in 17.8−29.0% more animals in the group of lame cows compared to the group of non-lame cows. According to our study, we detected that blood cortisol concentration had the strongest positive correlation with milk electrical conductivity indicators. Cows with a greater lameness score had a higher cortisol content and milk conductivity.

Metabolic alterations in dairy cattle with lameness revealed by untargeted metabolomics of dried milk spots using direct infusion-tandem mass spectrometry and the triangulation of multiple machine learning models

Lameness is a major challenge in the dairy cattle industry in terms of animal welfare and economic implications. Better understanding of metabolic alteration associated with lameness could lead to early diagnosis and effective treatment, there-fore reducing its prevalence. To determine whether metabolic signatures associated with lameness could be discovered with untargeted metabolomics, we developed a novel workflow using direct infusion-tandem mass spectrometry to rapidly analyse (2 min per sample) dried milk spots (DMS) that were stored on commercially available Whatman® FTA® DMPK cards for a prolonged period (8 and 16 days). An orthogonal partial least squares-discriminant analysis (OPLS-DA) method validated by triangulation of multiple machine learning (ML) models and stability selection was employed to reliably identify important discriminative metabolites. With this approach, we were able to differentiate between lame and healthy cows based on a set of lipid molecules and several small metabolites. Among the discriminative molecules, we identified phosphatidylglycerol (PG 35:4) as the strongest and most sensitive lameness indicator based on stability selection. Overall, this untargeted metabolomics workflow is found to be a fast, robust, and discriminating method for determining lameness in DMS samples. The DMS cards can be potentially used as a convenient and cost-effective sample matrix for larger scale research and future routine screening for lameness.

Hoof lesions in partly housed pasture-based dairy cows

Lameness is a symptom of a painful disorder affecting the limbs, which impacts dairy cow welfare and productivity. Lameness is primarily caused by hoof lesions. The prevalence of different lesion types can differ depending on environmental conditions and farm management practices. The aims of this observational study were to establish the cow-level and herd-level lesion prevalence during both housing and grazing periods in a partly housed, pasture-based system, establish the prevalence of lesions always associated with pain ("alarm" lesion), identify the lesions associated with a higher lameness score, determine relationships between lesions, and identify risk factors for digital dermatitis. On 98 farms during the grazing period and on 74 of the same farms during the housing period, every cow was lameness scored (0-3 lameness scoring scale), and the hind hooves of lame cows (score 2 and 3) were examined (maximum 20 cows per visit) and the prevalence of each lesion type recorded. To gather data on potential predictors for the risk factor analysis, a questionnaire with the farmer was conducted on lameness management practices and infrastructure measurements were taken at each visit. Cow-level data were also collected (e.g., parity, breed, milk yield, and so on). Noninfectious lesions were found to be more prevalent than infectious lesions in this system type. The most prevalent lesion types during both grazing and housing periods were white line separation, sole hemorrhages and overgrown claws; all remaining lesions had a cow-level prevalence of less than 15%. The cow-level prevalence of alarm lesions was 19% during the grazing period and 25% during the housing period; the most prevalent alarm lesion was sole ulcers during both periods. We found significantly more foreign bodies within the hoof sole (grazing = 14%, housing = 7%) and overgrown claws (grazing = 71%, housing = 55%) during the grazing period compared with the housing period. Cows with foul of the foot, sole ulcer, white line abscess, toe necrosis or an amputated claw had higher odds of being more severely lame, compared with mildly lame. The strongest correlation between lesions were between toe necrosis and digital dermatitis (r = 0.40), overgrown claws and corkscrew claws (r = 0.33), and interdigital hyperplasia and digital dermatitis (r = 0.31) at herd level. At the cow level, the strongest correlation was between overgrown claws and corkscrew claws (r = 0.27), and digital dermatitis and heel erosion (r = 0.22). The farmers' perception of the presence of digital dermatitis (and lameness) was significantly correlated with the actual presence of digital dermatitis recorded. Additional risk factors for the presence of digital dermatitis were cow track and verge width near the collecting yard, and stone presence on the cow tracks. Results from this study help further our understanding of the causes of lameness in partly housed, pasture-based dairy cows, and can be used to guide prevention and treatment protocols.

Comparison of Low- and High-Cost Infrared Thermal Imaging Devices for the Detection of Lameness in Dairy Cattle

Simple Summary

Lameness has high economic and welfare cost to the U.K. dairy industry; accurate and early detection of lameness minimises this cost. Thermal imaging devices can be used as a method of detecting lameness; however, these devices are typically high-cost and fragile, limiting their usefulness in a farm setting. This study looked at the effectiveness of low-cost thermal imaging devices when used as lameness detection aids, by comparing one to a research-specification thermal imaging device. Thermal images were taken of cattle feet, and each cow was assessed for lameness. Both devices tested were able to determine whether the cattle were lame; however, the research-specification device performed marginally better at this function. This minimal difference in effectiveness between these devices suggests that low-cost thermal imaging devices could be used as a lameness detection aid; increased use of these devices by farmers may increase lameness detection rates and benefit animal welfare.

Abstract

Lameness has a high economic cost to the U.K. dairy industry; accurate and early detection of lameness minimises this cost. Infrared thermal imaging (IRT) devices have shown promising results for use as a lameness detection aid in cattle when used in research settings; these devices are typically high-cost, limiting their adoption. This study analysed the effectiveness of low-cost IRT devices (LCDs) as lameness detection aids, by comparing both maximum environmentally adjusted temperature values and hindfeet temperature difference collected by an LCD to the mobility score of the cow; this test was repeated for data collected by a research-specification device. Data collection occurred during routine milking of 83 cattle; each cow’s mobility was scored afterwards. Significant differences were found between lame and sound cows with the LCD, upon analysis of both methods. There was no significant difference between the data captured by differing devices. The maximum sensitivity and specificity values for the LCD were calculated as 66.95 and 64.53, respectively, compared with 70.34 and 70.94, respectively, for the research-specification device; optimum threshold values for these were equivalent for both devices, suggesting IRT lameness identification is not device-dependent. It was concluded that a minimal difference in effectiveness between tested devices suggests that LCDs could be used as a lameness detection aid; consequently, there is potential for widespread adoption as on-farm detection aids.

Lameness prevalence and management practices on Irish pasture-based dairy farms

Background

Lameness is a painful disease, which negatively impacts dairy cow production and welfare. The aim of this observational study was to determine herd lameness prevalence, describe current lameness management practices and identify the presence of established risk factors for lameness on Irish pasture-based dairy farms. Farms were visited once during grazing (99 farms) and again during housing (85 farms). Lameness scoring was carried out at each visit (AHDB 0–3 scale); cows were classified as lame if they scored two or three. Farm management practices and infrastructure characteristics were evaluated via farmer questionnaires and direct measurements of farm infrastructure.

Results

Median herd-level lameness prevalence was 7.9% (interquartile range = 5.6 – 13.0) during grazing and 9.1% (interquartile range = 4.9 – 12.0) during housing; 10.9% of cows were lame at a single visit and 3.5% were lame at both visits (chronically lame or had a repeat episode of lameness). Fifty-seven percent of farmers were not familiar with lameness scoring and only one farm carried out lameness scoring. Only 22% of farmers kept records of lame cows detected, and 15% had a lameness herd health plan. Twenty-eight percent of farmers waited more than 48 h to treat a lame cow, and 21% waited for more than one cow to be identified as lame before treating. Six percent of farmers carried out routine trimming and 31% regularly footbathed (> 12 times per year). Twelve percent put severely lame cows in a closer paddock and 8% stated that they used pain relief to treat severely lame cows. Over 50% of farms had at least one cow track measurement that was classified as rough or very rough, and cow tracks were commonly narrow for the herd size. On 6% of farms, all cubicle beds were bare concrete (no matting or bedding) and on a further 6% of farms, there was a combination of cubicles with and without matting or bedding. On 56% of farms, all pens contained less than 1.1 cubicles per cow and on 28% of farms, a proportion of pens contained less than 1.1 cubicles per cow.

Conclusions

Overall, this study identified infrastructure and management practices which could be improved upon. The comparatively low lameness prevalence demonstrated, compared to fully housed systems, also highlights the benefits of a pasture-based system for animal welfare; however, there remains scope for improvement.

Estimating the burden of multiple endemic diseases and health conditions using Bayes’ Theorem: A conditional probability model applied to UK dairy cattle

The Global Burden of Animal Diseases (GBADs) is an international collaboration aiming, in part, to measure and improve societal outcomes from livestock. One GBADs objective is to estimate the economic impact of endemic diseases in livestock. However, if individual disease impact estimates are linearly aggregated without consideration for associations among diseases, there is the potential to double count impacts, overestimating the total burden. Accordingly, the authors propose a method to adjust an array of individual disease impact estimates so that they may be aggregated without overlap. Using Bayes’ Theorem, conditional probabilities were derived from inter-disease odds ratios in the literature. These conditional probabilities were used to calculate the excess probability of disease among animals with associated conditions, or the probability of disease overlap given the odds of coinfection, which were then used to adjust disease impact estimates so that they may be aggregated. The aggregate impacts, or the yield, fertility, and mortality gaps due to disease, were then attributed and valued, generating disease-specific losses. The approach was illustrated using an example dairy cattle system with input values and supporting parameters from the UK, with 13 diseases and health conditions endemic to UK dairy cattle: cystic ovary, disease caused by gastrointestinal nematodes, displaced abomasum, dystocia, fasciolosis, lameness, mastitis, metritis, milk fever, neosporosis, paratuberculosis, retained placenta, and subclinical ketosis. The diseases and conditions modelled resulted in total adjusted losses of £ 404/cow/year, equivalent to herd-level losses of £ 60,000/year. Unadjusted aggregation methods suggested losses 14–61% greater. Although lameness was identified as the costliest condition (28% of total losses), variations in the prevalence of fasciolosis, neosporosis, and paratuberculosis (only a combined 22% of total losses) were nearly as impactful individually as variations in the prevalence of lameness. The results suggest that from a disease control policy perspective, the costliness of a disease may not always be the best indicator of the investment its control warrants; the costliness rankings varied across approaches and total losses were found to be surprisingly sensitive to variations in the prevalence of relatively uncostly diseases. This approach allows for disease impact estimates to be aggregated without double counting. It can be applied to any livestock system in any region with any set of endemic diseases, and can be updated as new prevalence, impact, and disease association data become available. This approach also provides researchers and policymakers an alternative tool to rank prevention priorities.

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Three approaches to impact aggregation for multiple endemic diseases explored.

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Flexible method proposed to avoid double counting impacts within a livestock system.

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Illustrated using 13 endemic diseases and health conditions in UK dairy cattle.

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Provides an alternative perspective on ranking disease prevention priorities.

Association between a genetic index for lameness resistance and the incidence of claw horn lesions in Holstein cows

BACKGROUND

This study aimed to determine the association between the lameness advantage genetic index and four outcomes: sole haemorrhage (SH), sole ulcers (SU), white line lesions (WL), and lameness during mobility scoring.

METHODS

We enrolled 2352 Holstein cows from four predominantly housed dairy herds in the UK. Cows were mobility scored and foot lesions recorded at four time points from before calving to late lactation. Cows were genotyped and genetic indexes were assigned to each cow following national genetic evaluations. Lameness records and genetic indexes were matched for 2107 cows. Four separate multivariable logistic regression models, which included farm and parity as covariables, were used to quantify the association between the lameness advantage index and whether animals were affected by SH, SU, WL, or lameness.

RESULTS

The odds ratios (95% confidence intervals) for one-point increases in the lameness advantage index were 0.79 (0.72-0.86), 0.68 (0.59-0.78), 0.94 (0.84-1.04), and 0.82 (0.74-0.91) for SH, SU, WL, and lameness, respectively. The same trends were present when the sire's lameness advantage index was evaluated in place of the animal's own, although the strength of this association was generally weaker.

CONCLUSION

The lameness advantage index is associated with SH, SU, and lameness, therefore selection on the lameness advantage index could be considered in herds aiming to reduce lameness. Where genomic testing of heifers is not conducted, sire lameness advantage index may still be effective to reduce SH and SU incidence.

Lameness in Dairy Cow Herds: Disease Aetiology, Prevention and Management

As livestock production systems have changed to intensive commercial structures to meet the increasing demand for animal-based products, there has been an increase in food production diseases, subsequently resulting in animal welfare issues. After mastitis and infertility, lameness is one of the three major issues affecting dairy cattle globally, resulting in reduced productivity, economic losses, and animal welfare problems. Lameness is associated with reduced milk yield, lack of weight gain, poor fertility, and frequently, animal culling. Environmental (temperature, humidity) and animal risk factors contribute to disease severity, making this multifaceted disease difficult to eradicate and control. As such, prevalence rates of lameness in dairy herds ranges from 17% to 35% globally. Clinical lameness is often treated with antibiotic therapy, which is undesirable in food-producing animals, as outlined in the One Health and the European Farm to Fork food sustainability goals. Lameness is not a single disease in dairy cows but is the manifestation a range of issues, making lameness control one of the greatest challenges in dairy farming. Lameness prevention, therefore, must be a key focus of farm management and sustainable food production. There is an urgent need to establish farm-level aetiology of disease, promote the recognition of lameness, and implement effective control measures to lower incidence and transmission of disease within herds.

Diagnosis of Bovine Digital Dermatitis: Exploring the Usefulness of Indirect ELISA

The precision by which animal diseases are diagnosed affects our ability to make informed decisions with regards to animal health management, from a clinical and economic perspective. Lameness is a major health condition in dairy cattle. The underlying causes of lameness include bovine digital dermatitis (BDD), which is reported as one of the main causes of infectious lameness in dairy cattle. Presently, the gold standard for BDD diagnosis in dairy cattle is visual inspection of lifted hooves-a labour intensive and subjective method. Research has suggested that Treponema spp. are the main pathogens associated with the establishment of BDD. We explored the potential of indirect enzyme-linked immunosorbent assay (ELISA) as a diagnostic serological tool in the identification of cows at different stages of BDD. Additionally, we evaluated the predictive power of this diagnostic tool on the future occurrence of BDD lesions. A total of 232 cows from three farms were used in the study. Serum samples and hoof health data were collected at three time points: ~ 30 days pre-calving, around calving, and approximately 30 days post-calving. The mean absorbance from the ELISA test was compared across different clinical presentations of BDD as assessed by visual inspection of the hooves according to the M-stage classification system. A transition model was developed to estimate the probability of lesion occurrence in time t + 1 based on the spectrophotometer (absorbance) reading in time t. The mean absorbance reading for both IgG1 and IgG2 anti-Treponema antibodies was associated with disease presence-apart from M4.1 lesions, animals with no lesions had a lower mean when compared to animals with lesions regardless of the score. Additionally, the mean absorbance reading of animals with active lesions was higher when compared to animals with no lesions. However, the anti-Treponema antibody assays failed to identify disease presence in a consistent manner. Moreover, indirect ELISA readings were not a predictor of the future occurrence of BDD lesions. In conclusion, although the levels anti-Treponema antibodies were associated with disease presence, the ELISA test failed to detect disease unequivocally and had no predictive value in the future occurrence of BDD lesions.

Cow- and herd-level risk factors for lameness in partly housed pasture-based dairy cows

Lameness in dairy cows is a major animal welfare concern and has substantial economic impact through reduced production and fertility. Previous risk factor analyses have focused on housed systems, rather than those where cows were grazed for the majority of the year and housed only for the winter period. Therefore, the aim of this observational study was to identify a robust set of cow-level and herd-level risk factors for lameness in a pasture-based system, based on predictors from the housing and grazing periods. Ninety-nine farms were visited during the grazing period (April 2019-September 2019), and 85 farms were revisited during the housing period (October 2019-February 2020). At each visit, all lactating cows were scored for lameness (0 = good mobility, 1 = imperfect mobility, 2 = impaired mobility, 3 = severely impaired mobility), and potential herd-level risk factors were recorded through questionnaires and infrastructure measurements. Routine cow-level management data were also collected. Important risk factors for lameness were derived though triangulation of results from elastic net regression, and from logistic regression model selection using modified Bayesian information criterion. Both selection methods were implemented using bootstrapping. This novel approach has not previously been used in a cow-level or herd-level risk factor analysis in dairy cows, to the authors' knowledge. The binary outcome variable was lameness status, whereby cows with a lameness score of 0 or 1 were classed as non-lame and cows with a score of 2 or 3 were classed as lame. Cow-level risk factors for increased lameness prevalence were age and genetic predicted transmitting ability for lameness. Herd-level risk factors included farm and herd size, stones in paddock gateways, slats on cow tracks near the collecting yard, a sharper turn at the parlor exit, presence of digital dermatitis on the farm, and the farmers' perception of whether lameness was a problem on the farm. This large-scale study identified the most important associations between risk factors and lameness, based on the entire year (grazing and housing periods), providing a focus for future randomized clinical trials.

Roles of vitamin A in the regulation of fatty acid synthesis

Dietary macronutrients and micronutrients play important roles in human health. On the other hand, the excessive energy derived from food is stored in the form of triacylglycerol. A variety of dietary and hormonal factors affect this process through the regulation of the activities and expression levels of those key player enzymes involved in fatty acid biosynthesis such as acetyl-CoA carboxylase, fatty acid synthase, fatty acid elongases, and desaturases. As a micronutrient, vitamin A is essential for the health of humans. Recently, vitamin A has been shown to play a role in the regulation of glucose and lipid metabolism. This review summarizes recent research progresses about the roles of vitamin A in fatty acid synthesis. It focuses on the effects of vitamin A on the activities and expression levels of mRNA and proteins of key enzymes for fatty acid synthesis in vitro and in vivo. It appears that vitamin A status and its signaling pathway regulate the expression levels of enzymes involved in fatty acid synthesis. Future research directions are also discussed.

MORBIDITY AND MORTALITY OF TAKIN (BUDORCAS TAXICOLOR) IN NORTH AMERICAN ZOOLOGICAL INSTITUTIONS FROM 1997 TO 2017

Takin (Budorcus taxicolor) are classified as "Vulnerable" on the International Union for the Conservation of Nature Red List. Thus, ex situ conservation efforts provide assurance populations for future survival of this species. The objective of this study was to identify common causes of morbidity and mortality in takin populations in human care. Twenty North American institutions that housed takin from 1997 to 2017 completed a survey requesting medical and husbandry data. Data were examined broadly, by sex and age groups. There were 206 morbidity events (male = 133; female = 73) submitted across 102 takin (male = 62; female = 40). The most common causes of morbidity were infectious or inflammatory diseases (50%; 104/206), degenerative diseases (22%; 46/206), and traumatic events (17%; 34/206). Necropsy reports were provided for 42 takin that died during the study period. The most common causes of mortality were infectious or inflammatory diseases (26%; 11/42), traumatic events (24%; 10/42), and degenerative disease (12%; 5/42). Sixty-two percent of infectious or inflammatory diseases causing morbidity were associated with endoparasites (64/104). Degenerative joint diseases more commonly affected males (78%; 36/46) as well as forelimbs (48%; 22/46) when compared to hindlimbs (30%; 14/46) and unspecified limbs (22%; 10/46). The prevalence of trauma as a cause of morbidity and mortality was higher in neonate and juvenile takin groups combined (morbidity = 19%; mortality = 50%) as compared to adult and senior takin groups combined (morbidity = 15%; mortality = 11%). Older takin were euthanatized more often (57%; 16/28) than younger takin (29%; 4/14). Correlations between husbandry and health were difficult as a result of the inherent limitations of the survey. These data will inform takin-holding zoologic institutions and contribute to the successful management of takin in human care.

A Retrospective Case Study into the Effect of Hoof Lesions on the Lying Behaviour of Holstein-Friesian in a Loose-Housed System

Simple Summary

Lameness is a substantial welfare and economic problem in production animals. It can alter indicators of welfare such as lying time. Lying down is very important for cows, and they are highly motivated to perform this behaviour for 12 h or more per day. Conversely, cows that lie down too much or are uncomfortable standing may miss an opportunity to feed or drink if there is competition from sound (non-lame) cows. This study monitored different lesions that cause lameness in cattle through the use of accelerometers. The lesions included sole ulcers, sole haemorrhage, white line disease, interdigital hyperplasia and phelgmon, and digital dermatitis. Leg-based activity monitors that track the cows’ lying behaviour and mobility were used. From these data, it was found that cows with lesions on the foot spent longer lying down than those with no lesions, and cows with lesions in the soft tissue spent less time lying down than those with foot lesions. Trimming the cows’ feet altered the lying times of the cows with foot lesions and returned them closer to those of cows with no lesions.

Abstract

The association between hoof lesions and lying behaviour was assessed on a Holstein–Friesian dairy farm in England. Twenty-nine cows were included in the study. Cows with claw horn disruption lesions (CHDL, n = 8), soft tissue lesions (STL, n = 6), and no lesions (NL, n = 15) were assessed. Data were collected on parity, days in milk (DIM), and mobility scores. Cows were trimmed and treated, and lesions were recorded by a professional foot trimmer. Lying behaviour was assessed before and after claw trimming. The milking herd (n = 96) prevalence of lameness was 32.3%. Mobility was scored using the Agriculture and Horticulture Development Board (AHDB) Mobility Scoring system. Mobility scores were significantly different across lesions groups (p = 0.022). CHDL cows had a mean mobility score of 2.0 ± 0.9 (mean ± SD), STL were scored 1.2 ± 1.3, and NL cows were 0.9 ± 0.7. CHDL were associated with longer lying times (15.00 ± 1.04 h/d; p = 0.0006) and shorter standing times (9.68 ± 2.38 h/d; p = 0.0351) compared with NL lying times (11.77 ± 1.67 h/d) and standing times (12.21 ± 1.67 h/d). STL cows spent significantly less time lying (11.30 ± 2.44; p = 0.0013) than CHDL but not NL cows. No significant differences were found with any of the other lying behaviours. After trimming, CHDL cows spent significantly less time lying down than before trimming (13.66 ± 0.98; p = 0.0125). Cows with NL spent significantly more time lying down (12.57 ± 1.90; p = 0.0398) and had a shorter minimum lying bout duration (0.17 ± 0.09; p = 0.0236) after trimming. In conclusion, lying behaviour in dairy cattle was impacted by type of hoof lesions and hoof trimming.

Resource, Collaborator, or Individual Cow? Applying Q Methodology to Investigate Austrian Farmers' Viewpoints on Motivational Aspects of Improving Animal Welfare

One keystone to successful welfare improvement endeavors is a respected cooperation between farmer and advisor (e.g., veterinarian), which requires a thorough understanding of what motivates farmer behavior. In this respect, Q methodology offers a promising approach in investigating individual motivational patterns and to discriminate between and describe typologies of farmers. In our study we explored, based on a sample of 34 Austrian dairy farmers, how 39 potentially motivating statements regarding the improvement of dairy cow health and welfare were assessed. We were able to identify and describe four different viewpoints, explaining 47% of total study variance. All four viewpoints have in common that pride in a healthy herd is motivating to work toward improved animal health and welfare to a certain extent, but meeting legal requirements is rather not. Viewpoint 1 acknowledges welfare for economic performance, ease of work and short working hours but does not make allowance for outside interference. Participants loading on Viewpoint 2 also show a focus on economic aspects but, keep close track of the animal welfare debate recognizing its potential to improve the public image of dairy farming. Even though they cautiously criticize an exploitative application of dairy farming, they do not want to be understood as role models. With regards to animal welfare, farmers sharing Viewpoint 3 perceive themselves as superior to and show little reluctance of comparison with mainstream farming. For them, the animal as sentient being itself owns some intrinsic value and it is necessary to strike a balance between economic and other, ethical considerations. Viewpoint 4 perceives cows as equal collaborators who deserve to be treated with respect and appreciation and is willing to accept certain economic losses in order to maintain high standards regarding animal health and welfare. Using Q methodology, we have been able to draw high resolution images of different farmer typologies, enabling advisors to tailor intervention strategies specifically addressing leverage points with a high chance of farmer compliance.

Factors Associated With Lameness in Tie Stall Housed Dairy Cows in South Germany

Lameness remains a major concern for animal welfare and productivity in modern dairy production. Even though a trend toward loose housing systems exists and the public expects livestock to be kept under conditions where freedom of movement and the expression of natural behavior are ensured, restrictive housing systems continue to be the predominant type of housing in some regions. Factors associated with lameness were evaluated by application of multiple logistic regression modeling on data of 1,006 dairy cows from 56 tie stall farms in Bavaria, South Germany. In this population, approximately every fourth cow was lame (24.44% of scored animals). The mean farm level prevalence of lameness was 23.28%. In total, 22 factors were analyzed regarding their association with lameness. A low Body Condition Score (BCS) (OR 1.54 [95%-CI 1.05-2.25]) as well as increasing parity (OR 1.41 [95%-CI 1.29-1.54]) entailed greater odds of lameness. Moreover, higher milk yield (OR 0.98 [95%-CI 0.96-1.00]) and organic farming (OR 0.48 [95%-0.25-0.92]) appeared to be protectively associated with lameness. Cows with hock injuries (OR 2.57 [95%-CI 1.41-4.67]) or with swellings of the ribs (OR 2.55 [95%-CI 1.53-4.23]) had higher odds of lameness. A similar association was observed for the contamination of the lower legs with distinct plaques of manure (OR 1.88 [95%-CI 1.14-3.10]). As a central aspect of tie stall housing, the length of the stalls was associated with lameness; with stalls of medium [(>158-171 cm) (OR 2.15 [95%-CI 1.29-3.58]) and short (≤158 cm) length (OR 4.07 [95%-CI 2.35-7.05]) increasing the odds compared with long stalls (>171 cm). These results can help both gaining knowledge on relevant factors associated with lameness as well as approaching the problem of dairy cow lameness in tie stall operations.

Profiling Detection and Classification of Lameness Methods in British Dairy Cattle Research: A Systematic Review and Meta-Analysis

Lameness is a serious concern in the dairy sector, reflecting its high incidence and impact on animal welfare and productivity. Research has provided figures on its frequency using different methodologies, making it difficult to compare results and hindering farm-level decision-making. The study's objectives were to determine the frequency levels of lameness in British dairy cattle through a meta-analysis approach, and to understand the chronological patterns of how lameness cases are detected and classified in scientific research. A systematic review was conducted using PRISMA-P guidelines for article selection. Random-effects models estimated the pooled frequency measure of lameness with heterogeneity managed through subgroup analysis and meta-regression. Sixty-eight papers were identified, 50 included prevalence and 36 incidence data. The pooled prevalence of lameness in British dairy cattle was estimated at 29.5% (95% CI 26.7-32.4%) whilst all-cause lameness incidence rate indicated 30.9 cases of lameness per 100 cow-years (95% CI 24.5-37.9). The pooled cause-specific lameness incidence rate per 100 cow-years was 66.1 (95% CI 24.1-128.8) for white line disease, 53.2 (95% CI 20.5-101.2) for sole ulcer, 53.6 (95% CI 19.2-105.34) for digital dermatitis, with 51.9 (95% CI 9.3-129.2) attributable to other lameness-related lesions. Heterogeneity levels remained high. Sixty-nine papers contributed to a chronological overview of lameness data source. Although the AHDB Dairy mobility scoring system (MSS) was launched in the UK in 2008 and adopted shortly after by the British Dairy sector as the standard tool for assessing lameness, other methods are used depending on the investigator. Automated lameness detection systems may offer a solution for the subjective nature of MSSs, yet it was utilized in one study only. Despite the recognition of under-reporting of lameness from farm records 22 (31.9%) studies used this data source. The diversity of lameness data collection methods and sources was a key finding. It limits the understanding of lameness burden and the refinement of policy making for lameness. Standardizing case definition and research methods would improve knowledge of and ability to manage lameness. Regardless of the measurement method lameness in British dairy cattle is high.

Grazing Cow Behavior's Association with Mild and Moderate Lameness

Accelerometer-based mobility scoring has focused on cow behaviors such as lying and walking. Accuracy levels as high as 91% have been previously reported. However, there has been limited replication of results. Here, measures previously identified as indicative of mobility, such as lying bouts and walking time, were examined. On a research farm and a commercial farm, 63 grazing cows' behavior was monitored in four trials (16, 16, 16, and 15 cows) using leg-worn accelerometers. Seventeen good mobility (score 0), 23 imperfect mobility (score 1), and 22 mildly impaired mobility (score 2) cows were monitored. Only modest associations with activity, standing, and lying events were found. Thus, behavior monitoring appears to be insufficient to discern mildly and moderately impaired mobility of grazing cows.

Farmers' perceptions and approaches to detection, treatment and prevention of lameness in pasture-based dairy herds in New South Wales, Australia

AIMS

The objective of this study was to investigate farmers' perception of lameness in comparison to the estimated prevalence of lameness in NSW pasture-based dairies to evaluate farmers' perceptions and approaches to detection, treatment and prevention of lameness.

METHODS

Across-sectional study was conducted on 62 pasture-based dairy farms across NSW, Australia. The prevalence of lameness in these farms was estimated using locomotion scoring (1-4 scale). A survey was also conducted, using a questionnaire and face-to-face interview, to explore farmers' perceived prevalence of lameness and approaches to treatment and prevention.

RESULTS

The prevalence of lameness estimated by farmers was 3.7 times less (mean: 5%; range 0% to 26%) than that determined by locomotion scoring (mean: 19.1%; range 5.0%-44.5%). Approaches to treatment included antimicrobial therapy, hoof inspection with or without application of wooden blocks. In 28% of the farms, the lame cows were managed by farmers or farm staff with no official training in treatment of lame cows. The mean interval from detection of lameness to examination of the affected hoof was almost 55 hours (range 2-720 hours). A very low percentage of farms kept lameness records or implemented lameness preventive strategies such as footbaths and prophylactic foot trimming.

CONCLUSIONS

Farmers and farm managers were found to underestimate the prevalence of lameness which could be due to the low level of awareness and can contribute to subsequent lack of implementation of prophylactic procedures and preventive management strategies for lameness. These findings accentuate the need to improve farmers' ability to detect lame cows and to emphasise the importance of recording in order to facilitate the management of lameness in dairy herds.

Effects of case definition and assessment frequency on lameness incidence estimates

The reliability of locomotion scoring is often low, making it unclear how a single gait score should be interpreted. In addition, differences in assessment frequency between longitudinal studies makes it hard to compare results. Our aims were to evaluate how lameness definition and assessment frequency affect measures of lameness incidence. Six dairy farms in British Columbia, Canada, were enrolled, and 262 cows that were sound at dry-off had their locomotion score (LS) assessed weekly from dry-off to calving, using a 1 to 5 scale. Cows were categorized as remaining sound or becoming lame using 3 different case definitions (LAME1: ≥LS3 at least once; LAME2: ≥2 consecutive scores of LS3, or ≥LS4 at least once; and LAME3: ≥3 consecutive scores of LS3, or ≥LS4 at least once). We analyzed the correspondence between the 3 definitions with percent agreement and weighted κ (linear and quadratic weighting). Comparing LAME1 to LAME3 resulted in lower percent agreement (53%) and κ values (linear κ_w = 0.50; quadratic κ_w = 0.64) than comparing LAME2 and LAME3 (85%; linear κ_w = 0.83; quadratic κ_w = 0.89), indicating that cows scored LS3 twice were likely to be scored LS3 a third time. We also compared the 3 case definitions against trim records from trimmings occurring 90 d or less before calving (n = 117), and used logistic regression models to determine sensitivity, specificity, and positive and negative predictive value. Using the LAME1 criterion resulted in high sensitivity (horn lesions = 0.90; infectious lesions = 0.92) and low specificity (horn = 0.21; infectious = 0.24). We observed higher specificity for LAME2 (horn = 0.62; infectious = 0.66) and LAME3 (horn = 0.71; infectious = 0.77), but LAME2 had higher sensitivity than LAME3 (horn = 0.89 vs. 0.64; infectious = 0.69 vs. 0.64). When evaluating the effects of assessment frequency, we obtained 3 data sets by keeping every, every other, and every third locomotion assessment, and using LAME2 as a case definition. More cows were categorized as lame when assessment frequency increased. Of the cows that were classified as lame when assessed weekly, 72% of the mildly lame, and 33% of the severely lame were classified as sound when assessed every third week. Our results suggest that a single LS3 score should not be used as a criterion for lameness in longitudinal studies. To correctly identify new cases of lameness, dairy cows should be assessed at least every 2 wk.

Evaluation of lameness detection using radar sensing in ruminants

BACKGROUND

Lameness is a major health, welfare and production-limiting condition for the livestock industries. The current 'gold-standard' method of assessing lameness by visual locomotion scoring is subjective and time consuming, whereas recent technological advancements have enabled the development of alternative and more objective methods for its detection.

METHODS

This study evaluated a novel lameness detection method using micro-Doppler radar signatures to categorise animals as lame or non-lame. Animals were visually scored by veterinarian and radar data were collected for the same animals.

RESULTS

A machine learning algorithm was developed to interpret the radar signatures and provide automatic classification of the animals. Using veterinary scoring as a standard method, the classification by radar signature provided 85 per cent sensitivity and 81 per cent specificity for cattle and 96 per cent sensitivity and 94 per cent specificity for sheep.

CONCLUSION

This radar sensing method shows promise for the development of a highly functional, rapid and reliable recognition tool of lame animals, which could be integrated into automatic, on-farm systems for sheep and cattle.

Aetiology, Risk Factors, Diagnosis and Control of Foot-Related Lameness in Dairy Sheep

During the last twenty years, considerable research efforts have recognized the consequences of foot-related lameness primarily in cattle, and meat and wool sheep. Despite the lack of extensive epidemiological studies, field observations and isolated research reports in dairy sheep have suggested that the problem might be more severe in semi-intensive and intensive farming systems. Footrot, contagious ovine digital dermatitis, ovine interdigital dermatitis, white line disease, and pedal joint abscess are the most common causes of foot-related lameness. Dichelobacter nodosus, Fusobacterium necrophorum, Treponema spp., and Actinomyces pyogenes are the most significant foot-related lameness-associated pathogens. Despite a documented hereditary predisposition, environmental factors are the most important in determining the occurrence of foot-related lameness. Moist and warm environment, increased parity and milk yield, inappropriate housing conditions and infrastructures, inadequate hygiene status, imbalanced nutrition, and insufficient foot care are the most critical risk factors. Furthermore, a foot-lameness control plan should include targeted implementation of claw trimming and footbathing, evidence-based planning of hygiene measures in preventive veterinary practices (i.e., antibiotic administration, vaccinations against footrot), selective breeding to footrot resistance, and, most importantly, the continuous training of farming personnel. Controlling foot-lameness in dairy sheep is critical in determining the well-being of animals, and strongly affects the farm's profitability and sustainability.

Risk of Lameness in Dairy Cows with Paratuberculosis Infection

Simple Summary

Johne’s disease (JD) is an important disease affecting cows in the UK dairy industry, as is lameness, and both cause milk production losses and cows losing weight. The aim of this work was to see if cows with JD were more likely to be lame and if so, what the order of occurrence of these two events is. We looked at the JD and lameness records of two farms and paired 98 JD cows (half of them with a high response to the test for JD) and compared them with herd mates. We evaluated the timing and the proportion of lameness in JD-positive cows compared to their controls and proportion of lameness before and after the first JD-positive test. JD cows turn lame on average three months earlier and are lame 2.7 times more often than non-JD cows. Further, high positive cows were 2.8 times more likely to develop lameness after JD diagnosis compared to medium positive cows. Results of this study suggest that there is a link between JD and lameness and that JD precedes lameness. The underlying mechanisms for this association remain unknown and were not the scope of this study.

Abstract

Johne’s disease (JD) is an important disease affecting the UK dairy industry, as is cattle lameness. An association between JD and lameness has been suggested; however, little evidence exists to support this. The purpose of this study was to determine if cows affected by JD were more likely to be lame and if so, what the temporal association is. Retrospective dairy cow mobility and JD status (based on milk ELISA) data were obtained from two farms of 98 JD cows (49 high and 49 medium positive) and their matched controls. We evaluated the timing and the proportion of (chronic) lameness in JD-positive cows versus controls and proportion of lameness before and after the first ELISA positive test. Compared to their controls, JD cows are lame more often (Odds Ratio = 2.7 (95% Confidence Interval = 1.2–6.0) p = 0.017) and became lame on average three months earlier (p = 0.010). High positive cows were more likely to develop lameness after seroconversion (OR = 2.8 (95% CI = 1.1–7.5), p = 0.038) versus medium positive cows. Results of this study suggest that there is a link between JD and lameness and that JD precedes lameness. The underlying mechanisms for this association remain unknown and were not the scope of this study.

Lameness in Beef Cattle: UK Farmers' Perceptions, Knowledge, Barriers, and Approaches to Treatment and Control

Lameness in the beef industry has received little attention in the UK, despite the fact that it is a well-recognised problem in the dairy industry. The aims of this study were to (i) compare UK beef farmers' estimates of lameness prevalence to that of researchers, (ii) explore beef farmers' attitudes towards lameness, and (iii) help identify farmer reported barriers to lameness control and treatment. Beef farmers (11 finishing units and 10 suckler farms) were recruited from England and Wales. Farmers were asked to estimate their lameness prevalence, before a researcher conducted locomotion scoring using a five point scale, and a Bland Altman analysis performed. Face to face interviews were also conducted using a semi structured interview script aimed at capturing information such as current approaches and protocols as well as their views of lameness importance. Interviews were recorded and transcribed. An inductive thematic analysis was performed. All but two farmers underestimated lameness prevalence on their farms when compared to the researcher. Farmers initially underestimated lameness prevalence compared to the researchers estimates, with a mean underestimate of 7% (95% CI 5–9%). This is an important barrier to lameness detection and treatment. Thematic analysis identified four major themes: (1). Perception of lameness prevalence, (2). Technical knowledge and skills, (3). Perception of the impact of lameness, and (4). Barriers to the treatment and control of lameness. This study highlights that some approaches to lameness treatment are likely to be causing harm, despite being done with the intention to help the animal. There were four key areas of concern identified: recognition of lameness, treatment approaches, the training provided to farmers and confusion over transport and slaughter options available to farmers. This suggests an urgent need for future work to quantify and address the problem, and to provide evidence to justify the role of prevention and potentially start to break down barriers to control and treatment of lameness.

Estimating the herd and cow level prevalence of bovine digital dermatitis on New Zealand dairy farms: A Bayesian superpopulation approach

A cross-sectional study of 127 dairy herds distributed across four regions of New Zealand (NZ) was conducted to estimate the regional herd-level prevalence of bovine digital dermatitis (BDD) and the prevalence of cows with BDD lesions within affected herds. Each herd was visited once during the 2016-2017 lactating season and the rear feet of all cows in the milking herd were examined to detect the presence of BDD lesions. Of the 127 herds examined, 63 had at least one cow with a detected BDD lesion. Of the 59 849 cows observed, 646 cows were observed with BDD lesions. All of the herds in which BBD was detected were located in three of the four regions (Waikato, Manawatu and South Canterbury). No convincing lesions were observed on the West Coast. The probability of BDD freedom on the West Coast was predicted to be 99.97% using a Bayesian latent class model. For the three regions where BDD lesions were observed, the true herd level and cow level prevalences were estimated using a Bayesian superpopulation approach which accounted for the imperfect diagnostic method. Based on priors obtained from previous research in another region of NZ (Taranaki), the true herd level prevalences in Waikato, Manawatu and South Canterbury were estimated to be 59.2% (95% probability interval [PI]: 44.3%-73.9%), 43.3% (95%PI: 29%-59%) and 65.9% (95%PI: 49.5%-79.9%), respectively, while the true median within-herd prevalences were estimated as 3.2% (95%PI: 2%-5%), 1.7% (95%PI: 0.9%-3.1%) and 3.7% (95%PI: 2.4%-5.5%), respectively. All of these estimates except for the true herd level prevalence in Manawatu were fairly robust to changes in the priors. For Manawatu region, changing from the prior obtained in Taranaki (the best estimate of the herd level prevalence = 60%, 95% sure > 40%) to one where the mode was 50% (95% sure < 80%) reduced the posterior from 43.3% to 35.2% (95%PI: 20.1%-53.5%). The marked variation in BDD prevalence between regions and between farms highlights the need for further exploration into risk factors for disease.

Radiographic assessment of cattle hoofs (ungulae) of the Nellore breed: Reference standards

The purpose of this work was to determine a radiographic standard of normality for lateral and medial ungulae in 3-year-old bovine females of the Nellore breed. Twenty-six cows underwent radiographic exposure of the medial and lateral ungulae of the hindlimbs and forelimbs; abaxioaxial projections were used. The images were analyzed; distances were measured between the dorsal surface of the distal phalanx and the surface of the hoof capsule. The two angles formed, i.e., an angle between the dorsal surface of the distal phalanx and a line parallel to the sole (inner), and an angle between the dorsal surface of the hoof and a line parallel to the sole (outer), were also recorded. The results suggested a standard of normality for the proximal, middle and distal distances of the ungulae of the forelimbs: 0.96 ± 0.12 cm. For the measurement of hindlimbs, except for the distal distances of the side ungulae, the suggested value was 1.02 ± 0.14 cm; for the distal measurement of the lateral ungulae of the hindlimbs, the value was 1.09 ± 0.12 cm. For inner and outer angles, the values were 36.45° ± 4.4° for the medial ungulae of the forelimbs and 42.50° ± 3.8° for other ungulae of the forelimbs and hindlimbs (standard deviations of the values suggested for the angles should be used as variations between different animals, limbs and ungulae; they should not be used between angles of the same ungula).

A longitudinal study of digital cushion thickness and its function as a predictor for compromised locomotion and hoof lesions in Holstein cows

Lameness is a major animal welfare and economic issue for the dairy industry and is a challenge to overcome due to multifaceted causes. Digital cushion thickness (DCT) is a strong predictor of lameness and is phenotypically associated with incidence of claw horn disruption lesions (CHDL; sole ulcers and white line disease). We hypothesized that DCT varies between digits and across lactation within the cow. This variation could be characterized to predict the occurrence of CHDL or compromised locomotion. BCS, visual locomotion score (VLS), DCT, and presence or absence of lesions were collected at 4 time points: <40 d prepartum (DPP), 1 to 30 d in milk (DIM), 90 to 120 DIM, and ≥255 DIM for 183 commercial Holstein cows enrolled in the study. Cows underwent digital sonographic examination for the measurement of DCT evaluated at the typical sole ulcer site beneath the flexor tuberosity for the right front medial and lateral digits and right hind medial and lateral digits. Factors such as parity number and stage in lactation were obtained from farm management software (DairyComp 305; Valley Agricultural Software, Tulare, CA). Cows were grouped by parity: primiparous (parity = 1) or multiparous (parity ≥ 2). The prevalence of CHDL among time points ranged from 0% to 4.2% for primiparous cows vs. 2.5% to 25% for multiparous cows, whereas the prevalence of lameness based on VLS of 3 to 5 ranged from 1.7% to 8.3% for primiparous cows vs. 12.7% to 33% for multiparous cows. DCT varied within primiparous and multiparous cows based on stage of lactation and digit (P < 0.05) and was thicker for both parity groups prior to dry off (≥255 DIM) and thinnest prior to calving (<40 DPP) and after peak lactation (90 to 120 DIM). The DCT of the front medial digit was thickest for primiparous heifers, whereas the hind lateral digit was thickest for multiparous cows. The DCT of the hind medial digit was thinnest for both parity groups. Parity group and DCT of the hind lateral digit <40 DPP were important predictors of CHDL (P < 0.05), whereas parity group and DCT of the hind lateral digit and front lateral digit at 1 to 30 DIM were key predictors of VLS lameness (P < 0.05). These results may help identify animals with higher odds of developing these diseases by highlighting key time points and specific digits of importance for monitoring. In addition, it improves our biological understanding of the relationship between DCT and lameness.

Optimising lameness detection in dairy cattle by using handheld infrared thermometers

Lameness is one of the most serious economic and welfare issues in the dairy industry. Early detection of lameness can be difficult, but provision of early treatment is crucial. Previous studies have used infrared thermography to show that increased foot temperature (FT) is associated with lameness and foot lesions. However, poor accuracy has limited the management application potential. This study analysed ambient-temperature (AT)-adjusted foot-surface temperatures and temperature differences between the hind feet of individual cows to enhance lameness detection. Cow FTs were recorded on a 990-cow farm using an infrared thermometer fortnightly for 6 months. Additionally, mobility level was scored using the AHDB Dairy 4-point scale. The averages of FTs and ATs were 23.83 ± 0.03°C and 13.99 ± 1.60°C, respectively. The FT of cows with lameness was significantly higher than that of cows without lameness (P < 0.001). Increases in FTs correlated with the mobility score (MS) (P < 0.001). According to receiver operating characteristic (ROC) curves, the optimal threshold based on actual FTs was 23.3°C with 78.5% sensitivity and 39.2% specificity. However, the ROC curve for the AT-adjusted FT and FT difference parameters showed minimal improvements over the FT in detecting lameness. In conclusion, the infrared thermometer results demonstrated the association between elevated FTs and lameness, but further improvements to this detection technique will be required before it can be implemented as a management tool for detecting cows that could benefit from treatment. With additional validation, the technique could be used as a screening device to identify cows in need of further assessment.

A Cross-Sectional Study Into the Prevalence of Dairy Cattle Lameness and Associated Herd-Level Risk Factors in England and Wales

Lameness is one of the most pressing issues within the dairy industry; it has severe economic implications while causing a serious impact on animal welfare. A study conducted approximately 10 years ago found the within farm lameness prevalence in the UK to be 36.8%. Our objective here is to provide an update on within farm lameness prevalence in the UK, and to provide further evidence on farm level risk factors. A convenience sample of 61 dairy farms were recruited across England and Wales from September 2015 to December 2016. A single farm visit was made and the milking herd was mobility scored, as the cows exited the milking parlor after morning, afternoon, or evening milking. Information regarding the farm and management system was then collected using a short interview with the farmer followed by collection of various subjective and objective measurements of the environment. The same, trained researcher performed all animal and facility-based measures on all visits. A series of univariable analyses were conducted to evaluate the association between various risk factors and herd lameness prevalence (logit transformed). A multivariable linear regression model was then fitted. The median number of milking cows per herd was 193, ranging from 74 to 1,519 cows. The mean within farm lameness prevalence was 31.6%, ranging from 5.8 to 65.4%. In total, 14,700 cows were mobility scored with 4,145 cows found to be lame (28.2%). A number of risk factors were associated with lameness at the univariable analysis level. Categorical risk factors retained in the final model were: resting area type, collecting yard groove spacing width, whether farms were undertaking the 60- to 100-day post calving claw trimming and the frequency of footbathing in the winter. The amount of concentrates fed in the milking parlors or out of parlor feeders was also associated with lameness prevalence. The results of this study have provided an update on the UK herd lameness prevalence and have confirmed the importance of cow comfort and footbathing frequency. The association between early lactation claw trimming and reduced lameness prevalence is, to the best of our knowledge, reported for the first time.

The contribution of previous lameness events and body condition score to the occurrence of lameness in dairy herds: A study of 2 herds

It has been demonstrated that low body condition and previous occurrence of lameness increase the risk of future lameness in dairy cows. To date the population attributable fraction (PAF), which provides an estimate of the contribution that a risk factor makes toward the total number of disease events in a population, has not been explored for lameness using longitudinal data with repeated measures. Estimation of PAF helps to identify control measures that could lead to the largest improvements on-farm. The aim of this study was to use longitudinal data to evaluate the proportion of lameness that could be avoided in 2 separate herds (2 populations) through (1) reduced recurrence of previous lameness events, (2) and moving body condition score (BCS) into more optimal ranges. Data were obtained from 2 UK dairy herds: herd A, a 200-cow herd with 8 yr of data from a total of 724 cows where lameness events were based on weekly locomotion scores (LS; 1 to 5 scale), and herd B, a 600-cow herd with data recorded over 44 mo from a total of 1,040 cows where treatment of clinical cases was used to identify lameness events. The PAF for categories of BCS were estimated using a closed equation appropriate for multiple exposure categories. Simulation models were used to explore theoretical scenarios to reflect changes in BCS and recurrence of previous lameness events in each herd. For herd A, 21.5% of the total risk periods (cow-weeks) contained a lameness event (LS 3, 4, or 5), 96% of which were repeat events and 19% were recorded with BCS <2 (3 wk previously; 0 to 5 scale). When lameness events were based on 2 consecutive weeks of LS 4 or 5, 4% of risk periods were recorded as lame, of which 89.5% were repeat events. For herd B, 16.3% of the total risk periods (consecutive 30 d) contained a lameness event (72.6% were repeat events) and 20% were recorded with BCS ≤2 (0 to 120 d previously). The median PAF for all previous lameness was between 79 and 83% in the 2 herds. Between 9 and 21% of lameness events could be attributed to previous lameness occurring >16 wk before a risk period. The median PAF estimated for changes in BCS were in the region of 4 to 11%, depending on severity of lameness. Repeated bouts of lameness made a very large contribution to the total number of lameness events. This could either be because certain cows are initially susceptible and remain susceptible, due to the increased risk associated with previous lameness events, or due to interactions with environmental factors. This area requires further research.

Mobility Scoring of Finished Cattle

Lameness is among the most important welfare and production issues affecting dairy cattle. Recently, it has received significant research emphasis. Certain events in 2013 within the cattle industry heightened the focus on mobility issues in finished cattle. Scoring systems are needed in the finished cattle industry to capture and measure mobility issues at packing facilities. The North American Meat Institute Animal Welfare Committee helped facilitate the creation of a scoring system to evaluate mobility of cattle at packing plants, providing the cattle industry with a tool to benchmark and improve the welfare of finished cattle.

Lateralized behaviour as indicator of affective state in dairy cows

In humans, there is evidence that sensory processing of novel or threatening stimuli is right hemisphere dominated, especially in people experiencing negative affective states. There is also evidence for similar lateralization in a number of non-human animal species. Here we investigate whether this is also the case in domestic cattle that may experience long-term negative states due to commonly occurring conditions such as lameness. Health and welfare implications associated with pain in lame cows are a major concern in dairy farming. Behavioural tests combining animal behaviour and cognition could make a meaningful contribution to our understanding of disease-related changes in sensory processing in animals, and consequently enhance their welfare. We presented 216 lactating Holstein-Friesian cows with three different unfamiliar objects which were placed either bilaterally (e.g. two yellow party balloons, two black/white checkerboards) or hung centrally (a Kong™) within a familiar area. Cows were individually exposed to the objects on three consecutive days, and their viewing preference/eye use, exploration behaviour/nostril use, and stop position during approach was assessed. Mobility (lameness) was repeatedly scored during the testing period. Overall, a bias to view the right rather than the left object was found at initial presentation of the bilateral objects. More cows also explored the right object rather than the left object with their nose. There was a trend for cows appearing hesitant in approaching the objects by stopping at a distance to them, to then explore the left object rather than the right. In contrast, cows that approached the objects directly had a greater tendency to contact the right object. No significant preference in right or left eye/nostril use was found when cows explored the centrally-located object. We found no relationship between lameness and lateralized behaviour. Nevertheless, observed trends suggesting that lateralized behaviour in response to bilaterally located unfamiliar objects may reflect an immediate affective response are discussed. Further study is needed to understand the impact of long-term affective states on hemispheric dominance and lateralized behaviour.

Effects of Manure Bedding on the Rate of Claw Diseases in Dairy Cows

This study was conducted to determine the prevalence of claw diseases in dairy cows housed on two different bedding systems: deep straw bedding and unsterilized recycled manure solids. On the farm (farm A) with the straw bedding, 403 and on the farm (farm B) with manure solid bedding, 226 dairy cows were examined. The prevalence of cows with one or more claw lesions on the farm with straw bedding and with manure solids were 37 % and 69 %, respectively (P < 0.001). In both bedding systems, two claw lesions dominated: digital dermatitis and inflammatory disorders of corium (white line diseases, toe ulcer, and sole ulcer). The prevalence of the digital dermatitis housed in deep-bedded freestalls and in freestalls with manure solids were 17.8 % and 53.1 % (P < 0.001), respectively. The prevalence of the white line diseases and toe ulcer were 12.1 % and 15.7 % on farm A and 3.88 % and 2.59 % on farm B, respectively (P < 0.001). There was no significant difference in the prevalence of the sole ulcer between farms. These data indicate a relatively high prevalence of claw lesions on the studied dairy farms. Moreover, a long-term contact of claws with manure (boxes and corridors) on the farm with unsterilized recycled manure solids seems to be associated with a higher prevalence of digital dermatitis.

Claw length recommendations for dairy cow foot trimming

The aim was to describe variation in length of the dorsal hoof wall in contact with the dermis for cows on a single farm, and hence, derive minimum appropriate claw lengths for routine foot trimming. The hind feet of 68 Holstein-Friesian dairy cows were collected post mortem, and the internal structures were visualised using x-ray µCT. The internal distance from the proximal limit of the wall horn to the distal tip of the dermis was measured from cross-sectional sagittal images. A constant was added to allow for a minimum sole thickness of 5 mm and an average wall thickness of 8 mm. Data were evaluated using descriptive statistics and two-level linear regression models with claw nested within cow. Based on 219 claws, the recommended dorsal wall length from the proximal limit of hoof horn was up to 90 mm for 96 per cent of claws, and the median value was 83 mm. Dorsal wall length increased by 1 mm per year of age, yet 85 per cent of the null model variance remained unexplained. Overtrimming can have severe consequences; the authors propose that the minimum recommended claw length stated in training materials for all Holstein-Friesian cows should be increased to 90 mm.