Slatted Floors and Solid Floors: Stress and Strain on the Bovine Hoof Capsule Analyzed in Finite Element Analysis

Risk factors associated with indicators of dairy cow welfare during the housing period in Irish, spring-calving, hybrid pasture-based systems

In a dairy production system where cows are grazing for a large portion of their lactation, little attention has been afforded to investigating multiple indicators of welfare for risk factors associated with the housing period. Yet regardless of the length of the housing period, cows still experience the positive and negative welfare impacts of both indoor and outdoor environments in a hybrid system. Thus, the objective of this study was to identify risk factors for indicators of dairy cow welfare during the housing period in a spring-calving, hybrid pasture-based system. Herd-level scores for seven indicators of welfare (locomotion, body condition, ocular and nasal discharge, integument damage, tail injury and human avoidance response) were collected from 82 Irish dairy farms during the housing period (October - February). Data were analysed using multiple beta regression or zero-inflated beta regression to identify associations between these welfare indicators and measured herd-level housing, resource and management factors. Thirty-six unique risk factors were associated with one or more welfare indicators (P < 0.05). Analyses identified two risk factors for body condition < 3.0 and four for body condition > 3.5, the target range during the housing period. Four risk factors were identified for each of ocular discharge, nasal discharge and avoidance response of > 1 m from human approach. Six risk factors each were associated with the proportion of lame cows and integument damage to the head-neck-back or hindquarter regions. The greatest number of risk factors, 12, were associated with tail injury (broken, lacerated or incomplete tails). Risk factors associated with multiple indicators of welfare were cow comfort index (tail lacerations and hindquarter integument damage), cubicle width (broken and incomplete tails), shed floor slipperiness (lameness and head-neck-back integument damage), shed light-level (tail lacerations, avoidance response and below target body condition), shed passage width (broken tails and head-neck-back integument damage) and presence (incomplete tails) or absence (broken tails) of a collecting yard backing gate. With the large number of risk factors associated with tail injury, continued research is necessary to identify causes and determine prevention methods to contribute to improved overall welfare of dairy cows. Housing features meeting recommended guidelines from the literature were frequently associated with greater negative indicators of welfare. In light of this, housing guidelines may benefit from regular re-evaluation to ensure facilities meet the welfare needs of cows during the housing period.

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.

Thirty Years of Changes and the Current State of Swedish Animal Welfare Legislation

Simple Summary

Sweden is often cited as a leading country in animal welfare and related legislation, but some recent changes in the national legislation are seen as lowering the animal welfare requirements in order to improve the competitiveness of Swedish farmers. In this study, we analysed suggested changes to the Swedish welfare legislation between 1988 and 2019 relating to horses, cattle and pigs, including the written motivations, the written stakeholder responses and the actual changes to the final regulations. We used a sample of 77 legal requirements to assess in depth whether the animal welfare level was affected by these changes in the legislation. The results showed that the animal welfare requirements in Sweden for cattle, pigs and horses increased overall during the 30-year study period, but that a number of specific requirements had been relaxed to satisfy interests other than animal welfare. Thus, the new requirements should be evaluated more fully in order to determine whether they serve their purpose in practice.

Abstract

Sweden is often seen as a leading country in animal welfare and legislation, but some recent amendments to the legislation are perceived as relaxing animal welfare requirements in order to improve the competitiveness of the relevant industry and of farmers. In this study, we analysed the suggested and actual changes in the Swedish national animal welfare regulations relating to horses, cattle and pigs between 1988 and 2019 and the consequences for the intended animal welfare level. The regulations and amendments, including the proposals, the written motivations, the stakeholders’ written responses to the proposed amendments and the final amendments, were scrutinised in detail. A sample of 77 requirements was then selected to assess whether and how the animal welfare level was affected by these legislative changes. The results indicated that the animal welfare protection level for cattle, pigs and horses increased overall during the 30-year period, but that a number of specific requirements had been relaxed to meet objectives other than animal welfare. It was more difficult to determine whether animal welfare improved in practice during the same period, due to the lack of systematic evaluations of the consequences of amending the regulations. Future evaluations are needed to evaluate the outcome of new legislative requirements and to monitor whether they serve their purpose in practice.

Changes in hoof health and animal hygiene in a dairy herd after covering concrete slatted floor with slatted rubber mats: a case study

The objective was to investigate the effect of changing the flooring in the alleys of a barn from slatted concrete to slatted rubber mats on hoof disorders and animal hygiene in 44 loose-housed Brown Swiss dairy cows. Cows were examined for disorders of the hind hooves (hemorrhages, white line fissures, ulcers, heel horn erosion, and digital dermatitis) and for skin lesions. The dirtiness of the animals and of the floor was recorded. Climatic (temperature, humidity) and ammonia gas conditions were measured. Evaluations were carried out when the cows were housed on a concrete slatted floor and after 4 and 10 mo on soft flooring (slatted rubber mats, 29-mm thick). The anatomical portion of claw (medial, lateral), number of lactations (parity), and days in milk were included as covariates in the statistical model. Changing the flooring from slatted concrete to slatted rubber mats increased the score for white line fissures [1.0 ± 0.3 (concrete) vs. 2.5 ± 0.4 (10 mo rubber mats)] and influenced air humidity (i.e., the difference in the absolute humidity between the inside and outside of the barn increased from 1.5 ± 0.1 to 1.7 ± 0.2g/m(3)), whereas the other hoof disorders, skin lesions (score of 8.7 ± 0.3), the dirtiness of the animals (score of 5.9 ± 0.3), and the floor (score of 2.1 ± 0.1), and ammonia gas concentration (2.6 ± 0.3mg/kg) were not affected (overall scores or measures; mean ± SE). Lateral claws were more affected (except for heel horn erosion) than medial claws (estimated effects between 1.3 ± 0.2 and 3.0 ± 0.6). Parity influenced hoof disorders (except for hemorrhages) and skin lesions (estimated effects between -0.6 ± 0.3 and 0.5 ± 0.2). Days in milk influenced hoof disorders, but had no effect on skin lesions and on the dirtiness of the animal. Irrespective of floor type, the slots (2.6 ± 0.1) were dirtier than the slats (1.6 ± 0.1). In conclusion, covering slatted concrete flooring with slatted rubber mats partially impaired hoof health but did not influence skin lesions or the dirtiness of the cows or the floor. Similar results were found for climatic conditions, as ammonia gas concentration was not affected, but absolute humidity increased in the barn when rubber mats were present.

Assessment of lameness prevalence and associated risk factors in dairy herds in England and Wales

Visits were made to 205 dairy farms in England and Wales between October 2006 and May 2007 by 1 or more of 4 researchers. At each visit, all milking cows were locomotion scored (lameness scored) using a 4-point scale (0=sound locomotion, 1=imperfect locomotion, 2=lame, 3=severely lame). The mean prevalence of lameness (scores 2 and 3) across the study farms was 36.8% (range=0-79.2%). On each farm, the presence within the housing and grazing environments of commonly reported risks for increased lameness was recorded. Each farmer was interviewed to gauge the ability of the farm staff to detect and treat lameness. A multivariable linear regression model was fitted. Risk factors for increased lameness were the presence of damaged concrete in yards, cows pushing each other or turning sharply near the parlor entrance or exit, cattle grazing pasture also grazed by sheep, the use of automatic scrapers, not treating lame cows within 48h of detection, and cows being housed for 61 d or longer at the time they were locomotion scored by the visiting researcher. Having a herd consisting entirely of a breed or breeds other than Holstein-Friesian was associated with a reduction in lameness prevalence compared with having a herd consisting entirely of Holstein-Friesians.

White-line disease and haemorrhages in hooves of Finnish dairy cattle

The Finnish Healthy Hooves Project was set up to determine the frequency of, and risk factors for, various hoof lesions in Finnish dairy herds. Data were collected in 2003 and 2004. A large data set of >74,000 cow-level observations recorded by hoof-trimmers were merged with production data from the Finnish Agricultural Data Processing Centre Ltd. Ultimately, data from a single lactation from each of 16,727 cows in 703 herds were used for analyses of white-line disease (WLD) and haemorrhages-lesions. Three-level hierarchical logistic models with hoof-trimmer and farms (within hoof-trimmer) as random-effects were fit to datasets of tie-stall (TS) and loose-housing (LH) herds separately. Cows examined once had a WLD risk of 4.8% in TS herds and 17% in LH herds. As the number of examinations increased, the odds of a WLD diagnosis increased substantially; (2 and 3+ examinations had odds ratios (ORs) of 2.57 and 3.40 in TS herds and 2.32 and 4.67 in LH herds, respectively, compared to 1 examination). Parity had an interaction with breed in all models in TS and in the LH haemorrhages model, but not in WLD LH models. In TS herds, older Holstein cows had a very high risk of WLD compared to young Ayrshire cows (OR=7.92). Also in LH herds both breed and parity had association with WLD (Holstein cows were 1.57 times more likely than Ayrshire cows and cows in parity >or=4 were more likely (OR=2.89) than parity 1 to get WLD). In TS herds, other hoof lesions - such as haemorrhages (OR=1.65), heel-horn erosions (OR=1.77), and corkscrew claw (OR=1.82) - increased the risk of WLD. In LH herds, corkscrew claw (OR=1.59) and heel-horn erosion (OR=0.72) had a significant association with WLD. In TS herds, use of mats (compared to hard flooring) significantly reduced the risk of WLD and haemorrhages (OR=0.57 and OR=0.80, respectively). No significant associations of the 305-day milk production on the risk of either disease were observed in either TS or LH herds (305-day milk yield from each cows' previous lactation were used for calculations, with herd average yield and the individual cow's deviation from the herd average being used as predictors).

Comparison of Stress Zones in Finite Element Models of Deformed Bovine Claw Capsules

Pathological claw formations occur subsequent to irregular or prolonged claw trimming periods and as a result of improper flooring. Clinical experience and material testing finds horn of minor quality to be associated with the malformations. Finite element models (FEM) of a flat claw (FC), a contracted claw (CC), and a laminitic claw (LC) were designed from native claw specimens to combine material properties and altered claw geometry for stress analysis. The FEM were created by digitizing the typically deformed exungulated claw capsule by means of computed tomography or digital photography. The derived geometry data were meshed with finite elements and the material properties were attributed. Loading was performed via vertical load vectors according to the suspensory and support apparatus of the bovine digit. All FEM were loaded on soft floors. Loading of the FEM of the FC with 756 N exhibited maximum stress values of 3.32 MPa in the dorsal wall, that of the CC exhibited comparably lower stress of 1.33 MPa in the distal abaxial wall, and the model of the LC showed maximum stress of 4.51 MPa in the region of the dorsal border, all at the same loading. The solar surfaces and the corresponding imprints showed stress concentrations in the palmar aspect of the bulb in the FC, a highly stressed bearing margin of the abaxial wall in the CC, and a diffusely stressed sole and bulb in the LC in contrast to the sound claw models. The FEM of the selected pathological claw forms (FC, CC, LC) calculated high stress zones exactly at locations in the claw wall and sole where clinical experts expect the typical claw lesions for these pathologies. These results were obtained simply by exchanging the outer form of the claw capsules; the method of loading and type of flooring for these pathological models were equivalent to those of the sound FEM. It is highly possible that the stress zones derived from these calculations represent corium compression in reality, and these data support the pathophysiological theory that claw lesions may arise as a consequence thereof.