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

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

Prevalence and Causes of Normal Exercise Oximetry in the Calf in Patients with Peripheral Artery Disease and Limiting Calf Claudication.

OBJECTIVE: In patients with claudication, an ankle brachial index (ABI) under 0.90 is considered to be abnormal and a sufficient argument for the arterial origin of exercise induced pain. Exercise transcutaneous oxygen pressure (Ex-tcpO2) can provide evidence of exercise induced regional blood flow impairment (RBFI) and confirm the arterial origin of walking induced pain. The frequency with which calf Ex-tcpO2 remains apparently normal in patients with claudication and abnormal ABI is unknown. Causes of these discrepant results have yet to be analysed. METHODS: A retrospective analysis of 4575 Ex-tcpO2 tests performed on 3,281 patients was conducted. The focus was on patients with a history of calf claudication and ABI under 0.90. Duplicate or non-standard tests were excluded, as were patients with no pain or those able to walk more than 15 minutes (on a treadmill). Searches were conducted for possible explanations of normal calf Ex-tcpO2 in the selected patients. RESULTS: Cardiorespiratory limitation was identified in 50 patients and isolated non-calf ischemia in 36 of the 106 patients selected. There was no obvious explanation during Ex-tcpO2, but clinical improvement after non-vascular treatment or total absence of improvement after a technically successful revascularisation was noted in 12 patients. Four patients were lost on follow up. Four patients improved after revascularisation, which suggests that the Ex-tcpO2 result was false negative. CONCLUSIONS: Ex-tcpO2 is negative in more than 20% of tests performed in patients with an ABI under 0.90 and a history of calf claudication. In most cases, when excluding re-tests and non-limiting or non-calf claudication on the treadmill, non-calf ischemia or a non-vascular limitation occurring during the test were observed. This observation supports both the value of treadmill testing in patients with calf claudication assumed to be of arterial origin (ABI<0.90) and the use of Ex-tcpO2 to detect non-calf ischemia.

Chest tcpO2 changes during constant-load treadmill walking tests in patients with claudication.

Changes in chest transcutaneous-pO(2) at rest (ΔtcpO(2)) mimic absolute changes in arterial-pO(2) during moderate exercise, although the absolute starting values may dramatically differ. We retrospectively studied 485 patients (group 1), prospectively studied 292 new patients (group 2) and estimated the intra-test and the test-retest reproducibility of ΔtcpO(2) during constant-load treadmill tests: 3.2 km h(-1), 10% grade, using the cross correlation technique. Patients were classified into groups according to their best fit to nine pre-defined mathematic models. Respectively, 71% and 76% of patients of groups 1 and 2 fitted with a model showing a ΔtcpO(2) increase during and a decrease following exercise. Another 18% and 12% of the patients of groups 1 and 2 respectively fitted with a model that showed an abrupt decrease at exercise onset, a slow increase during walking and an overshoot in the recovery period, referred here as a walking-induced transcutaneous hack (WITH) profile. The mean r(max) value for the cross-correlation analysis was 0.919 ± 0.091 and 0.800 ± 0.129 for intra-test and test-retest reproducibility. Most profiles show the expected ΔtcpO(2) exercise-induced increase. Future studies are needed to confirm and explain the WITH profiles that we found, and screen for potential-associated diseases.