How do different frequencies of outdoor access influence the gait and hoof health of non-clinically lame cows housed in a movement restricted environment?
Authors: S. Mokhtarnazif and E. Shepley
Date: 2022-09-01
Status: Published
Objective
The objective of our study was to evaluate the effects of 1 vs 3 days per week of access to an outdoor exercise yard on gait and hoof health of non-lame cows housed in tie-stalls as a model of cows kept in a movement-restricted environment. Our previous study utilized a similar design but with different treatment groups (1h 5d/week outdoor access vs. no outdoor access) and demonstrated an overall gait improvement of 1 score in cows receiving 5 weeks of outdoor access. Based on this, we hypothesized that providing lower frequencies of outdoor access for movement-restricted cows would also yield levels of positive outcomes on gait. We also hypothesized that provision of outdoor access will not lead to any detrimental effects on hoof health.
Materials and methods Thirty-six lactating Holstein cows housed in tie-stall were enrolled in the study and blocked by parity and DIM (n=6/block). Cows were randomly assigned to one of two exercise treatments: cows receiving outdoor access for 1h/d 1d/week (Exercise1x) or 3d/week (Exercise3x) for 5 weeks. Overall gait and 6 gait attributes (swinging out, back arch, tracking-up, joint flexion, asymmetric step and reluctance to bear weight) were assessed by one observer using a 5-point visual gait scoring at three data collection periods: before the start of the study (Pre-trial), at the end of the study (Post-trial), and 8 weeks after the end of the study (Follow-up). Clinical assessment of claw lesions was conducted during hoof trimming at Pre-trial and Follow-up. Number, location and severity score of claw lesions were recorded. Overall gait, gait attributes, and severity of lesions were analysed using linear mixed effect models (α < 0.05), whereas lesions were analysed using mixed effect logistic regression models (α < 0.05).
Results The average gait score for cows in Pre-trial, Post trial and Follow-up were 2.13 (Min: 1.5, Max: 3.5), 1.98 (Min: 1, Max: 3.5) and 2.02 (Min: 1, Max: 3), respectively. Regarding cows that scored ≥3, there were 3 in the pre-trial, 3 in the post-trial, and 2 in the follow-up period. There were no statistically significant differences for the changes in overall gait and gait attribute scores between the treatment groups and periods (P > 0.05). Throughout the experimental period, the observed change in the overall gait score was -0.13 ± 0.18 and -0.13 ± 0.17 for Exercise1x and Exercise3x, respectively (P > 0.05). Sole (n=39, average severity score = 1.26 ± 0.36) and white line hemorrhages (n=2, average severity score=1.5 ± 0.29) were the only claw lesions observed. Between Pre-trial and Follow-up, the prevalence of claw disorders did not change (P > 0.05) for Exercise1x (5.56% to 6.62%) or Exercise3x (9.72% to 6.94%). Similarly, the severity scores of claw lesions were not statistically different between treatment groups and periods (P > 0.05).
Conclusion
Contrary to our hypothesis, the preliminary evaluation of gait in the current study showed that changes in gait scores for cows provided with 1h 1d/week or 3d/week are negligible. It suggests that lower frequencies of outdoor access may not be sufficient to benefit gait compared to 1h 5d/week outdoor access. However, given that we did not target clinically lame cows upon enrollment, the small changes in gait that may occur between treatment groups over the 5-week application period may not be recognizable by visual gait scoring alone. Therefore, to precisely determine the impact of providing outdoor access on gait, kinetic and kinematic measurements of gait have been acquired through a pressure mapping system and a 3D motion analysis system for further analysis. The results of claw lesion assessment corroborated our previous study and showed that lower frequencies of outdoor access had little impact on claw lesions development in movement-restricted cows. However, to detect hoof pathologies at early/subclinical stages, the analysis of thermal images of cow’s hooves is currently underway.