How do different frequencies of outdoor access influence the gait and hoof health of non- clinically lame cows housed in a movement restricted environment?

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). [...]