Mokhtarnazif, S.; Nejati, A.; Shepley, E.; Dallago, G. M.; Diallo, A. B.; Vasseur, E.

Most common housing systems for dairy cows restrict their movement, which can influence welfare, gait, and hoof health of dairy cows. Outdoor access has been proposed as a management practice to offset these restrictions, but reported effects on cows' locomotion vary and may not always be captured by traditional clinical assessments. In this study, we investigated gait and hoof through clinical (i.e., visual locomotion scoring and hoof lesion assessment) and subclinical (3D motion analysis, kinetic assessment, hoof infrared thermography and measuring claw conformation) methods to assess how limited provision of outdoor access affects non-lame cows housed in movement restricted environment. Thirty-six Holstein tie-stall cows were either given 1day/week (EX1) or 3days/week (EX3) of outdoor access (1h/day) during 5 consecutive weeks. Clinical and subclinical assessments of gait and hoof were performed before (Pre-trial), after 5 weeks of outing (Post-trial) and 8 weeks after outing (Follow-up). The results of this study revealed no clinical effect of outdoor access on cows' locomotion score and hoof lesion prevalence. However, for subclinical assessment, both groups showed an increase in stride and stance time at Post-trial, with an increase in pressure applied by cows while standing in EX3 group and a reduction in coronary band temperature in both groups at Post-trial and Follow-up. Contact area and claw conformation changed after provision of outdoor access in both groups. This study illustrates that with the use of subclinical methods; we can reveal effects of outdoor access on gait and hoof health that might not be visible using the traditional methods.