The locomotion of dairy cows on floor surfaces with different frictional properties

The locomotion of dairy cows was evaluated on floors with a smooth epoxy re sin surface or with a surface-applied bauxite aggregate of mean diameter 0. 5, 1.2, or 2.5 mm (coefficients of static friction, mu 0.35, 0.42, 0.49, an d 0.74, respectively). Locomotion was recorded as cows walked to receive a food reward. Cows on the floor with least friction walked rapidly (0.85 m/s ), with frequent, short steps. At the start of the supporting phase the upp er limbs were more vertical. Joint arcs during this phase were reduced. Cow s on 0.5-mm aggregate also walked rapidly (0.84 m/s); they had the least ve rtical limb angles and long steps but held the hoof more vertical, probably to offset any increased slip risk. On floors with larger aggregate, cows d ecreased speed and step frequency but maintained long steps, keeping their upper forelimbs more vertical to reduce the supporting limb phase. It is co ncluded that on a low friction floor (mu < 0.4), cows walk quickly with fre quent, short steps. As <mu> increases to 0.5, step length increases and the number of steps decreases to maintain speed at increased friction, produci ng an optimal coefficient of friction between 0.4 and 0.5. Further increase s in mu may increase the hanging limb phase at the expense of the supportin g limb phase, to reduce friction, while maintaining a long stride to expedi te arrival at the reward.