Effects of induced weight shift in the hind limbs on claw loads in dairy cows.

The modern dairy industry is plagued by a high prevalence of claw horn lesions in cows, which cause lameness, affect well-being, limit milk production, and are responsible for premature removal of cows from the herd. The lateral hind claws are primarily affected, and this has been linked to a relatively higher load being exerted on the lateral claws when cows shift weight from one hind limb to the other. The vertical ground reaction forces and mean and maximum pressures under the claws were measured in 40 nonlame dairy cows before and during a shift in weight from one hind limb to the other, which was accomplished by applying pressure manually to one side of the pelvis. During square standing on firm ground, about two-thirds of the entire hind limb load was exerted on the 2 lateral claws, and the remaining one-third was exerted on the medial claws combined. At the moment of maximum weight shift, the lateral claw of the loaded limb bore almost two-thirds of the entire load of both hind limbs, with the heel zone bearing almost half of the load of both hind limbs. Subsequently, the load of the lateral claw of the contralateral hind limb decreased, as did the load of both medial claws. Thus, the weight redistribution had occurred predominantly between the lateral hind claws. The high load exerted on a lateral hind claw during weight shift and at maximum weight shift is assumed to play a role in the pathogenesis of claw horn lesions, particularly when accentuated by a softened claw horn and hard flooring.