Frictional interactions between bovine claw and concrete floor

Inadequate properties of concrete floors in cattle houses are a major cause of claw problems, resulting in economic losses and impaired animal welfare. Many claw diseases are sequels of an extreme local overload due to high floor roughness or are caused by the indirect effects of the slipperiness of the floor. In this paper, the roughness of the concrete floor, the frictional interactions between bovine claw and floor and the relation between roughness and frictional properties, are studied. Concrete floor samples were made with five different finishing methods. Their roughness was determined by measuring the heights of the ‘peaks and valleys’ of the surface with a high-precision laser beam. The smoothest surface was the sample finished with a metal float (average surface roughness R a =0·080 mm) and the roughest surface occurred with the heavily sandblasted sample (average surface roughness R a =0·296 mm). Their roughness was also approximated with the ‘sand-patch’ method: the texture depth was calculated by dividing a fixed volume of fine dry sand by the surface area of the circle-shaped sand patch. Again the smoothest surface appeared to be the sample finished with a metal float (texture depth=0·19 mm) and the roughest surface was the heavily sandblasted sample (texture depth=0·59 mm). The sand-patch method appeared to be a reliable way of assessing the roughness of the floor. The static coefficient of friction μ stat and the dynamic coefficient of friction μ dyn between bovine claw models and dry and wet floors were determined by using the ‘drag method’ (a loaded bovine claw was dragged using a hand-operated winch over a flat floor sample while the tensional force was recorded). The five concrete floor panels with different roughnesses were used, but also two types of synthetic floor coverings (mat and mattress) were added to the test. The static coefficient of friction on dry floors varied between 0·60 (mattress) and 0·79 (mildly sandblasted concrete); the dynamic coefficient of friction ranged between 0·47 (mattress) and 0·69 (heavily sandblasted concrete). In wet circumstances only three floor types were tested. The static coefficient of friction varied between 0·65 (metal-floated concrete) and 0·80 (heavily sandblasted concrete) while the dynamic coefficient of friction yielded values between 0·56 (metal-floated concrete) and 0·69 (heavily sandblasted concrete). Significant differences were found between the floor types, but these were mainly due to the values measured on the metal-floated concrete, the mattress and the mat. Only in dry circumstances did the fore claws produce significantly higher coefficients of friction than the hind claws. The effect of the floor type on the coefficients of friction was in all cases many times higher than the effect of the claw itself. The static and the dynamic coefficients of friction in wet conditions were found to be larger than the same coefficients in dry conditions. The skid or slip resistance was measured separately, on wetted surfaces, with the skid-resistance tester (SRT) pendulum. The values found ranged between 20·2 (metal-floated concrete) and 49·6 (mattress). Significant differences between the floor types were found. Significant correlations were found between the static and the dynamic coefficients of friction, in dry and wet conditions, and the roughness values R x and the texture depth. Significant correlations were also found between the SRT values and the roughness values R x . Significant correlations were found only between the dynamic coefficients of friction and SRT values. The measured coefficients of friction were all higher than the required coefficients of friction, hence the tested floor samples provided enough resistance against slip.