LAUSR

ABSTRACT How expressively and freely a horse moves depends on many factors. Two important factors are the slip resistance and riding safety of the surface on which it is moving. Numerous studies have already been carried out not only on how a horse places its feet on different types of surfaces but also on the cohesiveness of the footing surface with respect to the shear forces that are in action. Little is known at present, however, about the rotational shear resistance (RSR) of a footing, which is engendered by a horse hoof turning on its surface. In a technical investigation, the RSR (measured as the maximum moment of torque [TMax] which was necessary to turn a traction tester [TT] through 45°) of two different types of riding arena surface (sand [S] and sand fiber [SF]) were investigated according to their moisture content and the operator (operator A or operator B) using the TT. A subsequent 4‐week field study was used to investigate the effects of the factors sampling location, moisture content, number of days after the last arena grooming session, and the type of horseshoe stud on the RSR values (TMax) of an indoor riding arena surface. The RSR measurements were carried out daily for 4 weeks using the TT. The moisture content of the footing was determined before each of the RSR measurements in both the technical and field investigations. In the technical investigation, it could be shown that both the TT operator and the moisture content significantly influenced the TMax values, but not the footing composition. Despite standardized experimental conditions, operator B measured 12.73% higher TMax values than operator A when using the TT. There was a linear relationship between the moisture content and TMax values of both types of footing: the RSR of both the S and SF surfaces increased with increasing moisture content. There was, however, no significant difference in the RSR between the two types of footing. In the field investigation, the sampling location in the indoor riding arena, the number of days after the last arena grooming session, the use of studs, and the moisture content all had a significant influence on the TMax values. Significant differences in TMax occurred depending on the sampling location in the indoor riding arena. Arena grooming led to a significant reduction in the RSR of the footing, although only on the day when the grooming took place. The use of studs led to 27.47%–65.18% higher TMax values than when no studs were used. Important for the increase in TMax values was the stud length as higher TMax values could be measured with increasing length. Furthermore, a linear relationship between the moisture content and the TMax values could be observed in the experiments without studs. HIGHLIGHTSRotational shear resistance (RSR) is an important functional property of riding surfaces.Rotational shear resistance (TMax) values depended on the traction‐tester operator.Increasing moisture content led to an increase in the RSR of the footing.Rotational shear resistance was significantly reduced directly after grooming the footing (dragging and watering).Higher RSR (TMax) values were found when studs were used on the horseshoes.