Shape Directional Asymmetry in Hindlimb Pairs among Calves (Bos Taurus)

SIMPLE SUMMARY: In biological structures, the shape can be different between the right and left sides. The geometric morphometry technique can contribute to finding these differences by measuring the degree of deviation known as asymmetry. Deviations can occur in response to environmental stress, biomechanical pressures, genetic effects or lateralized behavior. The aim of this study was to determine the degree of asymmetries in the autopods of the hind limbs in healthy Brown Pyrenean calves, using the geometric morphometry (GM) technique. In a slaughterhouse, post-mortem samples of 28 autopods (right–left) were taken from the hind limbs. Dorsoplantar radiographs were obtained for each autopod, and then the bone shape was compared in right–left pairs using 15 landmarks. The results show that the right and left distal extremities present a certain degree of symmetry, but they develop differently in direction; the right hind limbs tend to rotate outwards, and the left hind limbs tend to rotate inwards. The results stimulate the evaluation of the function of each hind limb of cattle during standing and locomotion. This study can be considered as the first symmetric structural investigation of this cattle using geometric morphometry. ABSTRACT: The aim of this study was to determine paired asymmetries (right–left) in the autopods of bovine hindlimbs using geometric morphometry (GM). A total of 28 hindlimb right–left matched autopods belonging to healthy Brown Pyrenean calves were assessed. Dorsoplantar radiographs were obtained for each autopod. The bone shape was compared on right and left pairs by means of GM techniques, using a set of 15 landmarks. The results suggest that right and left distal limbs are, despite a perceived resemblance of symmetry, differently directionally developed in shape, with right hindlimbs tending to supinate (rotate outwards) and left hindlimbs tending to pronate (rotate inwards). This unevenness is probably related to the mediolateral forces’ contribution of each limb in carrying out the tasks of propulsion and control during walking, and/or a consequence of a laterality associated with a lateralized grazing posture. Our findings prompt a new reassessment of the function of each bovine hindlimb during standing and locomotion.