The Young's modulus of ostrich claw keratin

Samples of the keratinous covering of ostrich claw were prepared and were tensile tested. The Young's modulus of the specimens was calculated from the initial, steepest portion of the load-displacement curve. The mean Young's modulus values were 1.84 GPa and 1.33 GPa, respectively along and perpendicular to the claw length. Comparing these values with those reported for hoof keratins from mammals suggest a mechanical anisotropy that arise from the orientation of the keratin. Basic fibrous composite theory then suggests either a structure made of a matrix almost as stiff as the fiber, or the claws and hooves are either laminate or multidirectional composites.