The feather, beaks, hoofs, and animal scales generally consist of rigid and tough protein
beta-sheeted keratin [2]. The rigidity and toughness of the beta keratin on the one hand
related to the occurrence of higher sulfur content (S–S bond) and on the other, it allows
sterically unhindered hydrogen bonding between the amino and carboxyl groups of peptide
bonds on adjacent protein chains, facilitating their close alignment and strong binding. The
keratin found in hair, skin, and callus is more flexible for their alpha helical nature [3, 4]. The
beta keratin occurrence in feather, especially, is over 90% [2].