3 Sources of KeratinSources of keratin include wools, nails, hairs, hooves, feathers, reptilian scales, and avian (Fig. 2). Reptilian scales, feathers, and avian display almost similar keratin genes (Gregg et al. 1984), and it has been also proved that these feathers and scales are β-sheet based on transmission electron microscope (Filshie et al. 1964) and X-ray diffraction patterns (Astbury and Marwick 1932; Fraser and Parry 2008).