Keratin is a structural protein and serves as the primary constituent of hair, horns, feathers, wool, and the stratum corneum of the skin. Its notable characteristic, distinguishing it from other similar proteins, is its high content of the amino acid cysteine. Human hair typically contains between 14-15% cysteine, contributing significantly to its strength. Because of these properties, keratin functions both as an internal structural protein and as an external protective protein. Moreover, keratin aids in reducing water evaporation from the epidermal layer. This dietary supplement is rich in amino acids and crude protein, making it suitable for incorporation into animal feed formulations for livestock, poultry, and aquatic species.