The properties of three prepared biopolymers were compared for use as fillers for XNBR: cattle hair keratin derived from tanning industry wastes, its hydrolysate, and the hydrolysate of bird feathers obtained from poultry wastes. The incorporation of the prepared biopolymers into XNBR elastomer results in new composites that have good strength parameters, ranging from 13 to 16 MPa, and that are resistant to thermal aging and the action of oils and fuels. An additional feature of these composites is their increased susceptibility to the action of microorganisms; consequently, they are more easily biodegradable.