Animal fat is rendered or extracted fat. Restaurant grease has become a major component of feed-grade animal fat. It is stabilized with powerful antioxidants to retard spoilage, and then sprayed directly onto extruded kibble to increase palatability. Mmmm…Rendering, as defined by Webster's Dictionary, is "to process as for industrial use: to render livestock carcasses and to extract oil from fat, blubber, etc, by melting." (Dr Corinne Chapman, Rocky Ridge Vet Care)