But what of the inedible parts? Parts like bones, bladders, diaphragms, lungs, sphincter muscles, fat and gristle. Or external parts: heads, feet, hooves, skin, hair or udders? Or the liquids - the blood and urine? And solids - the faeces and stomach contents? None of this is of any use to the human food industry. Yet it accounts for about 49% of a cattle carcass....