Industrial rendering

Industrial rendering is a factory-scale process that uses slaughterhouse waste, restaurant grease, and butcher shop trimmings as its raw materials. This material can include the fatty tissue, heads, bones, offal, and other waste animal parts. The rendering process simultaneously dries the material and separates the fat from the bone and protein. After rendering, the materials are much more resistant to spoiling. The fat can be used in animal feed, in soap-making, in candles, as a raw material for biodiesel production, and as a feed-stock for the oleochemical industry. The bone and protein becomes dry particles known as meat and bone meal. Hooves and horns are rendered to produce adhesives and gelatin.

For many years meat and bone meal were fed to cattle. This practice is now prohibited in developed countries because it is believed to be the main route for the spread of BSE (mad-cow disease). Meat and bone meal is still fed to non-ruminant animals in the United States.