Three major types of feed processing include Pelleting, Extruding, Roasting.  Pelleting is the process of turning mash into pellets with a hydraulic press. The pellets are highly compact. They are sold in bags, frozen, just like the feed you buy for your cat or dog at the supermarket. Extrusion cooking is a simple and inexpensive method of transforming ingredients into something completely different. For example, extrusion can handle almost any dry or semi-dry ingredient — grains, oilseeds, nuts, and dried fruit and turn them into tastier non-human food for animals. Roasting is used for cooking meats, vegetables, or a fish meal with dry heat. It is a type of baking and thus a form of food processing for preparing animal feeds.