ABSTRACT
Digestive mechanisms provide the animal with a means of reducing complex dietary materials into forms suitable for absorption and utilization by the body. Mammals have highly specialized alimentary tracts that vary a little from species to species, depending on the dietary habit of the particular animal. In the broadest sense, digestion includes the events from ingestion of feed, to chemical and physical reduction to simple products, to absorption from the digestive tract, to elimination of residues by defecation. The lipids of all animals reflect, in part, the nature of the dietary fatty acids, but also the mode of digestion. Ingestive mechanisms vary substantially between animals, reflecting dietary habit, rate of eating, and anatomic structures of the head. During mastication, or chewing, saliva is added to the ingesta. Saliva serves numerous functions in aid of digestion. Digestion in the stomach involves three major aspects of gastric function: reservoir function, mechanical reduction of feed, and hydrolytic or chemical digestion.
