As of December 2015, a detailed cow anatomy diagram with illustrations from Spurgeon's Color Atlas of Large Animal Anatomy is available from Shopanatomical.com. University of Kentucky's Agripedia website, the Animal Corner blog, and the University of Minnesota Dairy Extension all offer free online bovine anatomy diagrams.
Cows are herbivores, meaning they eat only plant materials. Cows are ruminant animals that have a four digestive parts to their stomach and produce cud. The largest part, the rumen, holds up to 50 gallons of partially digested food. Good bacteria in the rumen helps digest the food and absorb useful fatty acids. The reticulum is a honeycomb pouch-like structure that collects difficult to digest or indigestible items.
The omasum is the filter of the digestive system and is used to absorb water. These first three parts also help digest the cow's cud that is regurgitated for addition chewing. The abomasum is most like a human or other non-ruminant's stomach. Food is broken down by digestive enzymes, and essential nutrients are passed into the bloodstream. Any waste from this process is passed to the intestines for elimination.