When calves are born, they start out as simple stomached animals. The change from one digestive method to another is a process that is called rumen development. The first two compartments make up one large fermentation vat, the third is an unusual-looking organ that absorbs water and minerals from digesta leaving the rumen, and the fourth is the true stomach that functions like the stomach of monogastric (people and pigs). All four of these stomachs are present at birth; however, only the abomasum is fully developed …