The abomasum is the fourth stomach compartment in ruminant animals, such as cows, sheep, and goats. It is often referred to as the "true stomach" because it functions similarly to the stomach in non-ruminant animals, where digestion of food occurs through the action of enzymes and acids. Located after the rumen, reticulum, and omasum, the abomasum plays a crucial role in breaking down proteins and absorbing nutrients. It secretes digestive enzymes, including pepsin, and hydrochloric acid, which help in the digestion of complex food materials, allowing the animal to utilize the nutrients effectively.