A cow's stomach have four chambers. The first chamber - is the Rumen, this is the large chamber, often with a rather complex shape, that helps to store the food after it is eaten. The second chamber is the Reticulum, where further fermentation occurs, but the solid food is partially regurgitated up into the mouth for a second round of chewing. The chewed cud, along with the fermented liquid, then passes straight on to the third chamber, the Omasum. The fourth and final chamber is the Abomasum, it's here the digestive glands are located, secreting acid and enzymes to break the food down, just as the stomach of any other mammal does.