The omasum is one of the four compartments of a ruminant's stomach, located between the reticulum and the abomasum. It plays a crucial role in the digestion process by absorbing water and nutrients from the partially digested food, known as cud. The omasum has many folds, which increase its surface area and enhance its ability to absorb. In ruminants like cows and sheep, the omasum helps to further break down food before it moves to the abomasum, where enzymatic digestion occurs. This compartment is essential for efficient nutrient absorption, contributing to the overall digestive health of these animals.