In the beef cattle diet, common roughages include hay, silage and grass. Silage is a crop that has been preserved in a moist, succulent condition by partial fermentation in a tight container (silo) above or below ground. The majority of the food cattle eat comes from this type of feedstuffs.
Birds (some dinosaurs) and mammals have a four-chambered heart. The ventricle is divided by a septum into two compartments completely separating oxygenated from deoxygenated blood and delivering the maximum amount of oxygen to the head and body at the most efficient pressure.
The atria and the ventricles are separated by valves, which allow the blood to flow through the heart in one direction and prevent back flow of blood. The wall of the heart is made up of three layers. The outer layer is called the epicardium. The middle layer is the actual heart muscle and is called the myocardium. The inner layer of the heart is called the endocardium. The heart is contained within a sac called the pericardium. The sole purpose of the heart is to pump blood to and from the rest of the body.