The typical dairy ration contains a mixture of forages and concentrates. The concentrate portion contains carbohydrate sources such as corn and a mixture of protein ingredients, along with minerals and vitamins. Nutritionists try to formulate a protein source to maximize milk production. In general, a protein supplement is the most expensive ingredient in a ration. It is important to understand how the forage program and rumen function help meet the protein needs of the dairy cow. There are two types of feed proteins. One type of protein is utilized by rumen microorganisms and is termed degradable intake protein (DIP). The other type of feed protein passes through the rumen without being degraded and is termed undegradable intake protein (UIP). Dairy cows require both DIP and UIP.