Cows are ruminants. During a day they spend the same amount of time eating (8 hours) as ruminating (to regurgitate partially digested food to be able to chew it over again) (8 hours). The rumination can only happen if the feed to be re-chewed is rather fiber-like. In the ideal situation, a major part of the feed intake is made up of fibers or fodder. However, the fodder is usually not sufficient for milk cows of which the need for protein is very important. It is therefore necessary to give them other feed that contributes to protein intake (peas, rape seed cakes, or soy for example). These additions of concentrated feed (for example in granules) can represent 10-25% of their feed.