Cereal grains are rich in starch and their content depends on plant variety, weather conditions, and agricultural practices. Adult cows have limited ability to chew cereal grains; it is essential then to break down the seed pericarp by means of chemical or physical treatments to improve its digestibility in the digestive tract.
Grain processing can be divided in two: non-thermal processes such as roller and hammer mills, and thermal processes including dry processing (roasting, etc.) and wet processing (autoclave, steam laminate etc.).