Grain is increasingly being processed worldwide to produce feed for animal husbandry. The changes taking place in eating habits contribute to this situation. In order to lower the energy consumption involved, less use is being made of impact stress with the help of hammer mills to reduce grain particle sizes. This is because far less energy is required when pressure and shear stresses are applied in roller mills (Fürll et al., 1996; Hoffmann et al., 2011). However, what is interesting here is whether the different kinds of stress lead to changes in the physical properties of the ground product that than need to be taken into account when dimensioning plant and equipment. As barley represents a significant component in dry compound feed formulations, studies were first conducted with this cereal.