The aim of this study was to evaluate the energetic feeding potential of whole-crop barley silage as related to maturation in order to determine an optimum maturity stage to harvest. Barley was harvested in transition to dough stage (TD), middle/end of dough stage (MED) and yellow ripeness (YR), and ensiled. Digestibility of dietary organic matter (OM) by sheep fed at maintenance decreased by 3.5% as a result of maturation (silage mean 67%). In contrast, voluntary intake of OM increased by 5.5% from TD to MED (diet mean 28.5 g kg−1body weight). The energetic feeding potential, calculated as intake of digestible OM, was not affected by stage of maturity. The main neutral cell wall sugars were β-glucose (23%) and xylose (12%) followed by arabinose (2%). The digestibilities of all cell wall fractions except β-glucose decreased with advancing maturity. The strongest effect was observed for mannose followed by arabinose, galactose and xylose. It is recommended to harvest barley for whole-crop silage at MED.