Liveweight responses to two levels of supplementary feeding were compared in young cattle grazing barley stubble or fed baled material in pens. Over the 58 d of the experiment, unsupplemented animals in pens lost 0.5 kg/d, those receiving the low energy-mineral supplement maintained their initial weight, and those receiving a moderate energy-mineral supplement gained 0.3 kg/d. In contrast, cattle grazing stubble did not show any liveweight response to supplementation, all three treatments gaining at 0.6-0.7 kg/d. Grazing cattle were apparently capable of selecting a diet of much higher quality than the leaf and stem material on offer. The results emphasize the need for caution in extrapolating, to the grazing animal, results obtained in pen-feeding evaluation of heterogenous materials such as crop residues.