When barley has been used as a supplement to straw in diets for finishing cattle the performance achieved has often been below target. A trial was made to measure whether substitution of sugar beet pulp, a fibrous source of energy, for barley in such diets would Improve performance. Forty-eight Frieslan-type steers weighing 370 kg were offered long, Spring barley straw (variety Doublet) ad libitum. The straw was either untreated or treated with ammonia. Ammonia treatment was carried out in an oven with 3% anhydrous ammonia for 21 hours. Supplementation of the straw was designed to give a daily live weight gain of 1 kg. Animals offered untreated straw received 5.5 kg per head daily of dry matter (DM) from supplementary concentrates whilst those offered ammonia-treated straw received 4.5 kg concentrate DM. Included in the concentrates was 0.23 kg DM from white-fish meal and 0.07 kg of a mineral/vitamin supplement. The animals offered untreated straw also received 0.09 kg per head daily of urea. The remainder of the concentrates consisted of either bruised barley, a mixture of equal parts of DM from bruised barley and dried molassed sugar beet pulp, or sugar beet pulp only.