Eighty steer calves were divided equally into five groups and fed barley-based all-concentrate diets with 0, 0.3, 0.8, 1.1, and 1.4% added limestone (CaCO3). Steers fed the diet with no added limestone had lower rates of gain and required more feed per unit gain than those that were fed diets with added limestone. There was a trend (P < 0.10) toward lower feed intake per day as level of limestone in the diet increased. The incidence of animals walking with a stiff gait declined as the level of limestone increased. The steers were marketed as they reached a weight of about 475 kg. Carcass measurements and grades were not affected by limestone supplementation. Digestibility of the diets was determined using sheep as experimental animals. Protein and energy digestibility increased as level of limestone supplementation was increased. The source of calcium in the diet as well as the calcium to phosphorus ratio may influence feed intake and animal performance.