Four ruminally fistulated crossbred (Brahman × native) beef cattle steers with initial body weight (BW) of 400 ± 40.2 kg were randomly assigned to a 4 × 4 Latin square design. The dietary treatments were: T1 = urea (control); T2 = soybean meal (SBM); T3 = urea CaCl2 mixture (U-Cal); T4 = urea CaSO4 mixture (U-Cas), respectively. The urea calcium mixture (UCM) products were prepared according to Cherdthong et al. (2010a) by, in brief, providing an aqueous solution (23 g CaCl2 or CaSO4 + 17 mL H2O) of CaCl2 or CaSO4 at 50 °C for 10 min and dissolving solid urea (60 g urea) in aqueous CaCl2/CaSO4 and then heating and agitating the mixture at 50 °C for 10 min prior to reducing the temperature of the solution to about 25 °C. Concentrates containing 161 to 162 g/kg of CP and 11 MJ/kg dry matter (DM) were fed at 5 g/kg of BW daily of concentrates, and rice straw was fed ad libitum allowing for 100 g/kg refusals. All steers were kept in individual pens, and clean fresh water and mineral blocks were available at all times. The experiment was 4 periods, and each lasted 21 d. During the first 14 d, all steers were fed their respective diets with ad libitum intake, whereas the last 7 d they were moved to metabolism crates for total urine and fecal collection during These days they were restricted to 900 g/kg of the previous voluntary feed intake of straw, but still supplemented with concentrate at 5 g/kg of BW daily. Table 1 shows the chemical composition of the concentrates and rice straw.