Abstract: Three mature male ruminally cannulated sheep were fed on 90% of their ad libitum intake during successive metabolism trials. The results showed that N-balance (g/day), TDN% and DCP% were significantly higher when RS ration was supplemented with 2.5% SBM + 1.5% U than that supplemented with 7.5% SBM + 0.5% U. DCP% and N-balance were significantly lower when MS ration supplemented with 2.5% SBM + 1.5% U than other supplements, but digestibility of NFE, cellulose, TDN% of the ratio of NFC intake to DCP intake were significantly higher with (7.5% SBM + 0.5% U) or (2.5% SBM + 1.5% U) than (5% SBM + 1% U) supplementation. Feeding MS rations resulted in increasing (P<0.01) NFE digestibility and TDN% when supplemented with (7.5% SBM + 0.5% U) or (2.5% SBM + 1.5% U), while the digestibilities of CF, ADF and cellulose decreased when MS ration was supplemented with (5% SBM + 1% U). Moreover, a positive and highly significant correlation coefficient (r=0.610, n=18; ) was obtained between NFC and DCP intake. The In situ DM, NDF and ADF disappearance values of MS were higher than those of RS, while the DM disappearance of MS was higher when MS ration was supplemented with (5% SBM + 1% U) than the other supplements. The potential degradability (a+b) of ADF of RS was higher when RS ration was supplemented with (7.5 SBM + 0.5%U) or (2.5% SBM + 1.5% U) than that of 5% SBM + 1.0% U) being 58.47, 54.86 and 41.59%, respectively. The potential degradability (a+b) of ADF of MS was higher when MS ration was supplemented with (2.5% SBM + 1.5% U) than that of (5% SBM + 1.0% U) or (7.5% SBM + 0.5% U), being 63.83, 51.14 and 49.77, respectively. The mean rumen pH was decreased when MS ration was supplemented with (5% SBM + 1% U) than those of the other rations. While NH3-N concentration decreased when MS ration was supplemented with (7.5% SBM + 0.5% U) or (5% SBM + 1% U) and when RS ration was supplemented with (7.5% SBM + 0.5% U). The total volatile fatty acids (VFA) concentration was higher for supplemented MS rations than that of RS rations, while it was decreased when MS ration was supplemented with (2.5% SBM + 1.5% U) than that of (7.5% SBM + 0.5% U) or (5% SBM + 1% U).