This study was carried out at the Animal Production Research Station of Sids to evaluate the effects of substituting 10, 20 and 30% of the concentrate feed mixture (CFM) by olive pulp cake on the nutritive values by sheep and milk production and it^'s composition of lactating buffaloes.  Digestibility trials were conducted using 12 rams to evaluate the feeding values of the experimental rations.  The control diet (R1) was containing the concentrate feed mixture (CFM), while R2, R3 and R4 contained 10, 20 and 30 % olive cake pulp, respectively on the account of CFM of R1.  Urea was added fresh at a rate of 0, 40, 80 and 130 g / head / day to equalize crude protein contents in tested rations.  Sixteen lactating buffaloes were divided into four groups and fed on the experimental rations (R1, R2, R3 and R4) for 112 days.  In both experiments, the animals were fed on 1.5, 1.0 and 1.0 % of their live body weight CFM, berseem hay and rice straw, respectively.  Crude protein (CP) content was decreased by increasing olive pulp in the ration.  Ration 4 had lower CP, but higher EE than the others.  Significant (P < 0.05) differences in digestibility of CP among treatments were recorded.  Significant ( P < 0.01 ) differences in DCP among all treatments were also recorded. The values of total DM intake (kg / head / day) and (kg DM /100 kg body weight) were increased as olive pulp portion increased in the diet.  Insignificant difference ( P > 0.05 ) was found in total DM intake among all groups of buffaloes.  Actual and 7 % fat-corrected milk yields show that the differences among treatments in milk yield were insignificant.  The results indicated significant differences (P < 0.05) among treatments in milk fat %.  The values were 6.3, 6.3, 6.6 and 6.1 kg / day for R1, R2, R3 and R4, respectively.  In the present study, there were insignificant differences among treatments for milk protein content, milk total solids (TS) and solids not fat (SNF) percentages.  Animals fed R3 (20 % olive pulp) showed the highest economical efficiency followed by R4 (30 % olive pulp) and R2 (10 % olive pulp) compared to the control diet.  The lowest feed cost / 1 kg 7 % FCM was recorded for R3 followed by R4, R2 and the control group.  It is clear that replacing up to 20 % of the CFM by olive pulp increased milk yield and economical efficiency than the control ration.