The purpose of this study was to assess the effects of replacing 20% of total mixed ration (TMR) by milled olive cake (MOC), with or without adding polyethylene glycol or fibrolytic enzymes on the productive performance of Barki sheep. The first experiment compared five rations in a digestion trial: theR1 ration was a control group TMR without olive cake(OC), R2 was 20% of raw olive cake(ROC), the third was 20% of ROC with polyethylene glycol, the fourth was 20% of MOC, and the fifth was 20% of MOC with polyethylene glycol. The results showed that the use of polyethylene glycol had no significant effect, so the fourth group was the best. The second experiment was Eighteen Barki lamps aged 6 months and 29.5± 5 kg average body weight were randomly divided into three homogeneous groups (six of each). R1 ( control) , R2 were fed TMR containing 20% of MOC and the R3 fed a ration of R2 plus adding fibrolytic enzymes. The results showed that dry matter (DM) and organic matter (OM) digestibility were decreased with ration containing 20% MOC, and significant differences in CP digestibility were observed when compared to experimental groups. The different experimental rations did not affect the rumen pH values. There are no significant differences in NH3 in all groups. On the other hand, there were significant differences in total gain, average daily gain, or feed efficiency between the experimental rations and Dry matter intake increased slightly when growing lambs were fed rations R3