Agro-waste from olive trees (OTB) which is not properly utilized and left it without treatment may lead to major social, environmental and economic problems. Such wastes can be biologically treated to increase their nutritive values and be utilized as ruminant alternative feeds. Investigate if their synergism between live yeast culture and Exogenous fibrolytic Enzymes (EFE) and impact of each of them or their mixture on OTB digestibility, nutritional values, nitrogen utilization and some ruminal fermentation are the main objectives of this study. Damascus goat bucks were randomly assigned into five groups of three animals each using complete random design. Goats were fed, 70% concentrate feed mixture (CFM)+ 30% berseem hay (control group), 70% CFM+ untreated olive trees by-product as a replacer for berseem hay (R1), 70% CFM+30% OTB treated with EFE (R2), 70% CFM+30% OTB treated with live yeast culture (R3) and 70% CFM+30% OTB treated with a mixture of EFE and live yeast culture (R4). Synergism was noted between live yeast culture and exogenous fibrolytic Enzymes (EFE) on the tested parameters. Results indicated that addition either as live yeast culture or exogenous fibrolytic enzymes increased (P<0.05) the digestibility of all nutrients which were reflected on the nutritive values (as TDN and DCP) of olive trees byproducts. Addition of live yeast culture or exogenous fibrolytic enzymes reduced ammonia-N and increased both TVFA's. Inclusion of biologically treated olive tree by products (OTB) in Damascus bucks rations improved nutritive value and ruminal activity.