The three sets of 12 Assaf lambs (4 each) feed the following diets: Control, which comprised of 15% alfalfa hay and 85% concentrate feed mixture, (CFM) (on DM basis).; (T1): Control + 2 g fibrolytic enzymes/h/day; and (T2): Control + 4 g fibrolytic enzymes/h /day. The growth experiment went on for 28 weeks. Lambs were fed diets at levels of 3.5 % DM of body weight. The weight of animals was measured weekly before feeding at 8:00 a.m. to ascertain the average daily gain (ADG). Lambs were fasted for 12 hours before butcher, weighed just before slaughter (SW) and after complete lose blood from the body. Weights of cadaver separable fat, inward and outer offals and body fats were weighted and computed as percentage of body weight at slaughtering (SW). Blood serum specimen and rumin liquor were taken at the last day of treatment immediately before butchering from jugular vein from all lambs. The fundamental outcomes outlined as follows: Feed intake and body weight: There were no significant impact between lambs regarding feed intake, primary LBW and last LBW. Carcass traits:Dressing percentages A or B were not significantly influenced by fibrolytic enzymes treatment.Cadaver cuts: Lambs fed portions with low (T1) or high level of fibrolytic enzymes (T2) significantly raised (P<0.05) weights of shoulder, loin and neck than control in the diet, but did not significantly (P>0.05) influence weights of legs, rack, brisket and flank. Low and high level of fibrolytic enzymes reduced the percent of shoulder and rack than control, but raised the percent of loin, flank and neck than control. Edible offals: Lambs fed portions supplemented with fibrolytic enzymes (low level) (T1) significantly (P<0.05) raised the weights of liver, kidney, tests and heart than control. Anyway, high level of fibrolytic enzymes significantly (P<0.05) reduced kidney, testes and heart weight than control. Total edible offals weight was sunrivalled with T1 followed by control, then T2. Non-edible parts: Lambs fed diets with high fibrolytic enzyme (T2) had higher pelt and empty gastro-intestinal part (GIP) than control group with significantly (P<0.05) differences. Notwithstanding, there were no significant differences (P>0.05) between the diverse sets relating to head, feets and GIP full. Rumen liquor: pH demonstrated insignificant (P>0.05) values by Assaf lambs fed on control, T1and T2 diets. All ruminal pH values were above 6.0. Time of sampling had a significant impact (P<0.05) on rumen pH values. Total volatile fatty acids: TVFA's concentration demonstrated higher (P<0.05) values by Assaf lambs fed fibrolytic enzymes supplemented-diets compared with Assaf lambs fed control. NH3-N demonstrated significant (P<0.05) raise by Assaf lambs fed fibrolytic enzymes supplemented-diets compared with Assaf lambs fed control. Time of sampling had a significant impact (P<0.05) on rumen NH3-N with an opposite trend of pH values. Blood components: Total protein and its fractions: Supplementing lambs diets with low level of fibrolytic enzymes (T1) significantly (P<0.05) raised total protein and globulin contents than control or high fibrolytic enzymes level (T2). Albumin content reduced with high (T2) enzymes (T2) than the control or (T1) diets. Kidney functions (urea or creatinine), Liver functions (AST or ALT) or Lipids (triglycerides and cholesterol) and glucose metabolism: Treated rations did not significantly (P>0.05) affect its levels. Economical efficiency: was raised to be the highest with high fibrolytic enzymes level and was the lowest with control. From the previous results, it could be concluded that supplementation of fibrolytic enzymes as 2 or 4g/h/d enhanced productive performance of Assaf lambs, but it was the highest with high level of fibrolytic enzymes supplementation than low fibrolytic enzymes level.