This study was designed to investigate the effect of garlic powder (GAP) or cumin powder (CUP) supplementation in growing lambs ration on nutrients digestibility, rumen liquor parameters, blood constituents and growth performance,. Eighteen of growing Barki lambs (averaged 5-6 months of age and weighted 27.5 ± 0.90 kg) were divided into three equal groups (6 animals each) in a feeding trial lasted 100 days. Animals were fed on basal diet (control) or supplemented with 2% GAP (T1) or CUP (T2) of the concentrate feed mixture. The results showed that apparent digestibility of all nutrients and nutritive values as total digestible nutrients (TDN) and digestible crude protein (DCP) were significantly (P<0.05) higher for lambs fed rations of GAP or CUP compared with those fed the control ration. Ruminal ammonia nitrogen (NH3-N) was increased (P<0.05) for lambs fed rations GAP or CUP compared with those fed the control, however ruminal pH and TVFA's were comparable among the experimental treatments. The values of N balances and dietary N utilization were increased (P<0.05) for lambs fed GAP supplemented ration compared with those fed control or CUP-supplemented diet. Meanwhile Average daily gain and feed conversion were higher (P<0.05) for lambs fed GAP or CUP than those fed control ration. Dry matter intake was comparable among the experimental treatments. There were no significant differences in plasma albumin and cholesterol concentrations among treatments, while plasma concentrations of total protein, globulin and total antioxidant capacity were higher (P<0.05) for lambs fed GAP or CUP than those fed control ration. Plasma triglycerides concentrations was higher (P<0.05) for lambs fed CUP than those fed GAP or control. Plasma malonaldhyed (MDA) was decreased (P<0.05) for lambs fed rations of GAP or CUP than those fed control ration. There was a decrease (P<0.05) in plasma concentrations of HDL with feeding CUP ration and levels of LDL with feeding GAP compared to feeding the control ration. This study showed that dietary supplementation of either garlic or cumin powder at 2 % significantly improved nutrients digestibility and growth performance in growing lambs, without any adverse effect on rumen fermentation.