The study was performed to evaluate the effect of partial or complete replacement of maize silage (MS) with orange by-product silage (OBPS) on feed intake, nutritive value, digestibility, milk production and composition, of Barki ewes. Thirty-two Barki ewes (3-5 years old and live body weight 41±0.29kg) were divided into three equal groups; the 1st group (control) was fed concentrate mixture and MS (G1), the 2nd and 3rd groups were fed the concentrate mixture and replaced MS with 50% OBPS (G2) or 100% OBPS (G3). The forage concentrate ratio in all groups was 50%:50%. The results indicated that the lowest dry matter intake (DMI, g/h/d) was recorded in control group followed by G2, while G3 recorded the highest value. The NH3-N concentration was significantly decreased (P<0.05) due to partial replacement of MS by OBPS. Also, an opposite relationship was a served between NH3-N concentration values and the microbial protein content values, over all dietary treatments. While concentrations of total volatile fatty acids (TVF's) were significantly increased (P<0.05) with G2 and G3 compared to G1. The replacement of maize silage by orange by-products silage at 50% or 100% in G2 and G3, respectively showed significanteffect on all nutrient digestibility coefficients compared with G1. The overall daily milk yield, and milk constituents percentage of fat, protein, lactose, solids not-fat (SNF) and total solids were improved (P<0.05) due to partial or total substitution of maize silage by OBPS compared to the control group. The average body weight of lambs at the 10th week of age was 13.31, 14.58, and 14.94 kg for the G1, G2, and G3, respectively. The measured blood parameters show slight differences except cholesterol and triglyceride that were significantly decreased with G2 and G3 vs. G1. It can be concluded from the data of the current study that the OBPS can be fed to ewes and have positive effects on the feed conversion, milk production, and performance of newborn lambs without any adverse on blood parameters this is of particular value in the north-western coast where sheep are fed on reduced roughage feed due to lack conventional sources of roughage resulting in increased cost of feeding compared to economic return from harboring small ruminants.