Effect of feeding date palm tree leaves as dried or silage incubated with or without bacteria on sheep performance during pregnancy and lactation periods, and lambs performance was investigated in the current study. Forty ewes (4 years old and 49.5±2.5 kg body weight) at the beginning of pregnancy were randomly assigned into four groups (n=10 in each). The first (C) fed control ration consisted of 60% concentrate feed mixture +40% berseem hay. The second (R1) fed ration contained 60% CFM + 40% dried date palm leaves (DDPL). The third (R2) fed ration contained 60% CFM + 40% silage DPL (SDPL). The fourth (R3) fed ration contained 60% CFM + 40% silage DPL incubated with Cellulomonas cellulasea (SBDPL). Digestibility trial was done at the end of lactation period. Results revealed that SBDPL increased (P≤0.05) body weight and total gain of ewes by progressing the pregnancy and lactation, with no significant difference with control group, followed by SDPL and DDPL, respectively. C and R3 improved (P≤0.05) digestibility coefficients and nutritive value compared with R2 and R1, in addition to a significant (P≤0.01) increase of rumen fermentations, protozoa and cellulolytic bacteria counts. Also, SBDPL increased (P≤0.05) serum glucose, total proteins, albumin, globulin, urea and creatinine concentrations, which affected milk yield and lambs performance comparing with SDPL and DDPL. Feeding date palm leaves silage with addition of bacteria is better than feeding silage without addition of bacteria or dried date palm leaves and could replace hay in rations of ewes during pregnancy and lactation.