Although in vitro data with mixed ruminal fluid has shown positive effects of a blend of probiotics on measures of fermentation, digestibility, and microbial profiles, there is a lack of in vivo data with mature small ruminants. Therefore, the current study evaluates the potential of a blend of probiotics (ABLB) alone or combined with Saccharomyces cerevisiae (SC) on rumen characteristics, digestibility, and blood biochemistry in sheep. Five males Saidi sheep (54.14 ± 1.67 kg body weight) were randomly allocated in a 5 × 5 Latin square design. Animals were fed basal diet or supplemented alone with 1 g/day/animal of a bacterial formula containing Lactobacillus acidophilus, Lactobacillus bulgaricus, Bacillus licheniformis, and Bifidobacterium bifidum (1:1:1:1) at two levels: 2 × 109 (ABLB2) and 4 × 109 cfu/g (ABLB4) as the 2nd and 3rd alone or combined with SC (1 gram/ animal/day) as 4th (ABLB2+SC) and 5th (ABLB4+SC) tested diets. The results show that all probiotic supplements significantly reduced (P<0.05) NH3-N concentrations and pH values at 0 and 3 hours after feeding compared to the control.