Probiotics (PBT) may improve diet digestibility and lactation performance of dairy cows. This experiment evaluated the effect of a liquid supplement containing a blend of viable lactic acid bacteria, spore forming bacteria, and yeast (S. cerevisiae) cultured in consortium (Global Saúde, Brazil/SCD Probiotics, USA) on digestion, intake, and lactation performance of dairy cows. Twenty-six Holstein cows (185 ± 141 DIM) were individually fed a standard TMR for 14 d and treatments control or PBT (3.5 mL/kg of TMR DM) for 56 d, in a covariate adjusted randomized block design with repeated measures over time. The PBT increased DMI (23.5 vs 22.5 kg/d. P < 0.01, SEM 0.37) and tended to increase the yields of milk (30.0 vs 29.4 kg/d. P = 0.06, SEM 0.50) and lactose (+ 60 g/d. P = 0.09). Energy-corrected milk to DMI ratio was reduced by PBT (1.25 vs 1.31. P = 0.02, SEM 0.033). Milk solids concentration and yield did not differ (P ≥ 0.28). Cows fed PBT tended to have higher BCS (3.02 vs 2.91. P = 0.08, SEM 0.039), but BW did not differ (641 kg. P = 0.27). The PBT tended to reduce the total-tract digestibility of the non-fibrous OM (81.2 vs 84.1%. P = 0.08, SEM 1.11) whereas starch (90.7%) and NDF (48.4%) digestibilities did not differ (P ≥ 0.20). Molar proportion of butyrate in ruminal fluid tended to be reduced by PBT (9.4 vs 10.4%, P = 0.06, SEM 0.40) as well as total protozoa concentration (P = 0.10). The acetate to propionate ratio (3.1. P = 0.89) and the ruminal microbial yield estimated by the daily urinary allantoin excretion (P = 0.21) did not differ. The PBT reduced the proportion of daily intake in the morning (35.1 vs 40.4%. P = 0.02, SEM 1.52) and increased the proportion in the afternoon (45.9 vs 41.9%. P = 0.03, 1.23). Rumination and ingestion behaviors did not differ (P ≥ 0.16). The PBT reduced blood urea-N at 0900 h (P = 0.01) and tended to reduce at 1630 h (P = 0.06) and 2300 h (P = 0.09), but did not affect milk urea-N (18.6 mg/dL, P = 0.47, SEM 0.44). The PBT induced a greater increase in DMI than in milk yield, decreasing feed efficiency, and had effects on digestibility and ruminal fermentation profile.