The objective was to investigate if Lactobacillus buchneri (LB) could reduce Escherichia coli O157:H7 (EC) shedding by lactating dairy cows (Experiment 1) and inhibit the growth of the pathogen on and increase the aerobic stability of silage and a TMR (Experiment 2). In Experiment 1, 487 dairy cows were screened for EC counts using swab samples from the recto-anal junction. Twenty-eight infected animals were selected and blocked into low (EC count <10³ cfu/swab) and high shedders (EC count >10³ cfu/swab). Corn forage was harvested and ensiled with (Inoculated; INO) or without (Control; CON) LB inoculant and the resulting silages were mixed into separate TMR. Each TMR was offered to low or high shedder cows for 21 d. For Experiment 2, to measure aerobic stability and EC inhibition, CON and INO silages and TMRs were sampled at silo opening and aerated for 7 d after treatment with either distilled water alone or EC (5 × 10⁵ cfu/g). Treatments were arranged in a 2 × 2 factorial to evaluate main effects of fecal shedding and LB inoculation (Experiment 1) or LB and EC inoculation (Experiment 2) and the respective interactions. Silage inoculation and level of EC shedding did not affect milk production or DM intake (P > 0.10). The prevalence of EC was greater for high compared with low shedders (2.67 vs. 2.12 log cfu/swab, P < 0.01). Inoculated silage tended to reduce EC shedding from low shedders on d 7 and 21 (P = 0.13). Inoculation with LB increased (P < 0.05) silage and TMR aerobic stability (144 vs. 30.2 h and 99.2 vs. 25 h, respectively) and inhibited the growth of EC in silage (0 vs. 6.62 log cfu/swab, P < 0.01). Inoculation with LB improved silage and TMR aerobic stability, inhibited the growth of EC in aerated silage and tended to reduce EC shedding by low shedder but not high shedder cows.