Two experiments were conducted to assess the impact of adding an inoculant on corn silage (CS) aerobic stability and performance of dairy cows. A total of 166,880 kg of whole corn plant (36.5% DM) were harvested from the same field on the same day and ensiled in 2 adjacent bunker silos. One silage (81,240 kg) remained untreated (CTR), and the other (85,560 kg, INL) was treated with 300,000 cfu/g of fresh matter, targeting, for every gram of CS, 150,000 cfu of Lactobacillus hilgardii CNCM I-4785 and 150,000 cfu of Lactobacillus buchneri NCIMB 40788. Inoculation rate was 100 mL of water/ton. In Experiment 1, at silo opening (300 d after ensiling) and fortnightly for 60 d, 2 samples of 500 g were taken to determine aerobic stability in quadruplicates by placing 3.2 ± 0.21 kg of CS in insulated plastic boxes kept at room temperature for 96 h and electronically monitoring temperature continuously. Counts of yeast, molds, and lactic acid bacteria (LAB) were also performed at these time points. In Experiment 2, 60 cows (597 ± 67 kg of BW; 127 ± 41 DIM, producing 35.3 ± 8.01 kg of milk/d) were randomly allocated to a control TMR (untreated silage) or to an identical TMR (15.5% CP, 35.0% NDF, 38.2% CS, in a DM basis) containing CS inoculated as described above for 8 wk. Individual intake, milk production and composition were monitored daily. Data were analyzed using a mixed-effects model including the effect of box (Exp. 1) or cow (Exp. 2), treatment, and their 2-way interaction, with time as a repeated measure. In Exp. 1, counts of LAB, molds, and yeast were lower (P < 0.01) in INL (69 cfu/g, 68 × 10³ cfu/g, 131 × 10³ cfu/g, respectively) than in CTR (307 cfu/g, 212 × 10³ cfu/g, 996 × 10³ cfu/g, respectively) at 96 h of aerobic exposure, and time to reach instability (i.e., 3°C above ambient temperature) was shorter (P < 0.01) in CTR (29.8 ± 3.4 h) than in INL (44.8 ± 3.4 h). In Exp. 2, there were no differences in DMI, yield, or milk composition, but feed efficiency was greater in INL than in CTR cows during wk 7 and 8 of study. It is concluded that inoculating CS with L. hilgardii and L. buchneri improves aerobic stability of CS and feed efficiency of dairy cows over time.