The objectives of this experiment were to evaluate the effect of a single oral drench of Megasphaera elsdenii NCIMB 41125 (Lactipro Advance, MS Biotec, Wamego KS) on milk production and feed intake of dairy cows upon an abrupt change to a high-starch diet immediately post-calving. Thirty-six multiparous Holstein cows were blocked by their predicted 305ME and assigned randomly to one of 2 treatments: (1) 100 mL drench of viable M. elsdenii (LACT; 2 × 10⁸ cfu/mL) 72 h postpartum, and (2) a drench of 100 mL of autoclaved product as control (CON) administered at the same time as LACT. Both treatment groups were offered a fresh-cow diet formulated to contain 29.6% starch and 46.2% NFC (DM basis) via individual feeding gates. Daily milk production and feed intake as well as weekly BW, BCS, and milk components were recorded through 90 DIM. Data were analyzed using repeated measures in the MIXED procedure of SAS. On average, cows drenched with LACT consumed 6% less DM (P = 0.04) compared with control cows (23.5 vs 25.1 ± 0.51 kg/d, respectively). This decreased feed intake was not associated with differences in average milk production between LACT and CON (49.27 vs 48.26 ± 1.31 kg/d, respectively; P = 0.57). Consequently, cows drenched with LACT tended to produce milk with greater efficiency (P = 0.07); BW and BCS were similar for both treatments (P ≥ 0.36; 668 ± 13 kg and 3.29 ± 0.04, respectively). Control cows tended to have increased (P = 0.10) concentration of milk fat relative to LACT cows. This trend resulted in similar ECM and FCM production efficiency for both treatments (P ≥ 0.29). Yield of milk fat and protein were similar (P ≥ 0.24) for both treatments averaging 1.90 ± 0.06 kg/d and 1.47 ± 0.04 kg/d, respectively. These results demonstrate that a single, postpartum administration of a drench containing Megasphaera elsdenii NCIMB 41125 decreased DMI and tended to improve milk production efficiency in early-lactation cows while maintaining yield of milk and milk components.