The objective of this study was to examine the effects of feeding exogenous amylolytic and proteolytic enzymes on lactation performance of dairy cows fed freshly-ensiled corn silage-based diets. At the start of feeding, corn silage had been ensiled for 48d. It was hypothesized that the addition of amylolytic and proteolytic enzymes would improve nutrient utilization and consequently lactation performance. Thirty-six Holstein cows (18 primiparous, 18 multiparous; 132 ± 48 DIM) were used in a 9-wk randomized complete block design study. Cows were blocked by milk yield, DIM, parity, and body weight. Treatments were a 40% (DM basis) corn silage TMR with (1) no enzymes (CON), (2) amylolytic enzymes (AMY; 10 g/hd/d), and (3) amylolytic and proteolytic enzymes (AMYP; 10 g/hd/d +15 g/hd/d). Cows were housed in a freestall barn and fed with a Calan Broadbent system to determine daily individual intakes. Cows were milked 2×/d with weights recorded. Milk samples were collected for compositional analysis every 3 wk. Data were analyzed using MIXED procedure of SAS 9.4 with repeated measures and means compared using Tukey’s test. Significance was declared at P ≤ 0.05. There was a treatment × week interaction (P < 0.01) for DMI and milk yield, but no clear trends were observed. Milk yield averaged 33.6, 33.8, 33.2 kg/d; SEM = 1.21 for CON, AMY, AMYP, respectively. The dry matter intake averaged 25.4, 25.2, 24.7 kg/d; SEM = 0.73. No differences (P ≥ 0.05) were observed in feed efficiency (milk yield/DMI; 1.38, 1.38, 1.36; SEM = 0.05), yields of milk fat (1.00, 1.06, 0.93 kg/d; SEM = 0.05), protein (1.61, 1.62, 1.57 kg/d, SEM = 0.05), lactose (1.57, 16.5, 1.57 kg/d; SEM = 0.08), and SNF (2.91, 3.08, 2.88 kg/d; SEM = 0.13). There was a treatment × wk interaction (P < 0.05) for MUN (12.99, 12.64, 12.20 mg/dL; SEM = 0.62) with AMY and AMYP being slightly less in wk 9 compared with CON. Body weights and condition scores were similar among treatment with no treatment × week interactions. Under the conditions of this study, the addition of exogenous enzymes maintained lactation performance compared with CON.