Protein starch matrix is a physical barrier to starch digestion in corn grain. The objective of this study was to evaluate 2 corns, Flint (F) and Floury (D); 2 particle sizes, grinded Fine (Fi) or Coarse (Co); application of 3 enzyme combinations, amylase (A), protease (P) and both (AP); during 3 times of ensiling (TP) at 1, 3, or 5 mo in a complete randomized design resulting in 36 treatments. Each of the 5 silos for each treatment (replicates) consisted of 1kg of corn at 35% moisture and were stored in vacuum sealed bags at environmental temperature. Enzymes used were 650 g/t of amylase and 200 g/t of protease or the combination of the 2. Samples were analyzed for in vitro degradability for 18 h and fermentation of gas production for 24 h (Ankom RFS, Ankom Tech.). Statistical analysis was performed using the MIXED procedure in SAS. Corn F had lower soluble fraction (Fs) degradability (6% of incubated, P < 0.0001) but higher degradable fraction (Fd, P = 0.02) than D (42 and 43% of incubated, respectively). Corn Co had higher indigestible fraction (Fi, 53% of incubated, P = 0.002) then Fi (51% of incubated). Enzyme P resulted in higher (P < 0.0001) Fd (43% of incubated) and AP (44% of incubated) than A (39% of incubated). Addition of AP reduced Fi portion and increased the rate of degradation (P < 0.0001) over time. Time points 3 and 5 had higher Fd (30% on TP1 vs. 50% on TP3 and 5; P = 0.002) than TP1, thus, the rate of degradation increased in the last month of ensiling (from 0.02 to 0.04; P = 0.004). Timepoint 3 had a higher (P < 0.0001) absolute pressure 37.42 psi for TP1, 42.81 psi for TP3 and 38.08 psi for TP5 and cumulative pressure 9.77 psi for TP1, 16.5 psi for TP3 and 8.92 psi for TP5 (P < 0.0001). Data from gas production were divided in 2 periods: 0–12 h and 12–24 h. Period 1 (6.17 psi) had lower (P < 0.001) gas production than period 2 (17.30 psi). In conclusion, corn ensiled and treated with enzymes for 3 mo had improved in vitro degradability than non-ensiled corn. Treated corn has great potential to improve farmer’s profitability when fed to cattle.