A study was conducted to determine porcine in vitro digestion and fermentation characteristics of the wheat and wheat millrun without or with a with xylanase and β-glucanase blend (XB, Danisco UK Ltd., Marlborough, Wiltshire, UK) that supplied 4,880 units of xylanase and 608 units of β-glucanase per kilogram of treated feedstuff in a completely randomized design. Samples were hydrolyzed in 2 steps using pepsin and pancreatin. Subsequently, residues were incubated in a buffer solution with minerals and fresh pig feces as inoculum. Gas production was measured for 72 h, and modeled to estimate kinetics of gas production. Concentration of VFA per unit weight of residue incubated or feedstuff was measured in fermented solutions. In vitro digestibility of DM (IVDDM) for wheat (77.7%) was greater (P < 0.05) than that for wheat millrun (63.2%). Feedstuff and XB interacted (P < 0.05) on IVDDM such that XB supplementation increased (P < 0.05) IVDDM for wheat, but not for wheat millrun. Total gas production of residue incubated for wheat (176.6 mL/g DM) was greater (P < 0.05) than that for wheat millrun (117.4 mL/g DM). Also, total VFA production per unit weight of residue incubated for wheat (3.12 mmol/g DM) was greater (P < 0.05) than that for wheat millrun (2.16 mmol/g DM). However, XB did not affect total gas production and total VFA production per unit weight of residue incubated. Total VFA production per unit weight of feedstuff for wheat (0.79 mmol/g DM) was lower (P < 0.05) than that for wheat millrun (0.93 mmol/g DM). Feedstuff and XB tended to interact (P = 0.096) on total VFA production per unit weight of feedstuff such the XB decreased P < 0.05) total VFA production per unit weight of feedstuff for wheat but not for wheat millrun. In conclusion, wheat was more digestible by porcine pepsin and panceatin than wheat millrun, whereas wheat millrun was more fermentable than wheat. The XB supplementation increased the digestion of wheat, but had limited effect on the digestion and fermentation of wheat millrun.