Corn stalks treated with calcium oxide CaO showed no change in in vitro dry matter digestibility (IVDMD) at 3 or 7 days after treatment, but a small increase of 2 units in IVDMD at 14 days after treatment. Corn stalks and corn silage mixed had no change 3 days after treatment but a 7unit IVDMD increase by day 7 and a 1 unit increase at day 14. Corn silage alone had no change at day 3 or 7 but at day 14 there was a small 2 unit increase in IVDMD. Cornstalks ground to a smaller particle size and treated with calcium oxide stalks increased 5 units on average in IVDMD. There was considerable variation in the treated samples IVDMD.