Nutritive value of crop residues may be improved through prestorage treatment with Ca(OH)₂. The objective of this experiment was to determine the effect of maximal substitution of either haylage or corn silage with Ca(OH)₂-treated corn stover on feed intake, milk production and milk composition in lactating dairy cows. Corn stover was processed by chopping, rehydrating, and treating with 6.6% Ca(OH)₂ (DM basis), and stored in bag silos. Six mid-lactation multiparous Holstein cows were assigned to one of 2 groups and randomized within group to a Latin Square design to receive a TMR without any added Ca(OH)₂-treated stover (CON), a TMR where Ca(OH)₂-stover replaced alfalfa haylage at 15% of the diet (HYLGsub), or a TMR where Ca(OH)₂-stover replaced corn silage at 19% of the diet DM (CSsub). Diets were evaluated in a 3 × 3 replicated Latin square consisting of 3 21-d periods. Cows were individually fed in tie stalls. The first 14 d of each period were used for diet adaptation followed by 7 d of data collection. Milk production was not different (P = 0.77) among treatments. DMI was reduced (P < 0.05) for HYLGsub and CSsub diets when compared with CON (24.5, 21.8, 20.6 ± 1.0 kg/d for CON, HYLGsub, and CSsub, respectively). Milk fat percent was decreased (P < 0.05) with inclusion of Ca(OH)₂-treated corn stover (3.92, 3.66, 3.69 ± 0.15%, CON, HYLGsub, and CSsub, respectively) and milk fat yield tended to decrease (P = 0.09). Milk protein percentage was reduced (P < 0.05) by Ca(OH)₂-treated corn stover inclusion (3.27, 3.16, and 3.11 ± 0.06% for CON, HYLGsub, and CSsub, respectively) but milk protein yield was unaffected (P = 0.32). Energy-corrected milk production per unit of DMI (kg/kg) was greater (P < 0.05) for cows fed diets containing Ca(OH)₂-treated corn stover (1.12, 1.26, and 1.30 ± 0.05 CON, HYLGsub, and CSsub, respectively). Results show that Ca(OH)₂-treated corn stover can replace haycrop forages or up to 31% of the corn silage in diets for dairy cows without negatively impacting milk production while simultaneously improving the efficiency of conversion of feed to milk.