The nutritive value of corn stover can be improved by an application of alkaline treatment and combining it with a protein source. The objective was to evaluate the effect of feeding a treated corn stover pelleted with either soybean meal (SBM) or dried distillers grains with solubles (DDGS) on lactation performance in dairy cows. Forty-five lactating Holstein cows (113 ± 39 DIM) were assigned to 1 of 3 diets in a randomized complete block design with a 2-wk adaptation period followed by a 10-wk experimental period. Cows were blocked by DIM and milk production. Dietary treatments were one of the following: (1) control diet with no pellets (CON), (2) treated corn stover-SBM pelleted diet (SBM Pellet), or (3) corn stover-DDGS pelleted diet (DDGS Pellet). Inclusion rate of pellets in the treatment diets was 17% of the total ration on a DM basis and pellets replaced a combination of soybean hulls (75.3%), soybean meal (20%), and limestone (4.7%). Data were analyzed using the MIXED procedure of SAS. Cows fed CON had greater DMI (30.2 vs. 27.2 and 25.4 kg/d; P < 0.001) and milk production (50.4 vs 46.5 and 45.1 kg/d; P < 0.001) compared with cows fed SBM pellet and DDGS pellet diets. Milk yield did not differ between pellet diets (P = 0.30). However, DMI was greater for cows fed the SBM pellet diet than cows fed the DDGS pellet diet (P = 0.04). Milk protein percentage was greater for cows fed CON compared with SBM and DDGS pellet diets (2.88 vs. 2.82 and 2.79; P < 0.01) and tended to have increased milk fat percentage (3.67 vs. 3.60 and 3.40; P = 0.07). Protein source added to the pellet (SBM vs. DDGS) tended to effect milk fat yield (1.67 vs. 1.55 kg/d; P = 0.07) and milk fat percentage (3.60 vs. 3.40; P = 0.06). Milk urea nitrogen was greater for cows fed CON compared with SBM and DDGS pellet diets (13.0 vs. 11.9 and 11.4 mg/dL; P < 0.001) and tended to be greater for cows fed the SBM pellet versus cows fed the DDGS pellet (P = 0.06). Overall, cows fed the CON diet had the highest performance. However, the source of protein used in the treated corn stover pellets may have an effect on lactation performance.