This study compared the effects of feeding a proprietary blend of heat-treated canola and soybean meal (AminoMax; Afgritech LLC; Watertown, NY) or heat-treated soybean meal (AminoPlus; Ag Processing Inc.; Omaha, NE) on lactational performance of dairy cows. Forty-two lactating Holstein dairy cows (21 per treatment) averaging 866 ± 98 kg of BW and 146 ± 30 DIM at study initiation were used in a randomized complete block design with a 2-wk covariate period followed by an 8-wk treatment period. Treatments were diets containing (DM basis) 7.7% AminoMax or AminoPlus. Diets also contained 19.3% conventional corn silage, 19.3% brown midrib corn silage, 14.0% hay crop silage, and 39.7% concentrate mix (excluding AminoMax or AminoPlus). Both diets contained 15.7% CP, 30.9% NDF, and 25.4% starch. Dry matter intake and milk yield were collected daily and milk composition was determined over 3 milkings once per week. Cow served as the experimental unit. Data from the last 7 d of the covariate period were used as a covariate adjustment. Data were analyzed by ANOVA using the MIXED procedure of SAS containing model effects of covariate, treatment, time, and treatment × time. Dry matter intake (27.4 ± 0.2 kg/d), solids-corrected milk (SCM) yield (43.8 ± 0.8 kg/d), milk fat yield (1.76 ± 0.04 kg/d), and milk true protein yield (1.39 ± 0.02 kg/d) were unaffected by diet (P > 0.10). Milk lactose yield tended to increase (2.14 versus 2.06 ± 0.03 kg/d; P = 0.09) for cows fed AminoPlus. Milk urea N concentration was decreased for cows fed AminoMax (11.4 vs. 9.6 ± 0.2 mg/dL; P < 0.01). Efficiency of SCM production (SCM/DMI; 1.59 ± 0.02 kg/kg) and N efficiency (0.322 ± 0.005 kg/kg) were unaffected (P > 0.10) by diet. In conclusion, lactational performance did not differ between the products, but N utilization appeared to be improved for cows fed AminoMax.