A series of experiments in Canada and the US, funded through the Canola Council of Canada resulted in a number of publications showing a higher rumen escape protein and lactational performance of dairy cows fed canola vs. solvent-extracted soybean meal. Rumen escape protein is critical for supplying amino acids for milk production, particularly for high-producing dairy cows. Comparison of canola meal to solvent-extracted soybean meal, however, puts soybean meal in a disadvantage because the canola seeds are already mechanically processed to decrease their oil content down to around 18%, before the remaining oil can be solvent extracted. Thus, animal production effects of canola meal CANNOT be compared to solvent-extracted soybean meal; the proper comparison is with extruded soybean meal, which is also undergoing mechanical oil extraction, thus increasing its escape protein. Our previous work, funded by the PA Soybean Board, has shown that extruded soybean meal can be comparable to canola meal in terms of milk production and components. Our data have shown that the supply of metabolizable protein was increased by the extruded soybean meal but that additional protein was not utilized for production purposes because of already high overall supply of protein with the basal diet. Thus, we propose that a diet that is slightly below the metabolizable protein requirements of the cows would benefit from the increased supply of escape protein from extruded soybean meal, when compared with canola meal. We propose to conduct a large, 10-wk (including 2 wk covariate period) production type experiment with 48 lactating Holstein cows in our free-stall facility, which is equipped with Calan gates for continuous monitoring of feed intake. We will have 2 treatments: (1) canola meal (control) and (2) extruded soybean meal. Both meals will be offered at 12 to 13% of feed dry matter intake. Dietary crude protein will be adjusted to 15% (dry matter basis), which will likely be about 5-10% below cows’ metabolizable protein requirements. Both diets will supply similar amounts (on a metabolizable protein basis) lysine, methionine, and histidine. We will monitor feed intake, milk production and composition (including milk fatty acids), body weight change (which was not possible in our previous work with extruded soybean meal), and plasma amino acid profiles. Soybean growers will benefit from the project because we intend to demonstrate greater supply of metabolizable protein and increased cow productivity with extruded soybean meal vs. canola meal, which will expand the market for soybeans and soybean meal among dairy producers.