The key to adequate dairy cow feeding is the inclusion of feedstuffs in the diet that complement each other. Protein and energy are the most expensive macronutrients, and optimizing their metabolism is very important to improve income over feed costs. Field pea (Pisum sativum) is a crop used in the human food chain, commonly grown in the US northern great plains and Canada.. Their relatively high crude protein (avg. 21.0%) and starch (avg. 44.9%) concentrations makes them then an attractive ingredient in cattle diets. Most of their protein however is soluble protein which needs to be adequately balanced to sustain acceptable dry matter (DM) intake, milk yield, and N utilization by lactating dairy cows.