A replacement heifer will consume 40 pounds of milk replacer, 90 pounds of calf starter, 40 bushels of corn, 250 pounds of protein supplement, 100 pounds of mineral/salt, and 6 tons of forage dry matter from birth to calving. A lactating cow (producing 20,000 pounds of milk) will consume EACH year 5.7 tons of forage dry matter, 106 bushels of corn, 1,400 pounds of protein supplement, and 225 pounds of mineral/salt. If the cow stays in the herd for three lactations, multiply these last numbers by 3. One pound of dry matter equals 3 pounds of corn silage, 2 pounds of haylage, OR 1.1 pounds of hay.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET