Do you purchase horse tack or horse feed in Oklahoma? Do you need feed for a broodmare? In the first three months of lactation, mares can give up almost 3% of their body weight daily in milk production. For a 1,100-pound mare, that means about 24 pounds (about 3 gallons) of milk daily! This means a typical 1100 lb mare needs about 30 lbs of hay and 20 lbs of feed concentrate daily, at least double her forage when she isn’t feeding a foal.