The grounds from your Mill are already dry and full of nutritional value, which makes them a great starting material to make a chicken feed ingredient.
It also takes a lot of land, water, fertilizer, and effort to grow grains used to feed chickens. Mill turns Food Grounds into feed because it aligns with the EPA Wasted Food Scale (which recently replaced the EPA Food Recovery Hierarchy), which concludes that feeding animals is the best way of managing food scraps (after prevention and donating food that hasn’t gone bad): First, feed people. Then, feed animals.