So why do deer biologists preach high protein diets... Say 16%+ to grow bigger racks? Without a doubt, all summer long and into the fall until the soybean fields around my father's turn yellow, there will be many deer pouring into them each evening to feed on the high proteins leaves. Then later after the beans have hardened, they're back in those field eating the beans that are stilling hanging or were missed when harvested... The big buck I shot last year was packed full of corn and beans.