Corn is a terrible feed for animals. The DDGS leftover after fermenting is a much better animal feedstock.
Said another way:
Feed a cow a bushel of corn and all the grass it can eat, the cow will gain 6 pounds.
Ferment the same bushel of corn and feed the cow the leftovers with all the grass it can eat, the cow gains 9 pounds.
I’m not a big-oil conspiracist or a tree hugger, but most anti-ethanol arguments are not based in fact.