Note that a byproduct of ethanol production is distillers grains[1] which are used as an animal feed. Also worth noting that the percentage of corn used for direct human consumption has stayed at around 10-20% before, during, and after the ramp up in ethanol production:

Ethanol + animal feed chart: https://i.imgur.com/1QqPTje.png

Ethanol production chart: https://i.imgur.com/3wwzkIi.png

[1] https://en.wikipedia.org/wiki/Distillers_grains