What kind of corn is used for biofuel then? All corn is used for human consumption.
Corn intended for human consumption is segregated from feed corn from planting all the way through harvest, storage and processing.
While ethanol distillation removes the sugar from corn, it does not remove the other nutrients. You've doubtless noticed from personal experience that corn is not at all efficiently digested. Raw corn fosters a condition known as acidosis in animals when fed in amounts over about 1/2 per cent of body weight per day. This condition is avoided by feeding distillers dried grains.