Throw away the outer layers. Corn is raised with a ton of pesticides, and I think all that has to be taken off. But once you've gotten rid of the outer layer or two, the rest should be OK. That's what I always did for my pigs.
I've grown corn myself in my garden, so I know it is 100% pesticide free. When that is the case you can feed literally all of the corn plant except the corn kernels themselves. If that is not the case I agree with erring on the side of caution and tossing any of the outer bits that may have been sprayed.