A chicken will try to eat just about anything that lays on the ground, glass, metal, grain, bugs and worms, excrement from other chickens, or their own, but to eat a cob, well, they have to be very hungry and better if it's ground up for them.
Oh yes, they do not get much food value from the cob, so it has to supplemented with other foods.
I have no idea why some idiot chose to thumbs down this answer, but if you read and understand the question, which I doubt, the Asker stated he or she was to cut the corn from the cob and freeze the kernels, well, fyi, when cutting corn from the cob there is still a very small amount of kernel left on the cob, and having grown hundreds of chickens during the great depression I can attest to the fact the chickens will indeed peck and eat not only the small amount of corn left on the cob, but also some of the cob itself.