Have watched cows eat many a whole ear of corn in the fields after harvest for years. No problems. They will mouth it a bit and eat it.
If I may make a suggestion- if you are looking to calm your cattle, or better yet train them, try this: buy you a few bags of sweet feed mix (something with molasses in it) and buy you a decent sized hand bell (any good feed store will have one).
Put some feed in your feed bunks. When the cows come up to eat, stand nearby and ring your bell as the eat. A few times of this, and your cows will be conditioned to associate the bell ringing with sweet feed (think Pavlov). Now your cows will come to the bell for grain, water, hay, to be worked, etc. No more chasing cows. They come to you. Been doing this for years, and it works. Watched over 40 cows come running across a 400 acre field to a bell. I can drive through the woods on ATV ringing bell and have a line of cows follow me through the woods all the way down to the catch pen at the other end of pasture. Best $50 you will spend for cattle IMO on the bell and a few sacks of feed. Nice thing too is once you have your original gals conditioned, when you add new girls, they learn by default from the original girls who take off running when they hear the bell.