I have also heard of this, I grew up on a farm with cows, deer chew on their cud just like cows, I believe it true to a point. If you are hunting near livestock its always to keep an eye on them if you can, cows and horses will know if something is in the field or near it. At one of my private land spots the cows will walk towards the barn away from the deer, when the deer are crossing the field early morning. I go horseback riding a lot in the summer and most of the time the horses will know if a deer or predator is around before you do.