Well that can be good in some cases, but I prefer not to feed them roadkill, which can promote them to eat dead animals lying on the ground. Who knows what kind of diseases they can carry.
I wouldn't say that meat is bad for them, chickens are omnivores and they will eat frogs, mice, and dead animals that they find on the ground. I think that most people don't feed their chickens meat because they feel that it's disturbing. I don't feed my chickens meat scraps but I do let them...