So I have read that chickens can eat pretty much anything that humans can eat. I have been giving them a little bit of hamburger fat mixed with threaded bread oats and or cracked corn. How much fat is too much?
well I wouldn't give them too much fat because it will lead to weight gain and then you will have issues, if they are meat chickens they will get too big too fast and health issues will arise if they are egg layers they will become lazy due to excess weight, plus too much is not healthy because they will be missing out on some much needed nutrients. As a treat I don't see a big issue with it.
I give mine treats all the time, but its mostly greens and BOSS, they get scratch once per day and free choice layer and water. I emphasize the greens though cause its healthy for them.