What Can Chickens Eat?

Actually, I should say - What should chickens be fed because I already know they can and will eat anything!

We've been in a debate recently about what to throw them from our refrigerator. I'm of the belief that everything once intended for people-consumption is a-okay, but Ted treats them like human toddlers! He's been caught pealing the brown parts off fruits and dicing large vegetables, etc.

Is old lunch meat okay? How about very wilted beet greens? Fritos chips? Lemon rinds?

I'm going to do some internet research on the topic and get back to you, but in the meantime, let me know if you have any advice.