I have fed live/ dried worms to chickens as young as 3 days old.
When our hen, Pokey, first led her batch of chicks off the nest, I wanted to congratulate her so I gave her a mealworm, thinking she would gobble it right down (she'd just lost a third of her own body weight brooding those eggs). She immediately gave that mealworm to one of her chicks. I was horrified! I started to run to my computer to look up whether it was OK to fed a mealworm to a newly hatched chick, but then I realized Pokey probably knew what she was doing. And she did.
