Watch a broody hen take her chicks out of the nest. They are just a few days old. They are playing in dirt. They are walking and dust bathing in dirt. They are eating dirt, bugs, tender grass and weed shoots, scratch, treats given to all the big chickens that they may have missed.....
She's not peeling apples and coring them, or checking bugs for bacteria before she'll let them have one, or examining shoots before they chow down. They eat their chick food, and whatever else she's pecking at on the ground. So that's what I do. Mine are brooded outdoors in the run in full sight of the adults. They get used to seeing the chicks everyday, and the chicks learn to be chickens by watching them. Which chicks get pasty butt - chicks raised by a broody hen or those raised artificially in a brooder? Sure, chicks being cared for by a mother hen sometimes get sick and they sometimes die. It stinks. But sometimes we do them a great disservice by delaying their growing up. They are less likely to gorge on snacks raised as naturally as possible as they do when we toss those same treats into the brooder. Out there, they peck and scratch and if they find something that looks interesting, they try it, unlike in a brooder where they get a pile of this or a bowl of that set in front of them.
I think we overthink it too much, fret too much.