[andyjdavis]

>In the evening, they'd return to their chicken house in their pen and go to sleep.

>If you have enough vegetation around, you don't need to feed them at all.

These two things are why you frequently see free roaming chickens in villages in poor parts of the world. They don't need feeding and minimal care or supervision is required.

In a rural setting whether there is plenty of vegetation available and few predators chickens are very close to being free egg and meat producing machines as there is virtually zero time or money required from their owners.