mine free range. while this gives them lots of bugs and everything else, i also find that since they get so much excercise they don't mind some food offered. the goats give good chase if in the mood.
i feed pretty much any kind of leftover. i dont' differentiate. sort of slopping a hog. it just all goes together and then they pick out what they want. a typical day might be leftover oatmeal, old grapes, vegetable peelings and leftover baked potatos. if it's in the summer, i might not feed anything at all for several days or even a week. they stick around though and sleep in the tree at night. so i guess they are happy critters.
in the fall and winter like now, i add in feed. i am trying to grow grasshoppers this year in a tub and we'll see how it works. we'll see. i think they would love mid winter hoppers. i just caught ones that were mating and tossed them in with pulled weeds and such. so far they are all still alive. dont' know if they will actually have the babies in there though.