If it were me, if their forage was good (actively-growing plants, and *lots* of bugs) all's I'd do is make sure they have a free-choice calcium source and possibly a free-choice thing of plain mixed grains (the cheap kind from the feedstore, when you walk in and say "gimme a bag o' mixed grain please", I don't mean anything fancy).
If plants are not actively growing or are getting a bit beaten down, or bugs are scarce, I'd give them layer pellets because waste is less than other forms of balanced ration. I like Free's suggestion of sprouted grains but it might be a little tricky balancing the amount you offer iwth the amount they eat... or it might not, I dunno, certainly worth trying.
Pat