rather than feeding them dry bunny food or whatever, because although it lasts long it does them no help whatsoever and it would probably be better giving them nothing
instead, you know you can get those yoghurt cvered raisans and stuff? well they are quite a nice little snack for them! mine love them! and they have tp nibble into the yoghurt so it lasts longer
also, dried pineapple chunks and pieces of dried apple that you can get from some health stores are nice aswell, but not too many as they are quite sugary
another mildly healthy thing you can add is some healthy cereals(or a tiny bit of an unhealthy one like fruit loops) but things like fruit and fibre, and granola cereals on their own and dry just put some of that in a bowl along with the rest;). And although it should be kept in the fridge, you could put some yoghurt in there ( which mine ADORE!
), the only thing is that the top kinda solidifies so its a bit less-liquid-y but underneath that it stays preserved.. also, they dont mind eating the harder bit either! And, although not advised and not on more than one occasion.. if they dont like the food its okai if they dont eat for just one night if you cant get hold of the stuff, but even fruit thats been out for a while is better than this so please try your best to get as much of this stuff as possible
Also, if you put small fruit and veggies that havent been cut up like grapes, blueberries or peas then they wont go mouldy and it still gives them their nutritious diet