I wouldn't FF their feed as they have specialized bowels that ferment it for them and they also re-eat some of their pellets to further digest the matter there. I would add mother ACV to the water...it really seems to add to overall health and immune system function.
Unlike Hellbender, I've given veggie scraps and grass clippings to my rabbits without any difficulty at all...no death...nothing detrimental to the health at all. My rabbits all seemed to be particularly healthy and no unexplained deaths of any rabbits that weren't kits that had just been born and had failure to thrive, but not many of those. Any sudden change in diet can cause some temporary diarrhea, so go low and slow on feed changes.
There are people who are successfully raising rabbits on a more natural diet than formulated feeds, so I know it can be done. I'd like to try alternative feed myself if I get back into rabbits, without such a dependence on formulated feeds. Mineral wheels can be provided and even loose mineral mixes can be used to balance nutrition. I think it's worth a shot to explore different avenues than accepted nutritional guidelines on a bag. That's the whole nature of this thread, actually...that thinking out of the box of what is accepted wisdom to try and get a better feed option, a cheaper feed option. Most of my chicken's dietary intake is out on the meadow and I'd like to glean such things for the rabbits, as well as putting them on pasture in a tractor. It's fun to experiment on these things to see how closely you can get the animals to a more natural diet.
Hey, folks....it's snowing cats and dogs here and it's very pretty!
Mounting up very quickly so the power may go out today due to heavy snows on top of soaking wet soils...causes trees to uproot onto power lines here. Everyone out in this deluge of snow, be careful, slow down, gear down, keep your foot off that brake!