We are currently raising mostly Californian rabbits. They produce a good size yield in the carcass and are easy keepers so far. Originally we were keeping them in elevated hutches and feeding dry hay and alfalfa pellets. We have since started migrating them to grass. I have been watching carefully for signs of scours, and so far have not seen issues moving from dry feed to the fresh grass. I have noticed that the animals require less drinking water due to the water content of the feed. This just makes it a bit easier in the summer when the water needs of the livestock are super high.
I have seen a lot of rabbit tractors on blogs and websites, and many of them are quite elaborate in an effort to keep the rabbits from tunneling out of the bottom of the tractor. I thought I'd keep it simple. I am trying an old dog crate I had for large dogs. The bottom wire is welded in 1x3 rectangles, and the sides are the same. No open bottom and fancy wire barriers to keep the rabbits enclosed. For the most part they can reach the grass easily. They will also scratch the grass out from under the wire for easy eating. I have to say it is working great so far.
In the typical pastured livestock scenario, the manure falls to the ground to just become fertilizer for the sward. Nutrient recycling and part of my master plan to never, ever have to muck anything out.
Check out the grid pattern of daily cage movements where the rabbits have eaten the grass down. The old spot gets time to recover and regrow as the rain soaks the rabbit manure and urine back into the soil as nutrients. Fresh grass every day. You can see 7 days back in the top right corner, just half of the grid is visible, the grass is already coming back.