This subject comes up from time to time, but I have never known of anyone who has actually fed it to rabbits. Duckweed is rich in nutrients, but if I were going to try it for rabbits, I would feed it first to a rabbit destined for freezer camp. I'd be more comfortable feeding it to ducks, geese and chickens.
Please, please, please.... If you decide to give this a try with rabbits, would you be kind enough to let us know how it goes? It could really help with natural feeding in winter, since duckweed can be grown in tanks indoors.