Take a look at the link below.

Here is a link that might be useful: Barefoot's Rabbitry & Worm Farm

very good site. Found the information very interesting. I had 2 rabits as a kid, and they can produce alot of pellets.

Ya know if you put the bed somewhere else and put a sloped piece of screen wire under the rabbits to let the urine go through and make the pellets slide down to your collection bucket to put in the beds as you need them. Might be a lot easier to work on the beds.