The worms can eat small particles of feed, i.e. broken down organic matter, Purina Worm Chow
... At the same time there is a benefit of the microbes as per breaking down the larger particles as well as certain microbes generated at certain temperatures which appears to help in growth rates and reproduction when generated in certain feed mixes.
I have been playing with this for a while and have another batch we are keeping an eye on at the moment.
As for the rabbit manure, if it has been separated from the rabbit urine, the pH should be neutral while the protein level can be anywhere from approximately 12 to 18 percent. Variances occur in rabbit manure since they only process about 25% of the food they ingest hence what they are fed will cause a difference in the end result.
In the Earthwormponics we do feed the worms a mixture of mainly shredded dry rabbit manure.