The most important factors for maintaining a healthy rabbit herd are cleanliness, good ventilation, close observation, and protection from draught, sun and rain.
Rabbits are susceptible to several diseases that reduce production to unprofitable levels.
One of the worst culprits is coccidose - small parasites. These parasites are common in rabbit intestines and can under some circumstances attack the intestines. Nobody seems to know exactly why, but it may be stress-related. Coccidose is spread with manure, unclean bedding and possibly with dust from dry manure. Liver coccidose is caused by Eimera Steidae and is normally fatal by the time you discover it.