Intestinal "normalization" of germ-free rabbits with rabbit caecal microflora: effect of dosing regimens.

Hysterectomy-derived germ-free (GF) rabbits were given strictly anaerobic microflora obtained from the caecum of an antibiotic-decontaminated conventional rabbit. One group was given the caecal flora diluted in doe's milk. The second group received caecal flora without doe's milk and administration of the flora was repeated when the animals were given pelleted diet. Body weight and intestinal parameters determined in the two groups of rabbits were compared with values in rabbits conventionally raised with the doe. In GF rabbits given caecal flora, the values for most intestinal parameters were similar to values recorded in conventional animals. However colonization resistance to Escherichia coli was limited in GF rabbits given caecal flora diluted in doe's milk and severely impaired in GF rabbits given caecal flora without doe's milk, although relative caecal weight was normal. It is concluded that enteric microfloras should be preferably incorporated in doe's milk when dosed to GF rabbits to obtain acceptable gastrointestinal "normalization".