Development of the rumen digestive functions in lambs placed in a sterile isolator a few days after birth

: The development of the rumen digestive functions was studied in lambs placed in sterile isolators at 1, 4, 8 or 9 days of age to define the role of the bacterial species that colonize the rumen just after birth. The values of the main rumen digestive parameters (pH, concentrations of volatile fatty acid, ammonia, lactic acid) in these lambs were close to those observed in conventional controls. Likewise, the digestive utilisation of the dry matter and starch was comparable in isolated and control animals but the digestibility of crude cellulose was higher in isolated lambs, which harboured only Fibrobacter succinogenes as the sole cellulolytic bacterial species. These results suggest that the rumen flora of the very young lamb play an essential role in the establishment of the rumen ecosystem and in the setting up of the digestive functions.