Abstract
The ruminal activity, daily live-weight gain and feed conversion efficiency of zebu calves inoculated with whole rumen contents from a mature cow were compared with those of calves maintained under the same conditions except that they were ciliate-free and isolated from other ruminants. A thriving mixed population of ciliate protozoa became established in the rumen of calves two weeks after inoculation. Entodinium was the first genus to appear and was followed by Isotricha, Polyplastron, Ophryoscolex, Diplodinium and Dasytricha. The ruminal volatile fatty acid and ammonia concentrations in the inoculated calves showed a pronounced rise above the values found in the uninoculated controls. The inoculated calves grew faster and had a higher feed conversion efficiency than the uninoculated controls.