Role of Protozoa in the Rumen

Abstract

Measurement of various ruminal parameters in faunated, defaunated, and ciliate-free animals indicate that the ruminal environment can be markedly altered by the presence of protozoa (Table 10.1; Williams and Coleman, 1988). These changes in the ruminal ecosystem will have an effect on the bacterial activities, and hence the supply of metabolites to the host will be affected. The presence of protozoa in the rumen has been shown to influence the volume of the rumen and the retention time of the digesta, the concentration and proportion of the volatile fatty acids, the levels of other acidic metabolites and ammonia, the environmental pH, and the numbers and type of rumen bacteria present. Changes in any of these parameters will influence ruminal function with resultant beneficial or detrimental consequences for the host.