Host Animal Control of Microbial Fermentation and Host Animal Digestion

Abstract

In some respects it can be said that when the ruminant animal has consumed its food the rest of the process is left essentially to the rumen microbes. However, the individual host animal can, directly or indirectly, affect and cause differences in the environment provided for fermentation. This is clearly illustrated by the fact that, when feed degradation rates were measured in a group of animals, the greatest source of variation was between individuals rather than between measurements made at different times (Mehrez & Ørskov, 1977). Moreover, the variation in ruminal outflow rate also has a large between-animal component (Ørskov et al., 1988). In this chapter the most important sources of these differences between animals are discussed.