Manipulation of Rumen Fermentation and Associative Effects

Abstract

The reasons for manipulating rumen fermentation will be discussed in more detail in Chapters 6 and 7. As outlined in Chapter 2, the type of rumen fermentation determines the extent to which hydrogen, made available by anaerobic fermentation, is incorporated into compounds of use to the animal — in particular propionic acid — or is lost in the reduction of carbon dioxide to methane, with subsequent eructation. The type of fermentation can also directly influence the host animal’s metabolism by affecting its endocrine status (see Chapter 7). Thus if dairy cows absorb too much propionic acid from their rumens their blood insulin levels rise, which can seriously affect both the production and the composition of their milk. Similarly, in Jambs, too high a proportion of propionic acid, relative to the other fatty acids, results in the deposition of undesirable branched-chain soft fat (Duncan et al., 1974). Therefore methods of manipulating rumen fermentation, to optimize the ratios of different end-products of fermentation, are of practical importance, particularly for lactating animals.