Consequences to the Host of Changes in Rumen Microbial Activity

BOTH the microbial species in the rumen and the composition of the short chain fatty acids produced there as waste products of fermentation are influenced by the chemical composition, physical form and, in some circumstances, the amount of the diet. Thus, in cattle receiving barley cubes to 80% of the limit of appetite there was a high proportion of butyric acid in the mixture of short chain fatty acids associated with a large population of ciliate protozoa. With barley cubes given ad libitum there was a high proportion of propionic acid, a reduction in the number of ciliates and an increase in the bacterioides-type rods and certain curved Gram negative rods¹.