Increasing supplementation of feedlot finishing diet with a mixture of REE from 0,
400 to 800 mg/kg of diet linearly increased VFA concentration in the batch culture trial;
whereas, in the CC trial, supplementation of REE had minimal effect on VFA profiles
except for increased proportion of butyrate with the high dosage of REE. The discrepancy
between the two culture trials could be attributed to difference in the concentration of REE
in the incubation solution. Improvement of the digestibilities of DM and OM due to REE
supplementation was attributed to the increase in digestibility of fibre and degradability of
protein. The results suggest that REE supplementation improved fibrolytic bacterial activity
as well as proteolytic activity. Furthermore, REE modulate the microbial activity in a dosedependent manner. The increase of digestibility by increasing REE from 400 to 800 mg/kg
of diet was marginal. In addition, in vitro rumen fermentation pattern could be substantially
different from same substrate if media pH differs