After incubation of Maillard reaction polymers (MRPs) with rumen fluid
from wethers neither volatile fatty acids nor lactate were produced.
Soluble polymeric products of the Maillard reaction were nonmetaboliza
ble by a mixed culture of rumen microorganisms. MRPs added at 0.5 and
2 g/L inhibited the growth of seven ruminal Gram-negative bacteria by
20 and 30 %, respectively. In four strains of Gram-positive bacteria,
MRPs lowered the cell concentration by 11 % (0.5 g/L) and 25 % (2 g/L)
. The rumen fungus Orpinomyces joyonii also did not metabolize soluble
MRPs.