EFFECT OF SOLUBLE MAILLARD REACTION-PRODUCTS ON RUMEN MICROORGANISMS

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.