INFLUENCE OF RUMEN FLUID AND SUBSTRATE CONCENTRATION ON FERMENTATION KINETICS MEASURED WITH A FULLY AUTOMATED TIME-RELATED GAS-PRODUCTION APPARATUS

A new fully automated time related gas production apparatus is present ed to study fermentation kinetics in rumen fluid, The newly designed a pparatus makes use of electronic pressure transducers in combination w ith electric valves to release overpressure during the incubation. In this very sensitive system, no gas accumulation and pressure build up takes place. Each valve opening represents a certain amount of gas, se t at about 0.7 mi, By recording the number of valve openings in time t he kinetics of degradation can be studied. The new equipment was used to study the influence of substrate concentration and source of numen fluid on fermentation kinetics of grass, corn cob mix (CCM) and corn s ilage (CS). With the equipment, highly accurate cumulative gas product ion curves were obtained, In some cases differences between different curves could be made more comprehensive by plotting the rate of gas pr oduction against time. The gas production curves were fitted with a mu lti-phasic model. The shape of the gas production curve was influenced by the chemical composition of the substrate, the ration of the donor animal, the adaptation of the donor animal to a ration, the time of o btaining the rumen fluid from the donor animal and the concentration o f the substrate.