The amount of rumen fluid influences the composition of short chain fatty acids produced in vitro
SummaryIn vitro rumen incubation systems are widely used to determine substrate degradation and the amount of fermentation products like gases, short chain fatty acids and the microbial biomass produced. Here we compare the influence of the amount of inoculum used for preparing the incubation medium on short chain fatty acid production and composition. Treatments were 10% and 30% (v/v) of filtered rumen fluid used for inoculation. In a series of experiments it was demonstrated that the two treatments did not alter the gas production or the amount of substrate truly degraded. However, SCFA production (especially acetate) was significantly reduced when only 10% of inoculum were used for incubation. We propose that acetate was taken up by rumen microorganisms as a precursor for growth, although it cannot be excluded that an altered microbial composition contributed to the observed differences.