The present study evaluated and characterized various types of biomass fermented in the rumen culture. A series of batch experiments were conducted to assess any potential organic acid build-up in the rumen culture fermenting different substrates of biomass. Results showed that pH depression occurred within 2 h of incubation in the rumen culture fermenting rice bran and/or concentrate in which the pH dropped from the neutral level (pH 6.9 ± 0.15) to the acidic level (pH 5.6 ± 0.15). However, at the same period of incubation, the fermentation of grass and tofu pulp in the rumen culture did not have a dramatic drop of pH in which the pH was somewhat stable between 7.0 and 6.85. Organic acids, such as acetic acid and lactic acid, were accumulated in the digesters of rumen culture fermenting rice bran and/or concentrate, suggesting that the culture was acidified which led to ruminal acidosis.
Key words: Rumen, acidosis, fermentation, biomass
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