Synthesis of ruminal microbial protein and volatile fatty acid production in vitro.

Growth of a mixed ruminal population taken from a sheep on a protein-free (all urea) purified diet was estimated by an in vitro fermentation technique including precipitation of microbial protein by trichloracetic acid. Volatile fatty acid production in vitro was determined, and the associated a denosine triphosphate was estimated as moles volatile fatty acids X 2.4. On this basis, the quantity of microbial protein synthesized per mole of adenosine triphosphate increased at higher microbial growth rates.