The rates of production of volatile fatty acids in the rumen. II Measurements of production of volatile fatty acids in the rumen

Abstract

(1) The production of acetic, propionic, and butyric acids was measured in an artificial rumen of the dialysing type: (a) by direct analysis, and (b) by the isotope dilution technique with 14C-labelled fatty acids. Estimates of production by the latter method agreed closely with the direct measurements when due allowance was made for small losses of the radioactive labels from their respective acids. (2) Rates of production of the three acids in the rumen of the sheep were measured simultaneously by the isotope dilution technique. The small losses of 14C from the acids were measured in the same material fermented in an artificial rumen which was shown to produce a mixture of the acids in the same proportions as the fermentation in 'the rumen itself.