A New Method for the Study in Vitro of Rumen Digestion

Abstract

To evaluate inhibition of cellulose digestion in vitro by the accumulation of non-gaseous fermentation products, these workers compare cellulose digestion carried on in a glass container and that carried on in a cellulose dialysis bag immersed in a large volume of aqueous growth medium. In both sets of conditions aliquots of strained rumen samples from fistulated cow rumen were allowed to act on ground Whatman No. 12 filter paper at pH 6.8 (adjusted by addition of 0.5[image] Na2CO3 at 2-hr. intervals) under anaerobic conditions maintained by a flow of N2 gas containing 5% CO2, stirred at intervals, and maintained thermostatically at 39[degree]C. At the end of 24 hrs. aliquots were taken for the detn. of residual cellulose, and in one expt., the production of volatile organic acids. In all 4 sets of expts. reported, the amt. of cellulose digested in the dialysis bag exceeded that in the glass bottle by 19-78% of the latter value. In general the difference was proportional to the absolute amt. of cellulose digested. These observations indicate a definite inhibition of cellulose digestion by rumen flora in vitro by accumulated metabolic products.