The Influence of Certain Physical Properties of Purified Celluloses and Forage Celluloses on Their Digestibility by Rumen Microorganisms in vitro

Publisher Website
Google Scholar
Abstract
The susceptibility of purified celluloses to attack by rumen microorganisms in vitro is influenced by the source or the method of preparation. Cotton linters, a native fiber, which is known to be highly crystalline was digested at a slower rate than samples of isolated wood celluloses. This difference was not due to particle size or to the average mass of the glucose chains making up the fibrils expressed as degree of polymerization. Examination of the samples with an X-ray diffractometer revealed differences in the height-width ratio of the main peaks of the X-ray patterns. This ratio was found to be correlated with the digestibility of the sample. Indeed, it is suggested that this parameter may be a crude estimation of degree of packing perfection. In any case it would appear that this parameter was indicative of a relationship between the susceptibility of cellulose to microbial digestion and the physical characteristics responsible for the X-ray diffraction patterns obtained. Furthermore, this observation would suggest that the activity of cellulases from rumen organisms are affected by cellulose structure in much the same manner as the cellulases isolated from molds and soil organisms which attack cellulose in cloth or cellulose present in soil residue. Forages of varying cellulose digestibility (in vitro) and isolated forage holocelluloses were examined by the same X-ray procedure. No differences were detected in the X-ray patterns and the results suggested that these celluloses were more amorphous than the purified isolated celluloses. It appears that native celluloses as present in forage plants should be readily digested if contact is made between them and the rumen organisms or microbial cellulases. Copyright © . .