Rate and Extent of Digestion and Potentially Digestible Cell Wall of Waste Papers1

In vitro digestion characteristics were determined for eight waste papers. Office bond, solka floe and paper bags had small indigestible cell wall residues (8.04 to 16.57%), large amounts of potentially digestible cell wall (81.86 to 88.16%) and large digestion constants (.0450 to .0540). Unwaxed corrugated papers had moderate indigestible residues (26.10 and 27.59%), moderate potentially digestible cell wall (68.93 and 69.56%) and moderate to high rate constants (.0382 and .0552). Waxed corrugated papers and newsprint contained large indigestible cell wall residues (45.78 to 70.83%), small amounts of potentially digestible cell wall (27.19 to 48.19%) and low to moderate rate constants (.0185 to .0492). Office bond, solka floe and paper bags contained enough potentially digestible fiber to be useful in ruminant diets. Waxed corrugated paper and newspaper were very low in potentially digestible fiber and appeared to have very limited value in ruminant diets. Unwaxed corrugated paper was intermediary as a ruminant fiber source. Presence of wax increased the indigestible residue and decreased the rate constant of corrugated paper; lignin appeared to limit extent and rate of digestion of most papers.