Cellulose digestion and metabolism by captive rock ptarmigan.

-l, Carbon-14 labeled cellulose was fed to rock ptarmigan to provide evidence of cellulose digestion and metabolism. Digestibility of cellulose and energy metabolized by ptarmigan fed a diet of 6 and 30';0 cellulose were determined by a feeding trial. 2. Recovery of t'~CO2 in expired gases from ptarmigan fed t*C labeled cellulose demonstrates the digestion and metabolism of cellulose by gut microbes and the ptarmigan. 3, Rapid recovery of 14CO 2 in expired gases suggested preeccat digestion of cellulose, 4. Cellulose digestibility averaged 34~; and was not signiticantly different between groups of birds, however, total cellulose digestion was significantly different in birds fed 6 and 309~, cellulose diets, 0-4 and 3.7 g/day, respectively. 5. Indirect evidence is presented which suggests cellulose digestion in the cecum is relatively eol~aplete. 6, Caged existence energy averaged 63 kcal/day and was not significantly different between birds fed low and high cellulose diets.