Winter diets of ruffed grouse (Bonasa umbellus) and other galliformes
are high in tannins. We fed quebracho, a condensed tannin, to ruffed g
rouse and found no effect on dry matter intake or body mass at levels
up to 6% of the diet. However, a high-fiber diet with 8% quebracho res
ulted in reduced dry matter intake and body mass loss. Grouse could no
t tolerate a diet with 8% tannic acid, a hydrolyzable tannin, which ca
used a large reduction in dry matter intake and body mass. Northern bo
bwhite (Colinus virginianus) and ruffed grouse responded to dietary qu
ebracho tannin by increasing the proportion of digesta that was excret
ed from the ceca. In the northern bobwhite, 59%-76% of the tannin reco
vered from the feces was in cecal feces. There was no difference in av
erage passage rates of liquid and fiber digesta, although variation wa
s high in tannin-fed birds. The role of the ceca in handling tannin re
quires further investigation.