Indigestible Particulate Passage in White-Tailed Deer

Abstract

Relationships among intake, digestion, and passage rates for white–tailed deer (Odocoileus virginianus) eating guajillo (Acacia berlandieri) were examined in a completely randomized balanced design metabolism experiment. Dry matter intake was positively correlated (P = 0.0005) with rate of indigestible particle disappearance from the rumen. The more highly digested diets had longer ruminal and total tract mean retention times (MRT). There were seasonal differences in ruminal and total tract MRT. Differences in total tract MRT were a function of ruminal turnover rates, not of time spent in the lower tract. No chemical or physical criteria were related directly to ruminal or total tract MRT. Dietary NDF concentrations varied seasonally, but permanganate lignin concentration was similar across seasons. Passage rates were not a function of permanganate lignin concentration; rather, low cell wall content of the forage allowed for rapid excretion of indigestible particles.