Digesta retention of winter diets in white-tailed deer (Odocoileus virginianus) fawns in Maine, U.S.A.
Eight captive white-tailed deer (Odocoileus virginianus) fawns were maintained on winter diets from 15 January to 31 March 1985 (i) to determine digesta retention time for primarily coniferous diets and (ii) to test the hypothesis that lichen consumption decreased retention time. Diets contained four conifers and either 0, 5, 15, or 25 % of a fruticose lichen component. Digesta retenton time was calculated using forages that were marked with ytterbium. Feces were collected up to 168 h postdosing, and subsamples were analyzed for ytterbium by atomic absorption spectrophotometry. Across all trials, total mean retention time ranged from 48.6 to 78.8 h. Five fawns in various trials cropped off their lateral abdominal pelage and thus introduced a treatment effect into our design that restricted our statistical analysis to data from two of four trials. Those data indicated that total mean retention time decreased as proportions of dietary lichen increased for noncroppers (P = 0.007) but not for croppers (P = 0.20).