Comparing protein and energy status of winter-fed white-tailed deer

Although nutritional status in response to controlled feeding trials has been extensively studied in captive white-tailed deer (Odocoileus virginianus), there remains a considerable gap in understanding the influence of variable supplemental feeding protocols on free-ranging deer. Consequently, across the northern portion of the white-tailed deer range, numerous property managers are investing substantial resources into winter supplemental-feeding programs without adequate tools to assess the nutritional status of their populations. We studied the influence of a supplemental winter feeding gradient on the protein and energy status of free-ranging white-tailed deer in the Adirondack Mountains of New York. We collected blood and fecal samples from 31 captured fawns across 3 sites that varied considerably in the frequency, quantity, and method of supplemental feed distribution. To facilitate population-wide comparisons, we collected fresh fecal samples off the snow at each of the 3 sites with supplemental feeding and 1 reference site where no feeding occurred. Results indicated that the method of feed distribution, in addition to quantity and frequency, can affect the nutritional status of deer. The least intensively fed population showed considerable overlap in diet quality with the unfed population in a principal components ordination, despite the substantial time and financial resources invested in the feeding program. Data from fecal samples generally denoted a gradient in diet quality and digestibility that corresponded with the availability of supplements. Our results further demonstrated that fecal nitrogen and fecal fiber, indices of dietary protein and digestibility, can be estimated using regressions of fecal pellet mass, enabling a rapid qualitative assessment of diet quality.