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Open Access Publications from the University of California

Effects of forage nutritional quality (energy and protein) on deer acceptance of foods containing secondary metabolites

  • Author(s): Nolte, Dale L.
  • Kimball, Bruce A.
  • Perry, Kelly R.
  • Villalba, Juan J.
  • Provenza, Frederick D.
  • et al.

Deer foraging on tree seedlings is recognized as the most widespread detriment to reforestation efforts. Non-lethal approaches to reduce deer damage to seedlings are highly desirable. Avoidance of natural secondary metabolites contained in conifers may provide feasible means to develop non-lethal measures. Other studies have demonstrated that sheep and goats fed diets with high protein-to-energy ratios, or allowed to select between concentrates high in either energy or protein, ate much more of a high-terpene diet and of a high-tannin diet than when they were fed diets high in energy-to-protein ratios. Thus, manipulating foraging options for deer may impact their ability to ingest terpenes contained in conifers. We conducted a series of studies to determine whether deer acceptance of terpene-containing foods can be affected by altering the ratio of energy and protein in their maintenance diet. We determined relative consumption of a high-energy and low-protein diet, and a low-energy and high-protein diet, when deer are given the opportunity to self-regulate their intake. We also determined if deer modified their relative intake of these diets when offered an alternative terpene-treated diet. Penned deer were offered variable diets (e.g., high energy-low protein, low-energy-high protein, or both foods), then their acceptance of terpene- and tannin-containing foods was determined. Deer consumed more and demonstrated a strong preference for the high-energy diet relative to the high-protein diet. However, the varied diets did not appear to affect their intake of terpene or tannin-containing foods. This paper discusses the potential of manipulating maintenance rations as a non-lethal tool, presents initial results and possible explanations for differences between our study with deer and prior work with domestic ruminants.

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