Mineral Metabolism by White-tailed Deer Fed Diets of Guajillo

Author(s): Tyler A. Campbell and David G. Hewitt
Published: December 2005

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Seasonal scarcity of forbs in southern Texas often requires white-tailed deer (Odocoileus virginianus) to subsist on browse. Deer might seek minerals during periods of high browse consumption as buffers or as precursors to conjugate-based detoxification of plant secondary compounds (PSCs) contained in many browse species. To determine importance of plant secondary compounds on mineral consumption, we fed diets of 0, 25, 50, and 75% guajillo (Acacia berlandieri), a browse species high in PSCs, to 4 male white-tailed deer in a Latin square design experiment, and we compared mineral metabolism and determined how well guajillo met mineral requirements for maintenance and productive processes as described in the literature. Concentrations of calcium, phosphorus, and sodium in the diet decreased with increases in guajillo, whereas magnesium concentration did not change. Losses of calcium, phosphorus, and magnesium occurred largely via fecal excretion, whereas sodium losses occurred via urinary excretion. Calcium, magnesium, and sodium intake rates from diets up to 100% guajillo exceeded requirements. Adult males met summer and fall phosphorus requirements with diets of 100% guajillo and their spring and annual requirements were met with diets of <75 and 97% guajillo, respectively. Phosphorus supplementation during periods of low rainfall and high guajillo consumption might reduce the phosphorus deficit in reproducing females.