Predicting Energy and Nitrogen Retention in Young White-Tailed Deer

Abstract

To estimate carrying capacity of habitat for white-tailed deer (Odocoileus virginianus) it is necessary to know the energy and nutrient needs of various age-classes of deer and the value of various diet components in meeting these needs. To define energy requirements of young deer, age, weight, and intakes of digestible nitrogen and digestible or metabolizable energy from 207 balance trials were used to predict body retention of fat, protein, and energy. Caloric requirements for body energy maintenance were determined for fall and fawns and summer yearlings. Using maximum body protein or energy retention as criteria for maximum growth, caloric requirements for maintenance-plus-growth were determined in fall fawns and, based on protein retention only, in summer yearlings. This information will be useful in estimating carrying capacity. J. WILDL. MANAGE. 43(4):880-888 Intensified management of white-tailed deer likely will involve estimation of carrying capacities for which a knowledge of nutritional requirements is essential. Undernutrition during severe northern winter and early spring conditions sometimes results in serious losses, particularly among younger age-classes. Several workers (Thompson et al. 1973, Short 1975, Holter et al. 1977a) have studied the effects of season on food intake and weight change in deer. A number of estimates have been made of maintenance energy requirements. Thompson et al. (1973) found that fawns require 166, 109, and 163 kcal metabolizable energy per kilogram metabolic body weight (Wo'75) in October, January, and May, respectively; the corresponding value for yearlings in August was 192. For fawns (Dec through Apr), Holter et al. (1977a) reported maintenance metabolizable (MEMT) and net (NEMT) energy requirements of 153 and 97 kcal/kgWo'75 and, for yearlings (May through Oct), 162 and 125 kcal/kgWo075, respectively. Ullrey et al. (1970) estimated MEMT in pregnant does to be 131 kcal/ kgWo.75. Finally, Magruder et al. (1957) published general estimates of energy needs for maintenance and growth/fatt ning in yearling and adult deer in terms of daily gross energy intake of a top quality diet; they measured response in terms of body weight change. It is apparent that energy needs of deer vary with age, season, and perhaps other factors. No definitive estimates of energy required for growth of deer are available. It appears that negative energy balance may be more likely to occur than negative nitrogen balance, especially during the winter-early spring period in norther deer. It has been shown (Holter et al. 1977a) that body weight gain as an indicator of growth is not closely correlated with deposition of body nitrogen or energy. The objectives of our study were to combine energy and nitrogen balances from a number of experiments in order to predict body retention of protein, fat, and energy; and to ascertain the rates of energy intake at which deposition of energy and protein are zero (maintenance) and maximum (maintenance + growth). We gratefully acknowledge the labo1 Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as Scientific Contribution 888. 880 J. Wildl. Manage. 43(4):1979 This content downloaded from 207.46.13.113 on Thu, 06 Oct 2016 04:06:31 UTC All use subject to http://about.jstor.org/terms ENERGY AND NITROGEN RETENTION IN DEER* Holter et al. 881 ratory assistance of T. Kenna and the statistical help of W. E. Vinson, M. L. McGilliard, and C. A. Brown. Computer facilities were provided through the generosity of P. T. Chandler.