Nitrogen and Diaminopimelic Acid in Deer and Moose Feces

Abstract

We evaluated seasonal changes in fecal nitrogen (FN) and fecal 2,6 diaminopimelic acid (FDAPA) in free-ranging white-tailed deer (Odocoileus virginianus) and moose (Alces alces) in northern and southcentral Maine. The 2 fecal indices were correlated (P < 0.001) intraspecifically, but they demonstrated disparate (P < 0.005) positive relationships between cervids. A narrow range of FDAPA values for moose suggested that it might be of limited value as an index of dietary quality in moose. J. WILDL. MANAGE. 53(1):216-218 Fecal indices of dietary quality of generalized herbivores are receiving renewed research application in wildlife (Mubanga et al. 1985, Hodgman and Bowyer 1986, Beier 1987) and range management (Squires and Siebert 1983, Wofford et al. 1985) because they are economical alternatives to costly and time-intensive approaches for determining nutritional contents of diets (Hobbs et al. 1981, Leslie et al. 1984). Yet, the utility of indices such as FN is controversial (Hobbs 1987, Leslie and Starkey 1987, Robbins et al. 1987). Hobbs (1987) expressed concern about the adequacy of predictability in generalized relationships of an index and some dietary constituent. Additionally, secondary plant metabolites in diets might influence indices irrespective of dietary contents (Robbins et al. 1987). Leslie and Starkey (1987) noted that some study conditions were more conducive to the useful application of FN than others. Limitations can be abrogated by an understanding of the constraints of a particular index, a prudent application of the methodology, and tandem use of field observations of animal and/ or habitat condition (Leslie and Starkey 1987). Because of the potential application and costeffectiveness of fecal indices, Leslie and Starkey (1987) argued for continued research toward a refinement of methodology. They contended that it was premature to dispense with fecal indices because of heretofore noted constraints (Hobbs 1987, Robbins et al. 1987). Along with FN, FDAPA might be a useful index of dietary digestible energy (DDE) (Nelson and Davitt 1984). Although diaminopimelic acid (or an acid with a similar elusion time) might occur in plants (Theurer 1982), it is priarily a component of the cell walls of bacteria. Diaminopimelic acid increases in the rumen pool, as a function of increased bacterial mass. Assuming constant effects of secondary plant metabolites (Leslie and Starkey 1987), FN tends to increase as dietary nitrogen (DN) increases (Leslie and Starkey 1985). Both DDE and DN te d to increase as forage quality improves, particularly in plants of comparable digestibility. Therefore, we hypothesized that FN and FDAPA would be correlated in free-ranging whitetailed deer and moose. Further, we hypothesized that if FN and FDAPA were related, disparate relationships would exist for each cervid because of differing sizes, presumed diets, and gastrointestinal capabilities (Demment and V n Soest 1983). We are grateful to K. I. Morris and J. M. Connolly (Me. Dep. of Inland Fish. and Wildl.), M. E. Thompson, J. A. Bernatowicz, and numerous volunteers who assisted with the collection of fecal material. Earlier drafts of our paper benefited from reviews by R. T. Bowyer, B. B. D vitt, R. L. Dressler, M. F. Leslie, and J. R. Nelson. This research was supported by an award to DML from the Faculty Research Fund, University of Maine, Orono and is the Maine Agricultural Experiment Station article 1308. STUDY AREAS AND METHODS White-tailed deer feces were collected in northern and southcentral Maine, 1984-85. Col' Present address: U.S. Fish and Wildlife Service, Oklahoma Cooperative Fish and Wildlife Research Unit, Department of Zoology, Oklahoma State University, Stillwater, OK 74078.