Monitoring mule deer diet quality and intake with fecal indices

Abstract

Few studies have evaluated fecal indices for monitoring diet quality and intake of North American deer. We conducted 11 digestion trials with black-tailed (Odocoileus hemionus columbianus Richardson) and mule deer (O. h. hemionus Rafinesque) to examine relationships between several chemical constituents of deer feces (i.e., fecal nitrogen, fecal 2,6-diaminopimelic acid (DAPA), fecal neutral detergent fiber (NDF), fecal acid detergent fiber, and fecal acid detergent lignin) and dry matter intake, digestible energy, digestible energy intake, diet crude protein content, crude protein digestibility, and digestible crude protein intake. We developed regression equations to predict diet quality and intake and also evaluated 2 alternative methods (organic matter basis and neutral detergent fiber (ndf) basis) for quantifying fecal indices. Concentrations of DAPA, fecal NDF, and fecal N were the most precise for estimating diet quality and intake. Extracts from 5 of 11 diets precipitated only small amounts of protein and influence of tannins on protein digestion probably was slight. Quantifying fecal indices per unit organic matter and neutral detergent fiber in the feces was comparable to the standard dry matter basis and under some field conditions should improve their predictive ability. We believe our best equations are suitable for management purposes where diets are similar and intake and quality are believed to be within the ranges we documented.