Fecal nitrogen and dietary quality relationship in fallow deer

Fecal nitrogen of free ranging and captive herbivores is correlated with dietary nitrogen, as well as other dietary chemical characteristics. Besides, only few experimental studies examined in depth the precision of these relationships. This study investigates the correlation between fecal and dietary nitrogen in fallow deer (Dama dama), using data from 38 feeding trials collected from captive subjects. Significant linear regressions were found for all the dietary and fecal chemical components, but only nitrogen showed a noteworthy result (R2=0.76), very similar to the results obtained by several authors in other deer species (Robbins, 1993). Use of fecal nitrogen however, has been criticised because plant secondary compounds, such as tannin, may artificially inflate levels of fecal nitrogen; moreover, the binding effect of tannin is strongly reduced in mixed diets. After all, fecal nitrogen confirms its usefulness in studies about feeding strategies of free living ruminants.