24-HOUR URINARY CREATININE AND UREA NITROGEN-EXCRETION IN MALE WHITE-TAILED DEER

During 5-d trials in spring and summer we investigated the constancy o f creatinine and urea nitrogen excretion and the urea nitrogen:creatin ine ratio in 24-h urine samples from 12 male white-tailed deer (Odocoi leus virginianus) and the relationship of these metabolites with body mass and dietary nitrogen intake. During both trials, 24-h urinary cre atinine excretion remained stable (CV of 13.5 and 18.5% for the spring and summer trials, respectively), and there was no difference between deer fed a high-protein diet and those fed a low-protein diet. Howeve r, urinary urea nitrogen excretion and urea nitrogen:creatinine ratios were significantly lower in the latter group. Mean daily creatinine c oefficients (0.22-0.27 mmol excreted/kg body mass) were comparable to those in other mammalian species. During both trials, urinary creatini ne excretion was significantly related to body mass but not to dietary nitrogen intake. Urea nitrogen excretion and urea nitrogen:creatinine ratios were significantly related to mass-specific nitrogen intake, b ut not to body mass or 24-h urinary creatinine excretion. Using 24-h u rinary creatinine excretion, mean muscle mass of our deer was estimate d to be 58 and 57% of whole body mass in the spring and summer trials, respectively.