Seasonal and Nutritional Effects on Serum Nitrogen Constituents in White-Tailed Deer

Abstract

For 21 months blood samples were drawn monthly from 4 penned adult female white-tailed deer (Odocoileus virginianus) on high diet, 6 does on low diet, and for 6 months from 3 does semistarved in winter and spring. Blood urea nitrogen (BUN) was greater (P < 0.05) in the high-diet group compared to low-diet animals, and the difference was widest during lactation. Levels of amino acid nitrogen rose in early summer, and were greater in high-diet does. Total serum proteins (TSP) decreased in low-diet deer during lactation; all parameters indicated that the does had been nutritionally stressed while nursing fawns. BUN and amino acid nitrogen became abnormally elevated and TSP sharply dropped after the winter-starved does were fasted for 1 week in April. These assays therefore appear useful in diagnosing advanced stages of malnutrition. It is essential, however, to periodically monitor blood constituents to validly appraise the overwinter nutritional history of deer. J. WILDL. MANAGE. 43(2):454-460 Blood characteristics of white-tailed deer have been investigated to assess the physical condition of free-roaming herds. Levels of nitrogen products in blood are believed to reflect protein and energy metabolism in domestic ruminants (Preston et al. 1965) and in deer (Seal et al. 1972, Kirkpatrick et al. 1975). Studies of blood urea nitrogen and serum proteins suggest that these constituents provide sensitive measures of nutritional status in wild cervids (LeResche et al. 1974). Like other ruminants, deer increase the percentage of recycled urea as protein content of their diet decreases (Robbins et al. 1974). Generally, however, the studies on deer were of short duration, done intermittently throughout the year, or lacked suitable controls. LeResche et al. (1974) summarized the published data from periodic investigations on Cervidae and concluded that most blood assays surveyed showed seasonal variations. The magnitude of such changes was not clear because serial samples on the same animals were lacking. Because many blood chemistry factors reflect environmental influences as well as an animal's physiological state, there is a need for longterm studies on deer of known nutritional history. The objective of this research was to quantify the seasonal variation in nitrogen products in the blood of penned adult does maintained continuously on a high or low dietary plane. Determinations of serum proteins, blood urea nitrogen, plasma amino acid nitrogen, and packed cell volume from these animals are presented here. Assays of other parameters will be reported elsewhere. We thank D. Rinkeviczie and D. Pesola for performing laboratory analyses, and D. DeLisle and C. Bienz for husbandry and handling of animals. The assistance of D. E. Ullrey in formulating the lowdiet ration is gratefully acknowledged.