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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Natural Resource Management

First Advisor

Jonathan A. Jenks


Concentration of fecal nitrogen has been used widely as an indicator of forage quality for free-ranging ruminants. Differences in digestive function between species of dimorphic ungulates render interspecific comparisons of fecal nitrogen unreliable; however, it is unknown whether sexual differences in digestive function also may bias this nutritional index. My objective was to compare sex-specific variation in the concentration of fecal nitrogen using male, non-lactating female, and lactating female white-tailed deer (Odocoileus virginianus) on control and restricted diets. During weekly trials, I monitored intake rates, collected feces twice daily, and used Micro Kjeldahl procedures to determine percent fecal nitrogen. I also determined nitrogen content of feces following a neutral detergent fiber (NDF) rinse during pre-, peak-, and postlactation. Fecal nitrogen reflected general differences in dietary quality between diets; however, fecal nitrogen of lactating females in both dietary groups was lower (P < 0.05) than for males or non-lactating females throughout the lactation period. In addition, nitrogen concentration following a neutral detergent fiber rinse was lower for lactating females during peak lactation. I hypothesize that the remodeling of the digestive tract by lactating females enhances their ability to extract nitrogen from their forage; therefore, fecal nitrogen is influenced by reproductive status of females. Agricultural producers lose millions of dollars annually to depredation caused by ungulates; although multiple repellents exist for deer, most are ineffective. Tannins are a plant defensive compound that have an astringent taste, reduce digestibility, reduce protein availability, and are toxic to rumen microbes, resulting in the reduction in feeding by large herbivores. I hypothesized that chemical application of tannins to soybeans and other forages would provide a non-lethal method to reduce crop depredation in areas susceptible to deer damage. I designed an experiment to test the effectiveness of tannins at deterring feeding by captive white-tailed deer (Odocoileus virginianus) on soybeans and other forages in 2010-2011. First, using a cafeteria trial, I monitored weekly intake rates of captive deer (n=10) offered a highly-preferred feed treated with varying concentrations of quebracho tannins (control, 3%, 5%, 10%, and 20%). Second, I manipulated food plots (n=3) by treating 3 separate blocks with different concentrations (0% [control], 10%, and 20%) of tannins. I monitored feeding preference relative to tannin treatments within food plots three times per week, during mid- (May – July) and late-summer (August – September) using scan sampling. During cafeteria trials, intake rate of control feed was at least three times greater (all P < 0.05) than all other tannin treated feeds. Similarly, in manipulated food plots, application of 10% and 20% tannins resulted in a 72% and 89% reduction in probability of feeding during the summer; this pattern of preference was intensified when trials occurred on consecutive days (P<0.001). Strategic application of tannins to agricultural crops may provide a natural deterrent to deer depredation. In a free-ranging assessment, I designed an experiment to test the effectiveness of tannins to deter feeding by white-tailed deer on corn and soybeans in areas of high white-tailed deer density in 2010-2011. I monitored depredation in strategically placed plots (n = 25) in agricultural fields in eastern South Dakota. Each plot consisted of three treatments; control, 10% tannins, and 20% tannins. I counted number of plants browsed on a weekly basis to assess total amount of depredation. In 2011, I added an adjuvant to the tannin concentration to increase retention on the plants. Corn and soybean plots without the adjuvant deterred feeding 7% to 36%, whereas corn and soybeans with the adjuvant deterred feeding by 0% to 20%. Strategic application of tannins to agricultural crops may provide a natural deterrent to deer depredation.

Library of Congress Subject Headings

White-tailed deer -- Nutrition
White-tailed deer -- Nutrition -- Sex differences
Nitrogen in animal nutrition


Includes bibliographical references.



Number of Pages



South Dakota State University


Copyright © 2012 Kyle Bradley Monteith. All rights reserved.