Reproductive effects on fecal nitrogen as an index of diet quality: an experimental assessment

Journal of Mammalogy
South Dakota Agricultural Experiment Station; Department of Natural Resource Management at South Dakota State University; Idaho State Univ; Univ Wyoming, Dept Zool & Physiol; S Dakota State Univ, Dept Nat Resource Management; Oklahoma State Univ
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Concentration of fecal nitrogen has been used widely as an indicator of dietary quality for free-ranging ruminants. Differences in digestive function between species of dimorphic ungulates render interspecific comparisons of fecal nitrogen unreliable; however, whether intraspecific sexual differences in digestive function also bias this nutritional index is unknown. Our objective was to compare sex-specific variation in concentration of fecal nitrogen using male, nonlactating female, and lactating female white-tailed deer (Odocoileus virginianus) on high- and low-quality diets. During weekly trials over spring and summer (2008-2009), we monitored intake rates, collected feces twice daily, and used micro-Kjeldahl procedures to determine percent fecal nitrogen. We 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 than for males or nonlactating females throughout lactation. Nitrogen concentration following an NDF rinse also was lower for lactating females during peak lactation. We hypothesize that the remodeling of the digestive tract and increased rumination by lactating females may enhance their ability to extract nitrogen from their forage. These adjustments may expand the foraging options of lactating females by increasing their ability to process low-quality foods, but also affects the interpretation of fecal nitrogen during the season of lactation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Reproductive effects on fecal nitrogen as an index of diet quality: an experimental assessment
Series title Journal of Mammalogy
DOI 10.1644/12-MAMM-A-306.1
Volume 95
Issue 2
Year Published 2014
Language English
Publisher American Society of Mammalogists
Publisher location Lawrence, KS
Contributing office(s) Coop Res Unit Atlanta
Description 10 p.
First page 301
Last page 310
Online Only (Y/N) N
Additional Online Files (Y/N) N