Do bulk nitrogen isotope ratios capture declines in captive muskox body condition?

Molly Cook et al.
Wed, 22 Apr 2026 18:29:54 PDT

We were interested in studying muskox bulk nitrogen isotope ratios to see if these values capture declines in body condition. We were particularly interested in using archived serum from muskox at the University of Alaska Fairbanks Large Animal Research Station from 2009-2010 when there was a decline in the body condition of some individuals due to deficiency in trace minerals. Nitrogen isotope ratios can be analyzed to assess protein balance in animals. Since the lighter isotope of nitrogen (14N) is preferentially excreted in urine, the heavier isotope of nitrogen (15N) is enriched in tissues. As a result, we expect to see a decrease in N15 ratios when an animal is in a state of emaciation.