{
  "abstract": "Measures of protein balance, particularly changes in body mass, are important in understanding the health of wildlife populations but can be difficult or impossible to obtain from free-living animals. One potential biomarker, the δ¹⁵N value of bulk tissue, has had mixed associations with body mass. δ¹⁵N values of amino acids (AAs) have been shown to be more sensitive measures of trophic position than the bulk δ¹⁵N value and may also be more sensitive to changes in body mass. Here we evaluate AA δ¹⁵N values as a method to assess underweight status using archived serum samples from a captive population of muskoxen (Ovibos moschatus) that had decreased body mass resulting from an inadvertent dietary trace element deficiency. We predicted that AA δ¹⁵N values would be associated with deviations from the expected healthy body mass based on sex and age, and that they would be more sensitive than bulk δ¹⁵N values. We evaluated several linear mixed-effect models with δ¹⁵N values of bulk serum, AAs and other variables against deviations from expected body mass. In females, the δ¹⁵N values of glutamate/glutamine, leucine, aspartate/asparagine and serine, plus pregnancy status, were best associated with the difference from expected mass; in males, the δ¹⁵N values of glutamate/glutamine, leucine and proline were best associated with the difference from expected mass. Bulk δ¹⁵N values were not associated with the difference from expected mass. δ¹⁵N values of AAs have potential as a tool for researchers to evaluate body condition in animals.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Arctic Biology, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, Alaska 99775-7000, USA.",
    "Department of Biology and Wildlife, University of Alaska Fairbanks, 2090 Koyukuk Drive, Fairbanks, Alaska 99775-6100 USA.",
    "Animal Resources Center, University of Alaska Fairbanks, 1033 Sheenjack Drive1033 Sheenjack Drive, Fairbanks, Alaska 99775-6980, USA."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Garrett A Savory",
      "orcid": "0000-0002-5718-3421"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Molly Cook"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Greg A Breed"
    },
    {
      "affs": [
        2
      ],
      "name": "John Blake"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Diane M O'Brien"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4bpw0qt6wjfth.bib",
  "cited_by": 0,
  "doi": "10.1093/conphys/coag080",
  "fulltext_url": "https://europepmc.org/articles/PMC13688045",
  "id": "4bpw0qt6wjfth",
  "issns": [
    "2051-1434"
  ],
  "landing_url": "https://europepmc.org/article/MED/42923832",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2303|Isotope Analysis in Ecology"
    ]
  ],
  "openalex": "W7223183860",
  "pdf_url": "https://europepmc.org/articles/PMC13688045?pdf=render",
  "pmcid": "PMC13688045",
  "pmid": "42923832",
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4bpw0qt6wjfth.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:33Z",
      "native_id": "MED:42923832",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42923832"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "openalex:2303|Isotope Analysis in Ecology",
      "subfield": "ecology"
    }
  ],
  "title": "Amino acid δ ¹⁵N values are associated with underweight status in a captive population of muskoxen.",
  "title_text": "Amino acid δ ¹⁵N values are associated with underweight status in a captive population of muskoxen.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:33Z",
  "url": "https://research.draconitic.com/paper/4bpw0qt6wjfth",
  "venue": "Conservation physiology",
  "versions": []
}