Pronghorn study links nutrition and stress across reproductive stages

A new pronghorn study in Animals examines how nutrition and stress biology change across major reproductive stages in wild, free-ranging adult females, with an eye toward understanding how physiology tracks the demands of late gestation, early lactation, and breeding season. The paper fits into a broader Idaho research effort led by Cole A. Bleke and colleagues that uses noninvasive fecal sampling to study nutrition, diet, pregnancy, and glucocorticoid activity in a species that is notably sensitive to capture. (digitalcommons.usu.edu)

That background matters. In his Utah State University dissertation, Bleke described the larger project as an effort to understand how adult female pronghorn physiology influences fawn summer survival without relying on invasive handling. The team measured fecal nitrogen, 2,6-diaminopimelic acid, diet composition, and cortisol-related metabolites during metabolically demanding life-history periods. The same research program also produced a 2023 PLOS ONE paper showing that female pronghorn diets in southern and southeastern Idaho were dominated by forbs, with protein intake from forbs peaking during early lactation. (digitalcommons.usu.edu)

The newly highlighted Animals article focuses on integrating nutrition and glucocorticoid activity across those life-history stages. While the full text was not readily accessible in search results, the related 2024 Animals paper from the same dataset reported that samples were collected across five subpopulations over two years and that intrinsic measures included fecal glucocorticoid metabolites, fecal nitrogen, DAPA, and diet composition, alongside NDVI as an environmental measure. That analysis found stage-specific relationships: late-gestation variation in digestibility and dietary protein metrics was linked with recruitment, early-lactation fecal nitrogen showed the strongest positive association with fawn recruitment, and breeding-season greenness was tied to the following year’s recruitment. (digitalcommons.unl.edu)

The diet findings help explain the physiology. In the PLOS ONE study, plant DNA barcoding identified 137 plant species in pronghorn diets, with forbs making up the largest share overall. Protein intake from cultivated legumes such as alfalfa was lower than expected, suggesting that forage selection was influenced by more than crude nutrient availability alone. The dissertation similarly concluded that females appeared to shift between diets higher in nitrogen or digestible energy depending on life-history demands. (journals.plos.org)

Expert reaction specific to this paper was limited in publicly indexed coverage, but the broader literature supports the study’s framing. Reviews in Journal of Mammalogy and recent PubMed-indexed wildlife endocrinology papers emphasize that glucocorticoid measures in free-ranging mammals vary with life-history stage, reproductive status, food availability, and environmental challenge, and that fecal metabolites are useful but context-dependent indicators of physiological load rather than simple readouts of “bad stress.” (academic.oup.com)

Why it matters: For veterinary professionals working in wildlife, conservation medicine, zoological health, or mixed public-private herd health systems, the practical takeaway is that nutrition and stress biology need to be interpreted together. A high glucocorticoid signal in a lactating female may reflect adaptive energy mobilization, poor forage conditions, reproductive burden, or some combination of all three. Noninvasive fecal sampling offers a way to monitor these dynamics with less handling bias in a capture-sensitive species, and the Idaho findings suggest that early-lactation diet quality may be a particularly informative window for predicting downstream recruitment. (digitalcommons.usu.edu)

The study also has management relevance beyond pronghorn. The authors’ related 2024 paper explicitly argues that low-recruitment subpopulations may benefit from efforts to increase nitrogen-rich forage available to adult females during early lactation, while still interpreting results at the subpopulation level rather than assuming one statewide pattern. For veterinarians advising agencies, NGOs, or land managers, that points toward more targeted habitat and monitoring strategies, rather than relying on body condition or mortality data alone. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next step is whether this line of work yields management thresholds that agencies can use operationally, such as fecal nitrogen or glucocorticoid benchmarks linked to poor recruitment years, and whether similar noninvasive models hold up in other free-ranging ungulates facing drought, habitat change, or increasing human disturbance. (pubmed.ncbi.nlm.nih.gov)