Comparison of comprehensive health score in North American housed giraffe and free-ranging giraffe from South Africa

As in humans, stress is evident in many animal species and has been correlated to disease prevalence; yet a value for reliable quantification of chronic stress is unestablished. During stressful events, allostasis, an adaptive process, is initiated by physiologic systems to maintain or reestablish homeostasis to protect an organism’s viability. Over time, the acclimation to frequent stress causes systematic dysregulation, leading to the phenomena of increased allostatic load. In recent studies, allostatic load has been assessed in animal species via serum through selection of representative, multi-system biomarker indices. Perception and number of stress events an individual experiences may impact dysregulation severity, yielding allostatic load as a valuable tool in predicting future outcomes. However, the allostatic load methodology poses application limitations to individuals without historical data and those lacking a conscious recognition of stress. Comprehensive health score may be more encompassing of populations, as it targets biomarkers dysregulated by life events associated with pathology, despite an unknown level of cognition or history. Serum samples were obtained from zoo-housed (n=18) and free-ranging (n=11) giraffe to predict subclinical risk of morbidity and mortality caused by chronic stress. Serum concentrations of selected biomarkers were investigated using colorimetric ELISAs (cortisol, DHEA-S), the CHOD-PAP method (cholesterol), colorimetric enzymatic method (NEFA), and nitroblue tetrazolium assay (fructosamine). Selection of these biomarkers were based on the ability to estimate dysregulation of physiologic processes impacted by stress accumulation, such as the neuroendocrine, metabolic, and inflammatory systems. Free-ranging giraffe were younger (m = 7.9 years) on average and had lower cholesterol (p = 0.016) and fructosamine (p = 0.039) levels when compared to captive giraffe (m = 12.8 years). Additionally, free-ranging giraffe had higher cortisol (p = 0.007) levels and NEFA (p = 0.004) status, while DHEA-S (p = 0.548) was found at relatively similar concentrations between the populations. Although suitable composites rely heavily on specific species and environmental factors, comprehensive health score provides a foundation for a more applicable tool in conservation research through comparison of biomarkers across populations.

Publish DateApril 22, 2021
Last UpdatedApril 22, 2021