title: Analysis of hair cortisol levels in captive chimpanzees: Effect of various methods on cortisol stability and variability.
abstract: Hair cortisol has been reported to be a useful measure of long-term hypothalamic-pituitary-adrenal (HPA) axis activation in several species. It serves as a practical tool for long-term stress assessment, but it is important to understand the methodological factors that can affects hair cortisol assays to avoid methodological artifacts. To that end, we tested several procedures for measuring cortisol levels in hair collected from captive chimpanzees. The results showed that reproducibility was high, and we found no differences in cortisol levels among the various storage, drying, and sampling methods. However, the fineness of homogenized hair, sample weight, and extraction time affected absolute hair cortisol concentration. Although hair cortisol levels were stable over time, factors that may influence measurement results should be kept constant throughout a study.•We modified and validated a methodology involving enzyme immunoassays to reliably measure the hair cortisol levels of captive chimpanzees.•The results revealed that the fineness of homogenized hair, sample weight, and extraction time caused variations in absolute hair cortisol concentrations in chimpanzees. In contrast, storage, drying, and sampling from similar body parts did not affect the results.
authors: Wildlife Research Center, Kyoto University, Japan.
authors: Yumi
authors: Y
authors: Yamanashi
authors: Wildlife Research Center, Kyoto University, Japan.
authors: Migaku
authors: M
authors: Teramoto
authors: Wildlife Research Center, Kyoto University, Japan.
authors: Naruki
authors: N
authors: Morimura
authors: Wildlife Research Center, Kyoto University, Japan.
authors: Satoshi
authors: S
authors: Hirata
authors: Primate Research Institute, Kyoto University, Japan.
authors: Juri
authors: J
authors: Suzuki
authors: Primate Research Institute, Kyoto University, Japan.
authors: Misato
authors: M
authors: Hayashi
authors: Primate Research Institute, Kyoto University, Japan.
authors: Kodzue
authors: K
authors: Kinoshita
authors: Wildlife Research Center, Kyoto University, Japan; National Institute for Environmental Studies, Japan.
authors: Miho
authors: M
authors: Murayama
authors: Wildlife Research Center, Kyoto University, Japan.
authors: Gen'ichi
authors: G
authors: Idani
keywords: Animal welfare; Chimpanzee; Hair cortisol; Long-term stress; Practical methodology