Is It Getting in the Hair? Cortisol Concentrations in Native, Regrown, and Segmented Hairs of Cattle and Pigs After Repeated ACTH Administrations

The study examined the effect of repeated ACTH administrations on hair cortisol concentrations (HCCs) in 34 cattle and 38 pigs to validate HCC as a stress indicator. In cattle, HCCs in natural, regrown, and segmented hair significantly increased after ACTH treatment, indicating heightened HPA axis activity and making HCC a promising stress indicator. In contrast, pigs showed no significant differences in HCCs between treated and control groups, likely due to a blunted cortisol response, seasonal hair growth, and contamination, suggesting HCC is less reliable for stress assessment in pigs under commercial conditions. The study emphasized the importance of considering external contamination and species-specific factors when using hair cortisol as a biomarker for stress.