Measures to quantify long-term or chronic stress in livestock are limited. The amount of cortisol (a stress hormone) deposited in the hair has been used as a noninvasive measure of long-term stress in some livestock species; however, few studies have investigated its use in young dairy calves. The objective of this study was to determine the efficacy of hair cortisol as a less invasive measure of stress in calves. Calves were either injected with saline (control) or Cosyntropin, a hormone that activates the stress response system, at different frequencies during the first two months of life. Cosyntropin injection increased salivary cortisol concentration (an indicator of acute stress) but did not increase hair cortisol concentration. There was no evidence to suggest a significant effect of treatment on calf growth. Calf behavior was similar between treatment groups. These results suggest that the method used to activate the stress response system in this study was sufficient to induce an acute stress response in calves (as indicated by increased salivary cortisol concentration), and more research is needed to investigate measures of chronic stress in young dairy calves.

Read the full article in the Journal of Animal Science.