Short communication: Is hair cortisol a potential indicator for stress caused by chronic lameness in dairy cows?

ABSTRACT The objective of this study was to evaluate hair cortisol concentration as an indicator for stress caused by chronic lameness in dairy cows. Sixty-eight cows were scored for lameness for 4 consecutive weeks. The hair of the tail switch was clipped at the beginning of the study and regrown hair was clipped after 4 wk. Hair samples were analyzed for cortisol concentration. Animals with 2 consecutive locomotion scores ≥3 or with an overall mean score >1.5 were classified as lame. After pair matching lame and nonlame cows, considering days in milk, lactation number, and milk yield, and excluding cows with less than 20 mg hair sample for analysis, 21 lame and 21 nonlame cows were included in the analysis. The mean hair cortisol concentration in this study was 2.32 ± 0.35 pg/mg (mean ± standard deviation). Cortisol concentration from hair regrown in the study period was 2.38 ± 0.95 and 2.26 ± 1.35 pg/mg for lame and nonlame cows (n = 21), respectively; we found no difference in mean cortisol level of primiparous and multiparous cows. Based on these data, hair cortisol concentration was not a useful indicator to differentiate cows with chronic lameness and healthy cows.