Short Communication: Factors Affecting Hair Cortisol Concentrations in Lactating Dairy Cows

This study investigated factors affecting hair cortisol concentrations in lactating Holstein cows, focusing on hair color, sampling location, and processing method. It involved 18 cows for color and location analysis, 12 for growth rate measurement, and 37 for resampling intervals. Results showed that white hair had higher cortisol levels than black hair, with the tail switch hair having more cortisol than shoulder hair. Grinding samples with a ball mill yielded higher cortisol concentrations than cutting with scissors. The tail switch hair grew faster and was more responsive to cortisol changes, making it the preferred site for measuring hair cortisol in Holsteins. Multiparous cows showed higher cortisol levels, particularly shortly after calving.