Scientific methods for assessing stress in livestock have advanced from simple cortisol measurement to multi-parameter approaches capturing acute and chronic stress dimensions.
Livestock stress assessment has evolved from single-biomarker approaches prone to confounding (any handling produces cortisol elevation) toward multi-parameter composite assessments that distinguish acute from chronic stress and physiological from behavioral dimensions. This matters practically because different welfare challenges produce different stress signatures - chronic hunger produces different patterns from acute fear, which produces different patterns from social conflict. Non-invasive methods like fecal cortisol and infrared thermography are particularly valuable because they allow welfare assessment without the welfare cost of sampling procedures. The development of automated continuous stress monitoring using wearable sensors represents a further advance, enabling longitudinal welfare tracking in commercial herds without repeated costly sampling.