Validated stress biomarkers including cortisol, heart rate variability and faecal glucocorticoids enable objective welfare assessment across species.
Stress biomarkers provide objective, quantifiable welfare assessment that complements behavioural observation. They are particularly valuable for demonstrating welfare impacts that are not visually obvious and for comparing welfare between systems or interventions in controlled studies. Non-invasive methods including faecal glucocorticoids and infrared thermography are especially valuable as they avoid the welfare cost of blood collection. Investment in species-specific validated biomarker ranges is a welfare research priority.