Stress, Wool Cortisol, and Wool Quality: An Investigation of Seasonal Wool Cortisol Levels and Wool Quality Traits in Extensively Managed Merino Ewes
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Authors
Davies, Morgan
Issue Date
2025
Type
Thesis
Language
en_US
Keywords
Cortisol , Sheep , Stress Phenotype , Wool
Alternative Title
Abstract
Climate change, shifting consumer expectations, and a growing global populationare exerting unprecedented pressures on livestock production systems. This thesis
examines the physiological stress response of extensively managed Merino ewes, utilizing
wool cortisol concentrations as a biomarker, and assesses its relationship with wool quality
traits and reproductive performance. Wool samples from 111 Merino ewes were collected
and segmented to represent four critical production timepoints: lambing, turnout, early
breeding, and mid-gestation. Cortisol was extracted from wool segments and quantified via
enzyme-linked immunoglobulin assay. Wool segments were found to have variable levels
of cortisol, demonstrating a downward trend corresponding with the yearly production
cycle. The highest cortisol level was observed at lambing, and the lowest during mid-
gestation. Elevated cortisol levels were correlated with reduced fiber diameter, i.e.,
increased fineness, indicating that stress may alter wool quality. These findings offer
practical implications for improving welfare and production outcomes in sheep managed
under extensive conditions.