Transient Treatment of Pregnant Merino Ewes with Modulators of Cortisol Biosynthesis Coinciding with Primary Wool Follicle Initiation Alters Lifetime Wool Growth

The study investigated the impact of transient manipulation of maternal cortisol levels on wool follicle development in Merino sheep. Pregnant ewes were treated with either metyrapone (a cortisol inhibitor) or betamethasone (a cortisol analogue) from Days 55–65 post-conception. Lambs exposed to metyrapone had hairier birthcoats, a 10% increase in staple length, and reduced crimp frequency for the first three shearings compared to controls (P < 0.05). Gene expression analysis showed up-regulation of genes involved in hair and skin development. The findings suggested that altering maternal cortisol during critical fetal development phases could result in long-term changes in wool characteristics, indicating potential for targeted therapeutic interventions to enhance wool production.