Non-invasive wool hormone assessment of Australian merino rams (Ovis aries): a pilot investigation of cortisol and testosterone

Abstract

Introduction: Non-invasive hormone assessment is growing in interest as producers and livestock researchers seek new methods to assess animal welfare. Non-invasive wool assessment offers long-term, historic reflections of hormone concentration at the scale of weeks and months - and are not limited by sampling stress - thus making wool an appropriate tissue for long-term hormone analysis. This pilot study quantified cortisol and testosterone concentrations of ram fleece and determined if there is a significant difference between segments of the sample staple, and whether there is a correlation between hormones. Cortisol is a glucocorticoid produced within the adrenal glands and secreted in anticipation of or in response to a stressor. Testosterone is an androgen mainly synthesised within the testes of males and responsible for several critical functions including regulation of muscle growth, libido and spermatogenesis. Methods: In our study, 70 topknot wool samples were collected from rams on a commercial stud property in Dirranbandi, Queensland, Australia. Of these animals, 12 samples were selected at random to undergo cortisol and testosterone quantification. In the laboratory, a single, intact staple was isolated from the total sample, divided into 10 mm segments and prepared for their respective (cortisol or testosterone) immunoassays. Results: No significant difference (p > 0.05) was found between wool segments for either cortisol or testosterone, however, statistical differences (p < 0.05) were found between individuals for both hormones. A strong positive correlation (R2 = 0.9173, p < 0.05) was found between wool cortisol and testosterone concentrations. Discussion: In summary, this study reveals the major future possibilities for non-invasive wool hormone assessment in merino rams.