Abstracts (first author)
Alteration of HPA/HPG axis reactivity as a consequence of chicken domesticationPDF
Domesticated animals can serve as models to study evolutionary processes. The hormonal stress responses of wild and domesticated animals have rarely been thoroughly compared. The Red Jungle fowl (RJF) is considered to be the main ancestor of all domesticated chicken breeds. The aim of this study was to investigate the impact of domestication on behaviour and reactivity of HPA/HPG axis to a stressful physical restraint episode. Using liquid chromatography tandem mass spectrometry methods (LC-MS/MS), plasma concentrations of 5 classes of steroids, namely, pregnanes, progestines, androgens, estrogens and glucocorticoids were measured at basal level, 10 and 60 minutes after restraint in domesticated female White Leghorn (WL) and RJF. In behaviour tests, WL had a slower stress recovery, whilst RJF resumed baselines in behaviour more quickly. Corticosterone level was significantly influenced by the stressor (p ≤ 0.001) in both breeds. RJF had significantly higher acute stress response (p ≤0.05) but quicker stress recovery compared to WL. In RJF, most other hormones were not influenced by the stressor while they were mostly significantly affected in the domesticated WL. Among the hormones which were differently altered in WL and RJF, dehydroepiandrosterone (DHEA), an androgen which is also involved in social and aggressive behaviour in birds, showed the most pronounced breed difference (p ≤ 0.005) and response to stress (p ≤ 0.001) in WL and might be highlighted as an important hormone in relation to both stress and domestication of chicken. To our knowledge this is the first comprehensive study, investigating the impact of stress on behaviour and a wide range of steroid and neurosteroid hormones in any domesticated animal and it´s wild ancestor. In conclusion, our study shows that the domesticated phenotype in chicken is related to lower HPA axis reactivity and higher HPG axis activity, which cannot be maintained in stressful situations.