Comparison of cortisol concentration in hair and faeces of dairy cows reared in organic farms

Cortisol is frequently used to detect changes in the activity of the hypothalamic-pituitary-adrenal axis (HPA), which in turn regulates many biological processes such as energy balance, reproduction or immune responses, but it is also activated by stress conditions. For many years, cortisol was measured primarily in blood, saliva or urine, whereas later approaches added other matrices as hair and faeces for non-invasive monitoring of HPA functioning. The aim of this study was to investigate on the cortisol concentration of dairy cows reared in organic farming system obtained from two different matrices: hair and faeces. The study involved 20 cows from two organic farms located near Florence (Mugello area). Samples of hair were taken from the tail switch and faeces were directly picked up from the rectum ampule. Hair cortisol extraction was performed according to the method described by Koren et al. (2002) modified by Accorsi et al. (2008) and determined by the RIA method described by Tamanini et al. (1983). Fecal cortisol extraction methodology was modified from Schatz and Palme (2001). Anova test was applied to check differences between hair ad fecal cortisol. Significant differences were observed between the two biological matrices (1,5 vs 1,0 respectively for hair and fecal cortisol), nevertheless the scored levels did not indicate a state of animal suffering.