Cortisol/dehydroepiandrosterone ratio in saliva: Endocrine biomarker for chronic stress in pigs?

摘要

The adrenal hormone dehydroepiandrosterone (DHEA) in contrast to cortisol is suggested as a chronic stress marker. The aim of the present orientation study was to test whether DHEA was different in 10-wk-old pigs reared with three different housing systems on different farms. Blood and saliva were taken from 71 pigs reared under either indoor conditions with low disease level (n = 30; I+) or indoor conditions with different welfare and health problems (caudophagia, infections, I-; n = 21) or under Unproved conditions (combination of indoor and outdoor areas, C; n = 20), aimed to enhance animal welfare, for instance by offering straw and abandonment of tail docking. In C pigs, serum cortisol was lower than in I+ (P 0.001), but similar to I-. In saliva, cortisol levels in pigs from C were lower compared to I+ and I- (P 0.001). Serum DHEA was lower in C pigs than in I- pigs (P = 0.017) and in I- pigs it was higher compared to pigs reared under I+ conditions (P 0.001). DHEA in saliva was higher in pigs from C compared to I+ pigs and I- pigs (P 0.001). In saliva, the piglets reared in C showed a lower cortisol/DHEA ratio compared to I+ pigs and I- pigs (P 0.001) which may indicate less stressors in the C system. Further research is needed to confirm these results and to show the importance of DHEA for the analysis of chronic stress in pigs.