Exploring hair cortisone concentration as a novel tool to assess chronic stress in sheep with tick-borne fever

Abstract

A B S T R A C TTick-borne fever (TBF), caused by the bacterium Anaplasma phagocytophilum and transmitted by the tick Ixodes ricinus, has considerable consequences for animal welfare and economy in the sheep industry. Non-invasive, objective methods to quantify chronic stress are needed in order to evaluate the welfare impact of disease. The aim of this study was 1) to evaluate hair cortisol (HC) and hair cortisone (HCn) as biomarkers of chronic stress in sheep with TBF and 2) to test whether there was an association between the development of TBF and concentrations of HC, HCn and faecal cortisol metabolites (FCM) and body weight. The experiment took place in an area with a high prevalence of TBF, and thirty lambs were used in the study. Wool samples were collected in Week 0, in Week 3 (before turn out on homeland spring pasture), in Week 6 (before turn out on summer rangeland pasture) and at the end of the summer (Week 15). Faecal samples were collected every week (ie. Week 0-6 and Week 15). Symptoms of TBF developed in 15 lambs, of which all recovered from the disease after treatment with antibiotics. HC levels decreased progressively, and significantly, between Week 0, 3, 6 and 15 (p < 0.001), while HCn only decreased from Week 0 to Week 3 (p < 0.001) and then remained stable between Week 3-15. FCM increased between Week 0 and 5 (p = 0.027), and a significant association was found between increased FCM levels in Week 5 and lambs developing clinical signs of TBF (p = 0.022). We also found an association between lambs developing clinical signs of TBF and elevated HCn levels in Week 6 (p = 0.013). A slightly lower weight gain at later time points (Week 6 and 15) were found in the affected lambs compared to clinically healthy lambs. Our results indicate local production and/or metabolism of glucocorticoids in the hair follicles. This study strengthens our previous finding of a potential merit of hair cortisone as a biomarker of chronic stress in sheep.

A New Approach to LCA Evaluation of Lamb Meat Production in Two Different Breeding Systems in Northern Italy

“…The absolute level in cortisol is comparable with previous studies ( 24 , 25 ). Age, in fact, is a factor that influences the levels of cortisol in the hair, as at the moment of birth or at a young age it is higher and decreases with the passage of time, something that is also observed in other farming species.…”

“…We evaluated the production and welfare parameters of lambs from birth to slaughter. In contrast to saliva and blood cortisol, studies in other species have shown that hair cortisol is a proxy measure to the total retrospective activity of the HPA-axis over weeks or even months ( 24 , 25 , 31 ). Our data show clearly that the hair cortisol was less accumulated during the extensive breeding despite the various activities and experiences that the animals undergo, which affects this parameter (daily motor activity along high altitude slopes, sudden climatic changes, and presence of predators).…”

Chronic elevation of plasma cortisol causes differential expression of predominating glucocorticoid in plasma, saliva, fecal, and wool matrices in sheep

“…Unlike plasma and saliva levels the fibre therefore provides a more stable measure of long term activation of the HPA axis. The finding of high levels of cortisone in the fibre is interesting and supportive of a previous observation of cortisone in wool (8,41). We speculate that the production of cortisone from cortisol by the enzyme 11βHSD2 takes place in the cells of the follicle bulb or, possibly, the root sheaths surrounding the growing fibre.…”

Using sensors to detect individual responses of lambs during transport and pre-slaughter handling and their relationship with meat quality

“…Within each system the comparison between the four-monthly times of the wool collection showed high levels of cortisol in the first month of life (T1) with a constant decrease in values over successive monthly periods of wool collection (T2, T3, and T4) in both systems (Figure 2[c]). These absolute levels of cortisol are comparable with previous studies (Stubsjøen et al 2015(Stubsjøen et al , 2018. Age, in fact, is a factor that influences the levels of cortisol in the hair, as at birth it is higher and decreases with the passage of time, something that is also observed in other farm animals.…”