Higher Faecal Cortisol Metabolites Research Articles

Faecal cortisol concentrations as indicator of stress during intensive fattening of beef cattle in a humid tropical environment.

The study evaluated the concentrations of faecal cortisol metabolites (FCM) in intensively fattened beef cattle from a feedlot in a humid tropical environment. A total of 360 bulls weighing 271-371kg were kept confined in pens from the start to the end of the fattening period (FP). At 24h after arriving at the feedlot, cattle were distributed into the pens according to their live weight: 271-320kg, 321-370kg, and >370kg. At the start of the FP, four pens of each weight group were randomly selected, and in each of them 10 faecal samples were obtained from 10 randomly selected bulls; this sampling was repeated in the same pens and in each weight group at the middle and end of the FP. The FCM were measured through enzyme immunoassay. The 271-320kg group had higher FCM at the end of the FP (P < 0.05), the 321-370kg group had similar FCM throughout the FP (P > 0.05), and the >370kg group showed higher FCM at the start and end of the FP (P < 0.05). Higher FCM were observed at the middle of the FP in the 321-370kg group, and at the end of the FP in the 271-320kg and >370kg groups (P < 0.05). Mean FCM obtained throughout the FP were within normal ranges for cattle, suggesting that appropriate management in feedlots in humid-tropical regions can provide bulls with a low-stress environment.

Climate-driven changes in diet composition and physiological stress in an arboreal folivore at the semi-arid edge of its distribution

Species, particularly foliovores, at the trailing edge of their geographical range are likely to be most vulnerable to climate change as they respond to physiological stress and the decline in the nutrient richness of their food source. We investigate the effect of environmental conditions on diet composition, resource use, and physiological stress of koalas (Phascolarctos cinereus) in the semi-arid landscapes of southwest Queensland, Australia, across three different biogeographic regions. Fresh faecal pellets were collected to measure cortisol metabolites and assess diet. Regression analyses were used to relate the diet composition and physiological stress of wild koalas to environmental variables. The impact of drought was apparent, with higher faecal cortisol metabolites (FCM) levels recorded during drought conditions compared with post-flood conditions. Diet composition also changed between drought and post-flood conditions, with diets during drought being mainly composed of species with high leaf-moisture content. Low minimum temperatures increased FCM concentrations, and these effects were greater during drought conditions. The results demonstrate the importance of integrating physiological assessments into ecological studies to identify stressors that have the potential to compromise the long-term survival of threatened species, as well as the need to identify the resources required for their continued survival.

Physiological stress in koala populations near the arid edge of their distribution.

Recent research has shown that the ecology of stress has hitherto been neglected, but it is in fact an important influence on the distribution and numbers of wild vertebrates. Environmental changes have the potential to cause physiological stress that can affect population dynamics. Detailed information on the influence of environmental variables on glucocorticoid levels (a measure of stress) at the trailing edge of a species’ distribution can highlight stressors that potentially threaten species and thereby help explain how environmental challenges, such as climate change, will affect the survival of these populations. Rainfall determines leaf moisture and/or nutritional content, which in turn impacts on cortisol concentrations. We show that higher faecal cortisol metabolite (FCM) levels in koala populations at the trailing arid edge of their range in southwestern Queensland are associated with lower rainfall levels (especially rainfall from the previous two months), indicating an increase in physiological stress when moisture levels are low. These results show that koalas at the semi-arid, inland edge of their geographic range, will fail to cope with increasing aridity from climate change. The results demonstrate the importance of integrating physiological assessments into ecological studies to identify stressors that have the potential to compromise the long-term survival of threatened species. This finding points to the need for research to link these stressors to demographic decline to ensure a more comprehensive understanding of species’ responses to climate change.

Behaviour and stress responses in horses with gastric ulceration

Only little is known about behaviour and stress responses in horses with gastric ulceration, despite the high prevalence of this condition. Our objectives in the present study was to (i) describe the severity of gastric ulceration in horses, housed under relatively standardised conditions, and (ii) to investigate whether horses with severe glandular gastric ulceration have increased baseline and response concentration of stress hormones and behave differently than control horses. We investigated stomachs of 96 horses at one stud, and compared an ulcer group (n=30; with severe lesions in the glandular mucosa) to paired controls (n=30; free from gastric ulcers). Baseline and response concentrations of faecal cortisol metabolites (FCM), heart rate and behaviour were measured in a novel object test (NOT, Day 1) and behaviour during postponed feeding (PF, Day 2). Glandular lesions occurred in 55.2% and non-glandular lesions in 40.6% of the horses. The amount of starch in the feed (P=0.006) and paternal stallion (P=0.031) influenced ulceration in the non-glandular region only; it should be noted that our study does not allow for separating hereditary from environmental influences, as offspring may be e.g. trained differently dependent on breeding line. Ulcer horses pawed more (P<0.001) and ate quicker (P=0.050) during PF. Although displayed by ulcers horses only during PF, we failed to demonstrate a significant association between glandular gastric ulceration and crib-biting/weaving; the total number of horses with these types of abnormal behaviour was low (n=5). Behaviour and heart rate did not differ between groups in the NOT. Baseline concentration of FCM was similar (P=0.79), however, ulcer horses responded stronger to novelty than controls (26% higher FCM; P=0.018). We conclude that the prevalence of gastric ulcers was high, and our results suggest different factors affecting ulceration in the glandular versus the non-glandular region of the horse stomach. Obvious external signs (e.g. poor body condition) identifying ulcer horses were absent. Horses with severe glandular ulcers had a higher stress hormone response to novelty, thus they were more stress sensitive. Consequently, management evoking stress in horses should be reduced to dampen the development of glandular ulceration, or to protect horses with this condition.

Effects of birth date and natal dispersal on faecal glucocorticoid concentrations in juvenile Common hamsters

In seasonally breeding animals, timing of reproduction in females can influence offspring development and survival. Temporal and energetic constraints are often more pronounced in juveniles born late in the season, and could activate the stress axis. Common hamsters (Cricetus cricetus) are hibernating rodents, and adult females produce up to three litters during the active season. Birth dates range from May to September, and shortly after natal emergence pups are weaned and start to disperse. In this study, we used faecal cortisol metabolites (FCM) as a non-invasive measure of recent glucocorticoid exposure. We compared FCM levels between early- (June/July) and late- (August/September) born juvenile Common hamsters during their first weeks after natal emergence. We further compared FCM levels in juveniles born in the study area and individuals that immigrated either early or late in the season. Additionally, we investigated potential effects of human disturbances on cortisol secretion patterns. FCM levels in late-born juveniles increased during the first weeks post-emergence and were significantly higher than those in early-born individuals during the post-weaning period. Late-immigrating juveniles had significantly higher FCM levels than early immigrants and residents during the same time period. Individuals that inhabited areas frequently used by humans had higher FCM levels than those in low-impact areas. These results indicate that the seasonal timing of birth and dispersal affect cortisol secretion patterns in juvenile Common hamsters. As all juveniles immerged into their hibernacula during early October, we assume that late-born and late-immigrated individuals have less time to prepare for hibernation. This could elevate energetic demands and increase exposure to predators and/or humans during food caching. These factors might lead to increased adrenal activity and thus, elevated FCM concentrations in these individuals. Potential consequences of these time constraints and associated physiological effects could be reflected in the lower overwinter survival rates of juveniles born late in the season.