Laura Monclús

Acute ACTH-induced elevations of circulating cortisol do not affect hair cortisol concentrations in calves

In recent times, the detection of cortisol in hair is intended to be used as an animal-based indicator for the assessment of chronic stress. However, the relationship between the ability to report average values of long-term circulating cortisol concentrations and the sensitivity to acute peaks of cortisol is still unclear. To gain insight into this relationship, 24 Holstein-Friesian bull calves under the same management conditions were used in this study. Two injections of ACTH (at D0 and D7) were administrated to twelve animals with the aim to create two acute increases of serum cortisol concentrations. Blood samples were taken in order to determine the duration of serum cortisol peaks and to confirm a mediated response by the administration of ACTH. Cortisol concentrations from 14-day-old white hair samples collected from forehead and hip were analysed separately by EIA and compared with those from the control group. Serum cortisol analyses revealed an acute increase of cortisol concentrations for approximately three hours after each ACTH administration. Concentrations of hair cortisol from forehead and hip locations showed no differences between ACTH-administrated and control animals. Hair cortisol concentrations from 14-day old samples were not altered by two acute elevations of serum cortisol suggesting that hair cortisol is not masked by short and non-recurrent moments of stress. These results are a step forward in the validation of hair cortisol detection as a robust integrative measure of serum cortisol concentrations from an extended period of time.

Relationship between feather corticosterone and subsequent health status and survival in wild Eurasian Sparrowhawk

AbstractIn birds, integrated levels of corticosterone (CORT) measured in feathers (CORTf) allow us to make inferences on past levels of stress demands. It has been suggested that levels of CORTf track carry-over effects across seasons. Nevertheless, our understanding of how this measure can be used to assess future health status is far from complete. In this study, we aimed to investigate whether CORT deposited in feathers over the moulting period was related to subsequent mortality and health status in wild raptors admitted to rehabilitation centres. Thirty-four Eurasian Sparrowhawks (Accipiter nisus) admitted during the non-moulting period were sampled. Body condition (BC) was used as an indicator of health status to classify individuals’ health as good, poor or cachexia depending on their pectoral muscle score. Mortality was recorded over the non-moulting period. Other potential sources of CORTf variation were assessed, such as sex, age and feather type, primary or body covert feathers. While CORTf did not vary with age or sex, significant differences were found between primary and body feathers, highlighting the importance of sampling the same feather type. Our results also revealed that birds in poor BC showed higher CORTf levels than individuals in good condition; however, CORTf levels in cachectic birds did not differ from those in good condition. This finding suggests caution when assuming that only high CORTf levels represent individuals in poor condition, and limits the utility of CORTf for the prediction of BC. The present study also showed that individuals which died following admission had higher CORTf levels than individuals which survived, suggesting the potential utility of CORTf as a metric for the study of subsequent mortality.ZusammenfassungZusammenhang zwischen Feder-Kortikosteron und späterem Gesundheitszustand und Überleben bei Europäischen Sperbern Der Messung von Kortikosteron in Federn (CORTf) erlaubt Rückschlüsse auf vergangene Stresssituationen. Es werde angenommen, dass über CORTf-Spiegel Carry-over Effekte über die Zeit hinweg verfolgt werden können. Gleichwohl ist unser Verständnis, wie solche Werte zur Abschätzung des zukünftigen Gesundheitszustandes genutzt werden können bei Weitem nicht vollständig. Ziel dieser Studie war zu untersuchen, ob in Federn zur Mauserzeit eingelagertes Kortikosteron (CORT) mit späterer Mortalität und dem Gesundheitszustand von Sperbern, die in Greifvogelauffangstationen eingeliefert wurden, zusammenhängen. Dazu beprobten wir 34 außerhalb der Mauserperiode eingelieferte Europäische Sperber (Accipiter nisus). In Abhängigkeit vom Brustmuskelwert wurde die individuelle Gesundheit als gut, schwach oder abgemagert klassifizieren. Zudem wurde die Sterblichkeit über die Nichtmauserzeit ermittelt. Andere potentielle Quellen für Unterschiede im CORTf wie bspw. Geschlecht, Altern und Federtypen, Großgefieder oder Körperfedern wurden ebenfalls berücksichtigt. Während CORTf nicht mit Alter und Geschlecht variierte, wurden signifikante Unterschiede zwischen Groß- und Körpergefieder gefunden, was die Bedeutung der Beprobung desselben Federtyps hervorhebt. Unsere Ergebnisse zeigen auch, dass Vögel mit schlechter Kondition höhere CORTf Werte zeigten als Individuen in guter Kondition, wobei aber die CORTf Werte abgemagerter Vögel sich nicht von denen in guter Kondition unterschieden. Dieses Ergebnis unterstreicht die nötige Vorsicht, wenn angenommen wird, dass nur hohe CORtf Werte für Individuen mit schwacher Kondition stehen und reduziert gleichzeitig die Nützlichkeit von CORTf zur Vorhersage von Körperkonditionen. Die vorliegende Studie zeigt auch, dass Individuen, die später starben, höhere CORTf Werte hatten als Individuen, die überlebten, was zeigt, dass Federkortikosteron als ein Maß für spätere Mortalität verwendet werden kann.

Prediction of Cortisol and Progesterone Concentrations in Cow Hair Using Near-Infrared Reflectance Spectroscopy (NIRS):

Concentrations of different steroid hormones have been used in cows as a measure of adrenal or gonadal activity and, thus, as indicators of stress or reproductive state. Detecting cortisol and progesterone in cow hair provides a long-term integrative value of retrospective adrenal or gonadal/placental activity, respectively. Current techniques for steroid detection require a hormone-extraction procedure that involves time, several types of equipment, management of reagents, and some assay procedures (which can also be time-consuming and can destroy the samples). In contrast, near-infrared reflectance spectroscopy (NIRS) is a multi-component predictor technique, characterized as rapid, nondestructive for the sample, and reagent-free. However, as a predictor technique, NIRS needs to be calibrated and validated for each matrix, hormone, and species. The main objective of this study was to evaluate the predictive value of the NIRS technique for hair cortisol and progesterone quantification in cows by using specific enzyme immunoassay as a reference method. Hair samples from 52 adult Friesian lactating cows from a commercial dairy farm were used. Reflectance spectra of hair samples were determined with a NIR reflectance spectrophotometer before and after trimming them. Although similar results were obtained, a slightly better relationship between the reference data and NIRS predicted values was found using trimmed samples. Near infrared reflectance spectroscopy demonstrated its ability to predict cortisol and progesterone concentrations with certain accuracy (R2 = 0.90 for cortisol and R2 = 0.87 for progesterone). Although NIRS is far from being a complete alternative to current methodologies, the proposed equations can offer screening capability. Considering the advantages of both fields, our results open the possibility for future work on the combination of hair steroid measurement and NIRS methodology.

Cortisol detection in fish scales by enzyme immunoassay: Biochemical and methodological validation

The study of fish stress is usually assessed by measuring blood cortisol. Nevertheless, blood provides only a snapshot of the hormonal profile at one point in time. An alternative source of cortisol may be found in scales, providing a new approach for assessing long-term hormonal levels. The present study aimed to develop and validate a methodology for detecting cortisol in scales of goldfish (Carassius auratus). The study highlights the importance of an initial isopropanol washing procedure to completely eliminate external contaminations of cortisol. Additionally, the biochemical validation of the enzyme immunoassay verifies the ability to detect cortisol with repeatability and reliability in goldfish scales. In conclusion, this study provides validated information about a new methodology to measure cortisol in scales. The incorporation of this biomarker could provide retrospective hormonal measurements from species and time periods that are usually difficult or impossible to obtain, thus offering key data of an animal’s physiology. Journal of Applied Ichthyology

Costs of breeding are rapidly buffered and do not affect migratory behavior in a long‐lived bird species

Life history theory states that individual fitness in one stage of life is conditioned by what occurred in previous stages. In migratory species, reproductive effort during breeding has often been found to influence body condition, molt schedule, self-provisioning and migration of individuals in subsequent seasons (i.e., carryover effects of breeding). However, there is a current uncertainty in understanding how long-distance migrants trade off among such energy-demanding activities (i.e., breeding, molting and migrating). To provide evidence to the field, we experimentally reduced the parental effort of a long-lived Procellariform, the Corys shearwater (Calonectris borealis), by inducing failure at the incubation stage. Treatment and control birds were tracked during their subsequent migration by means of light-level and immersion loggers and sampled for six specific feathers (molted at different periods along the migratory cycle) upon the recovery of the loggers 1 yr later. Feathers were used to perform stable isotope analysis (SIA) and determine corticosterone levels (CORT). By these means, we evaluated the effect of breeding effort on migratory strategy, at-sea activity patterns, molt patterns, and levels of stress experienced by birds along the non-breeding period. We did not detect any difference between birds in the induced failure group and successful breeders in terms of spatio-temporal distribution: all birds shared common foraging areas throughout the study period and the timing of major phenological events did not differ. Failed birds significantly advanced their molt, as revealed by SIA and flying activity patterns. The stress levels of failed birds, inferred through CORT concentrations in feathers, were found to be consistently lower than in successful breeders, through the end of the breeding to the non-breeding period. Thus, we provide robust evidence that the costs of reproduction can be physiologically mediated from the breeding to the non-breeding period through molting schedules and CORT levels. However, we failed to detect clear effects on migratory behavior or subsequent breeding success, suggesting that costs of breeding in long-lived species may be rapidly buffered during the post-breeding period, as would be expected from life history theory.

Daily salivary cortisol levels in response to stress factors in captive common bottlenose dolphins (Tursiops truncatus): a potential welfare indicator

DOLPHINS in a captive setting can be occasionally subjected to a variety of potentially stressful situations. The stress response comprises a variety of biological reactions to internal or external stimuli elicited when an individual perceives (real or not) a threat to its homoeostasis (Moberg and Mench 2000). The stress response is a complex interplay of behavioural and physiological strategies to cope with changes in the environment (Tsigos and Chrousos 2002, Sheriff and others 2011). Noise can act as a stressor to dolphins because cetaceans rely heavily on sound for many important life functions. This reliance on sound means it is quite likely that exposure to noise will have some detrimental effects on these life functions (Wright and others 2007). Observed effects of noise on marine mammals include: changes in vocalisations, respiration, swim speed, diving and foraging behaviour; displacement; avoidance; shifts in migration path; stress; hearing damage and strandings, but responses of marine mammals to noise can often be subtle and barely detectable (Weilgart 2007). If there is no obvious change in behaviour, stress is difficult to assess in dolphins, both individually and as a group. In order to detect the presence of stress responses in these situations, the endocrine response to stressors is assessed evaluating the hypothalamic–pituitary–adrenal (HPA) axis activity in dolphins and other cetaceans (Wright and others 2007, Amaral 2010). The HPA axis is a key element of the stress response and, when activated, the resultant hormonal cascade increases the levels of glucocorticoids (GCs) …