Validation of Fecal Glucocorticoid Metabolites as Non-Invasive Markers for Monitoring Stress in Common Buzzards (Buteo buteo)

For wild animals, being in captivity in wildlife centers can cause considerable stress. Therefore, it is necessary to establish and validate non-invasive tools to measure chronic stress during rehabilitation. Eight Common Buzzards which lived in permanent husbandry were placed individually into prepared aviaries and their feces were collected before, during and after a stress event for biological validation over a period of seven days. The extracted fecal glucocorticoid metabolites (fGCMs) were analyzed with three different enzyme immune assays (EIA) to find the most suitable one. Additionally, we aimed to investigate the stability of fGCM levels after defecation because further metabolization by bacterial enzymes can lead to changed results. The Cortisone-EIA performed best in males and females and showed that the stress event led to an fGCM increase of 629% (557% in females and 702% in males) in relation to basal values. We found no significant differences between the sexes, but observed significant differences between different times of day. FGCM concentration significantly changed after eight hours at room temperature. Our study successfully validated the non-invasive measurement of fGCM as a stress indicator in Common Buzzards and could therefore lay the foundation for future studies providing new insights for animal welfare research in Buzzards.

Non-invasive monitoring of adrenocortical function in female domestic pigs using saliva and faeces as sample matrices

Intensive pig management involves in a commercial setting the housing and implementation of certain procedures, such as castration and tail docking, which may be stressful for the animal. Good farming practices include the reduction of stress due to management processes, but assessing the level of stress perceived entirely through behavioural observations can be challenging. The monitoring stress-related physiological markers, like glucocorticoids (GC), can be an accurate alternative that would presumably be more objective. In order to avoid an additional stressor by taking blood, a non-invasive approach is advisable. We used an adrenocorticotropic hormone (ACTH) stimulation test and the effect of transport to examine the suitability of different enzyme immunoassays (EIAs) for monitoring adrenocortical function in domestic pigs using saliva and faeces as sample matrices. An assay measuring faecal glucocorticoid metabolites (fGCMs) with a 3ß,11ß-diol group has proven suited to determine adrenocortical activity, showing an overall increase of 180% in fGCM concentrations related to ACTH administration and of 70% related to transport, respectively. A cortisol EIA was used to detect salivary glucocorticoid (sGC) concentrations, revealing a 1100% increase in sGC concentrations after ACTH administration. The stability of fGCM concentrations post-defecation was determined to assess possible changes in measured fGCM concentrations in unpreserved faecal material over time, with fGCM concentrations being relatively stable (maximal 12% change) under natural conditions for approximately two days after defecation. This implicates that untreated faecal material from pigs can be analysed for up to two days after collection without appreciable level of depreciation in fGCM concentrations. Being able to assess the physiological stress response of domestic pigs non-invasively can help to improve the well-being of commercially reared pigs.

Impact of foot-and-mouth-disease on goat behaviour after experimental infection with serotype SAT1 virus

Infectious diseases and parasitic infestations can cause a set of non-specific clinical signs, such as increased body temperature and resting, and a decrease in food intake. These physiological and behavioural changes have an adaptive function facilitating defences against the pathogen and to support immune functions. These so-called' sickness behaviours' can also be used as an early detection tool for disease. Foot-and-mouth disease (FMD) still causes great economic losses in endemic countries, especially to smallholder farmers. The aim of this study was to determine if behavioural changes in goats can be used as an early indicator of FMD virus (FMDV) infection. The efficacy of a Southern African Territories (SAT) FMD vaccine was studied on forty South African indigenous goats. Changes in daily activities (resting, feeding, walking), as well as social behaviours (social resting, social feeding, dominance behaviours) were recorded and then compared over time and between clinically affected and unaffected goats. Pedometers were used to estimate average daily steps and to compare between groups of study animals. Eleven goats developed clinical signs of FMD, as well as non-FMD related sicknesses during the course of the study. Overall walking and resting behaviours were not significantly affected by the presence of FMD related clinical signs (p > 0.05). However, during the time of FMDV infection, social resting increased significantly (p < 0.001). Although goats developed FMD lesions on lips and tongues, percentage of time feeding was not affected (p = 0.762), suggesting that the study goats did not perceive the oral lesions as an important disturbance. Similarly, the number of steps did not consistently decrease in the presence of FMD-associated foot lesions. When affected by non-FMD related sicknesses, animals did not have an overall reduction in the time spent feeding (p = 0.867). However, goats affected with non-FMD conditions reduced the amount of social feeding (p = 0.002), potentially avoiding energetically costly competition at the feeding points. Overall, goats affected with FMD did not show more sickness behaviour, suggesting that FMDV infection in goats might not lead to obvious and therefore, easily detectable behavioural changes. This might have implications for farmers and animal health personnel, as individual goats infected with FMDV might be undetected within a flock due to the absence of obvious sickness behaviours, and the virus can therefore be spread more easily between herds through animal movements.

Noninvasive measurements of ovarian activity in Beira antelope (Dorcatragus megalotis)

As the natural habitat of more and more species becomes depleted, captive breeding programmes have become established to bring species back from the brink of extinction. Monitoring the reproductive status of an individual is essential in order to improve breeding success. Traditional methods have involved stressful blood sampling, and thus noninvasive methods have been proven to be reliable alternatives for monitoring reproductive function in both captive and free-ranging animals. Subsequently, noninvasive methods have become an invaluable tool in longitudinal studies and conservation efforts, as animals can be observed without, or minimal human contact. The Beira antelope is a small antelope endemic to the northern part of the Horn of Africa. Population numbers of the Beira have been declining over the last few decades due to habitat fragmentation. We show here that the reproductive cycle of female Beira antelopes can be monitored noninvasively, by using faecal samples to analyse oestrogen (fEM) as well as progestagen (fPM) metabolites. The profiles of fPM and fEM of both females showed regular cyclic patterns in which the follicular and luteal phases could be distinguished. The overall mean cycle length is 22 days (range: 21-25 days), with a mean length of the follicular phase of 6 days (range: 4-7 days) and a mean length for the luteal phase being 15 days (range: 12-16 days). The suitability of these noninvasive techniques should assist in optimizing breeding efforts of this endemic small antelope in captivity. Being noninvasive, this method could also be a useful tool for monitoring reproductive function in the dwindling wild populations.

The impact of age-class and social context on fecal glucocorticoid metabolite levels in free-ranging male giraffes

One of the primary sources of perceived stress is the social environment of an animal and the interactions with conspecifics. An essential component of the response to a stressor is the activation of the hypothalamic-pituitary-adrenocortical axis, which results amongst others in a temporal increase in circulating glucocorticoid (GC) levels. Giraffes occur in a highly flexible fission-fusion social system and group compositions can change on a daily basis, with bulls establishing an age-related dominance hierarchy and showing a roaming strategy in the search for fertile females. The aim of this study was to non-invasively monitor the influence of different group compositions (mixed sex groups vs. all-male groups) on GC concentrations in free ranging giraffe bulls of different age classes. We collected fecal samples from free-ranging giraffe bulls for 12months in a South African Private Game Reserve to examine age- and social context-related patterns of fecal GC metabolite (fGCM) concentrations. We found that fGCM levels in giraffe bulls are age-class dependent, as well asassociated with changes in the social environment. Independently of the social setting, bulls of the youngest age class exhibited the highest fGCM levels compared to bulls of the other two older age-classes, with differences most pronounced when the bulls are associated in all-male groups. In contrast, an almost reversed picture appears when looking at the fGCM levels of sexually active individuals in mixed sex groups, where highest levels were found for the bulls in the oldest age-class, and the lowest for the bulls in the youngest age-class. The study stresses the importance to taking factors such asage-related status and social settings into account, when interpreting fGCM levels in free ranging giraffes.

Age and socially related changes in fecal androgen metabolite concentrations in free-ranging male giraffes

In many mammal species, androgen levels in males are elevated during periods of mating activity, often to facilitate aggressive behavior between males over access to fertile females. However, this pattern might be less obvious in species with a rather low male-male aggression rate, or in those that are not strictly seasonal breeders. A complex social structure, as well as additional social and environmental factors, might add more to the complexity. Here, we applied a non-invasive method to monitor fecal androgen metabolite (fAM) levels in free-ranging giraffe bulls over a period of months to examine longitudinal patterns of androgen metabolite concentrations in relation to observed male sexual behavior in different age classes. Giraffes are non-seasonal breeders, living in a fission-fusion social system and males show a roaming strategy to search for fertile females. Our results show that season has an impact on fAM levels in free-ranging giraffes, with respective steroid concentrations being higher in summer. In the presence of females, fAM levels of bulls are significantly higher compared to when found in all-male groups, with old adult bulls showing the highest fAM levels. In contrast, young adult bulls have overall slightly higher fAM levels compared to old adult bulls when residing in all male groups. Sexual behavior increases fAM levels only in old adult bulls.

Fecal thyroid hormones allow for the noninvasive monitoring of energy intake in capuchin monkeys

Measuring energetic condition of wild animals is of major importance in ecological research, as it is profoundly linked to fitness. However, noninvasive monitoring of energetic condition in wild-living animals is methodologically challenging. Measuring urinary C-peptide levels is a suitable method to noninvasively assess energy balance in wild-living animals. As collecting urine is not always feasible in the wild, it is essential to establish alternative biomarkers for other sample types to assess energy balance. Thyroid hormones (TH) are potential candidates as they are involved in the regulation of metabolic processes. During periods of low energy intake, serum TH levels are reduced, leading to a decrease in metabolic activity. To investigate whether fecal TH can serve as a biomarker for energy balance, we validated a total T3 ELISA to measure immunoreactive T3 (iT3) in fecal samples of yellow-breasted capuchins. We restricted caloric intake of seven males, assessed daily group caloric intake and determined daily individual fecal iT3 levels. Analytical validation of the assay showed that fecal iT3 levels can be reliably measured; however, proper storage conditions must be implemented and possible degradation to be accounted for. IT3 levels were significantly higher on days with high group caloric intake. However, individual iT3 levels varied substantially, resulting in an overlap across individuals between conditions. Our results indicate that fecal iT3 levels can serve as a useful biomarker to detect changes in energy intake of yellow-breasted capuchins. Overall, measuring fecal iT3 levels may present a suitable method for monitoring energy balance when urine collection is impossible.