Robert C. Coleman

Physiological stress in the Eurasian badger (Meles meles): Effects of host, disease and environment

A method for monitoring hypothalamic-pituitary-adrenal (HPA) responses of the Eurasian badger (Meles meles) to stressors was validated by measuring cortisol excretion in serum and faeces. Serum and faecal samples were collected under anaesthesia from live-captured, wild badgers and fresh faeces was collected from latrines at 15 social groups in County Down, Northern Ireland. Variation in levels of cortisol in wild badgers was investigated relative to disease status, season, age, sex, body mass, body condition and reproductive status and environmental factors that might influence stress. Faecal cortisol levels were significantly higher in animals testing culture-positive for Mycobacterium bovis. Prolonged elevation of cortisol can suppress immune function, which may have implications for disease transmission. There was a strong seasonal pattern in both serum cortisol, peaking in spring and faecal cortisol, peaking in summer. Cortisol levels were also higher in adults with poor body condition and low body mass. Faecal samples collected from latrines in grassland groups had significantly higher cortisol than those collected from woodland groups, possibly as a result of greater exposure to sources of environmental stress. This study is the first to investigate factors influencing physiological stress in badgers and indicates that serological and faecal excretion are valid indices of the HPA response to a range of stressors.

The impact of social context on behaviour and the recovery from welfare challenges in zebrafish, Danio rerio

Understanding how animals experience stress in a laboratory environment is crucial for improving their welfare. Increasing numbers of fish are being used in scientific studies and further research is required to ensure appropriate conditions are used to promote good conduct and correct housing as well as guaranteeing scientifically valid results. As zebrafish are a gregarious species, social enrichment is particularly important, with individuals separated from a group experiencing isolation stress. The present study aimed to determine the effects of social context on recovery from common laboratory procedures. Additionally, we investigated whether the noninvasive measure of water-borne cortisol can be utilized to gauge physiological stress by comparing it to an invasive measure, whole-body cortisol concentration. Zebrafish (AB strain, male) were housed in differing social contexts and were randomly assigned to one of three treatment groups: undisturbed, anaesthetized and handled, or anaesthetized and fin clipped. Behavioural and physiological stress indicators were recorded before and after treatment. The results indicated social context, in the form of group housing, was important in enhancing recovery from welfare challenges in zebrafish, since group-housed fish resumed normal behaviours more quickly than pairs or individuals. Moreover, the strong correlation between water-borne and whole-body cortisol suggests that the noninvasive measure is an appropriate ethical alternative as an indicator of physiological stress. These findings represent an important refinement in reducing the severity of stress through housing zebrafish in their original groups and by adopting a noninvasive measure of cortisol which will act to reduce the numbers of individuals required for time series studies on physiological stress.

Effects of transportation, transport medium and re-housing on Xenopus laevis (Daudin)

Understanding the immediate and longer-term effects of transportation and re-housing in a laboratory species is crucial in order to refine the transfer process, enable the optimal introduction of new animals to a novel environment and to provide a sufficient acclimatisation period before usage. Whilst consideration of animal welfare in most model vertebrate species has received attention, little quantitative evidence exists for the optimal care of the common laboratory amphibian Xenopus laevis. Techniques for the non-invasive welfare assessment of amphibians are also limited and here a non-invasive physiological assay was developed to investigate the impacts of transportation, transport medium and re-housing on X. laevis. First the impacts of transportation and transport medium (water, damp sponge or damp sphagnum moss) were investigated. Transportation caused an increase in water-borne corticosterone regardless of transport medium. Frogs transported in damp sphagnum moss also had a greater decrease in body mass in comparison to frogs not transported, suggesting that this is the least suitable transport medium for X. laevis. Next the prolonged impacts of transportation and re-housing were investigated. Frogs were transported between research facilities with different housing protocols. Samples were collected prior to and immediately following transportation, as well as 1 day, 7 days and 35 days after re-housing. Water-borne corticosterone increased following transportation and remained high for at least 7 days, decreasing to baseline levels by 35 days. Body mass decreased following transportation and remained lower than baseline levels across the entire 35 day observation period. These findings suggest the process of transportation and re-housing is stressful in this species. Together these findings have important relevance for both improving animal welfare and ensuring optimal and efficient scientific research.