Body Weight and Faecal Corticosterone Metabolite Excretion in Male Sprague-Dawley Rats Following Short Transportation and Transfer from Group-housing to Single-housing
Body weight and faecal excretion of corticosterone metabolites (CM) were recorded daily in 18 young male Sprague-Dawley rats from the day they arrived at the animal facility from the breeder. The animals were group-housed (n=3) and divided in two groups after 7 days. One group (n=9 animals in 3 cages) was moved to another room in the facility and the other group remained in the original holding room. After an additional 7 days the animals which had been moved were separated and single housed for an additional 7 days. The body weights developed normally in all rats during the three-week period. Faecal CM excretion appeared high immediately after the rats arrived from the breeder, and decreased to reach significantly lower levels 6 days after arrival. This was likely related to natural fluctuations in faecal CM output rather than substantial stress. None of the husbandry procedures performed during the study had any effect on faecal corticosterone metabolite secretion compared to control. The results suggest that neither transportation from the breeder, moving within the facility, nor being transferred from group housing to single housing are events stressful enough to be reflected by the parameters analysed in the present study. However, the faecal CM excretions clearly fluctuate over several days, which must be considered when using faecal samples for non-invasive stress assessment.