Development of laboratory housing conditions preventing stereotypic behaviour in Mongolian gerbils (Meriones unguiculatus)
Duration: 3 years Project Completion: 2000
Background and Aim
Method and Results
1. Stereotypic digging develops under standard housing conditions when juvenile gerbils are motivated to retreat into a burrow but cannot do so. An artificial burrow consisting of a darkened nest chamber outside the cage, accessible through a tunnel at the back of the cage, significantly reduced stereotypic digging in juvenile gerbils. The same burrow structure, not darkened and presented within the cage, however, failed to reduce stereotypic digging in juvenile and adult gerbils. Up to this point, no correlation was found between the measured fecal cortisol levels (ranging from 80-120 ng/mg feces dry matter) and age, housing conditions or stereotypy. An artificial burrow system was developed which significantly reduces the development of stereotypic digging and can easily be integrated in a standard laboratory cage type 4, covering one third of the available space. It consists of an opaque nestbox with angled access tube, a transparent separation wall and for stability reasons of an additional, transparent box accesible through a hole.
2. Bar-chewing cannot be viewed as a replacement activity caused by a lack of chewable nesting material nor does it result from reinforced bar-manipulation caused by the vicinity of food pellets and cage-lid bars in the food hopper. Neither the presence of nesting material (straw, paper towels) nor the location of the food, whether contained in the food hopper or scattered on the bedding, had an influence on the duration of bar-chewing. A significant rise in bar-chewing occurred after juvenile gerbils were separated from their families at the age of 35 days and transferred to a similar cage with fresh bedding in same-sexed littermate pairs. High levels of bar-chewing then persisted up to adulthood. This rise in bar-chewing might reflect the animals’ motivation to return to their families and home cages. We tested whether social separation from the family or transfer to a new cage caused the rise in bar-chewing. A significant rise in bar chewing occured in groups that were separated from their family before younger siblings are born. Transfer to a new cage had no significant influence on the development of bar-chewing. These results imply that laboratory gerbils should not be prematurely separated from their parents, at least not until a new litter of young siblings is born.
Conclusions and Relevance for 3R
2. Waiblinger E. (2002): Comfortable Quarters for Gerbils in Reserach Institutions. In: Comfortable Quarters for Laboratory Animals (Ed. V. Reinhardt and A. Reinhardt), Animal Welfare Institute, Washington, DC 20007; Ninth Edition, 2002 (ISBN 0-938414-02-X); p.18 - 25. siehe auch: http://www.awionline.org/pubs/cq02/cqindex.html.
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4. Waiblinger E. and König, B. (2004), Refinement of gerbil housing and husbandry in the laboratory, ATLA 32; Supplement 1, 163-169.
4. Waibllinger E., König, B., Müller, L. and Schmid, H. (in prep): An artificial burrow system preventing the development of the digging stereotypy in laboratory gerbils, Animal Welfare.
5. Waiblinger, E. (in prep): Stereotypic digging and bar-chewing in laboratory gerbils - a test case for the current stereotypy definition? Applied Animal Behaviour Sciences.