Evaluation of different types of enrichment - their usage and effect on home cage behavior in female mice

PLoS One. 2021 Dec 23;16(12):e0261876. doi: 10.1371/journal.pone.0261876. eCollection 2021.

Abstract

Numerous studies ascertained positive effects of enriched environments on the well-being of laboratory animals including behavioral, physiological and neurochemical parameters. Conversely, such conclusions imply impaired animal welfare and health in barren husbandry conditions. Moreover, inappropriate housing of laboratory animals may deteriorate the quality of scientific data. Recommendations for housing laboratory animals stipulate that cages should be enriched to mitigate adverse effects of barren housing. In this context, it is not only unclear what exactly is meant by enrichment, but also how the animals themselves interact with the various items on offer. Focal animal observation of female C57BL/6J mice either housed in conventional (CON) or enriched (ENR) conditions served to analyze the impact of enriching housing on welfare related behavior patterns including stereotypical, maintenance, active social, and inactive behaviors. CON conditions resembled current usual housing of laboratory mice, whereas ENR mice received varying enrichment items including foraging, housing and structural elements, and a running disc. Active and inactive use of these elements was quantitatively assessed. CON mice showed significantly more inactive and stereotypical behavior than ENR mice. ENR mice frequently engaged with all enrichment elements, whereby riddles to obtain food reward and the running disc preferably served for active interactions. Offering a second level resulted in high active and inactive interactions. Structural elements fixed at the cagetop were least attractive for the mice. Overall, the presented data underline the positive welfare benefits of enrichment and that mice clearly differentiate between distinct enrichment types, demonstrating that the perspective of the animals themselves should also be taken into account when specifying laboratory housing conditions. This is particularly important, as the ensuring of animal welfare is an essential prerequisite for reliable, reproducible, and scientifically meaningful results.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Exploratory Behavior / physiology*
  • Female
  • Housing, Animal
  • Mice
  • Nesting Behavior / physiology*

Grants and funding

This study was funded by the Federal Institute for Risk Assessment, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.