The Ability of SD-Rats to Distinguish Between Three Different Housing Environments

Since 1986, when the Council of Europe gave the first provisions for housing of laboratory animals, the focus on housing conditions has increased with emphasis on the size of primary enclosures such as cages or pens as well as the complexity of the enclosure. Today European legislation dictates the minimum amount of enrichment to be present in cages for different species. The aim of this study was to evaluate the influence of different enrichment schemes on growth rate, water consumption, muscle strength and preference in rats, after items such as hides, nesting material, increased cage height and shelves had been introduced to the cage environment. The study demonstrated that rats spend more time in the extra-enriched cages compared to the non-enriched cages, whereas no differences in the dwelling time between the two types of enriched cages could be detected. When present in the cage, the built-in shelf was used extensively (over 40% of the observations) although no specific preference for the extra-enriched cage was detected. No differences in weight gain and water consumption could be detected between rats in the three different housing conditions, although there was a slight increase in muscle strength for the standard-enriched housed rats.