Guide for the Care and Use of Laboratory Animals - Office of ...

ENVIRONMENT, hOUSING, ANd MANAGEMENT 55changes when animals are first introduced to outdoor housing; training ofanimals to cooperate with veterinary and investigative personnel (e.g., toenter chutes or cages for restraint or transport); and adequate security via aperimeter fence or other means.Naturalistic EnironmentsAreas such as pastures and islands may provide a suitable environmentfor maintaining or producing animals and for some types of research. Theiruse results in the loss of some control over nutrition, health care and surveillance,and pedigree management. These limitations should be balancedagainst the benefits of having the animals live in more natural conditions.Animals should be added to, removed from, and returned to social groupsin this setting with appropriate consideration of the effects on the individualanimals and on the group. Adequate supplies of food, fresh water, and naturalor constructed shelter should be ensured.SpaceGeneral Considerations for All Animals An animal’s space needs are complexand consideration of only the animal’s body weight or surface areamay be inadequate. Important considerations for determining space needsinclude the age and sex of the animal(s), the number of animals to becohoused and the duration of the accommodation, the use for which theanimals are intended (e.g., production vs. experimentation), and any specialneeds they may have (e.g., vertical space for arboreal species or thermalgradient for poikilotherms). In many cases, for example, adolescent animals,which usually weigh less than adults but are more active, may require morespace relative to body weight (Ikemoto and Panksepp 1992). Group-housed,social animals can share space such that the amount of space required peranimal may decrease with increasing group size; thus larger groups may behoused at slightly higher stocking densities than smaller groups or individualanimals. Socially housed animals should have sufficient space and structuralcomplexity to allow them to escape aggression or hide from other animalsin the pair or group. Breeding animals will require more space, particularlyif neonatal animals will be raised together with their mother or as a breedinggroup until weaning age. Space quality also affects its usability. Enclosuresthat are complex and environmentally enriched may increase activity andfacilitate the expression of species-specific behaviors, thereby increasingspace needs. Thus there is no ideal formula for calculating an animal’sspace needs based only on body size or weight and readers should takethe performance indices discussed in this section into consideration whenutilizing the species-specific guidelines presented in the following pages.