Johnson, S. R., Patterson-Kane, E. G. 2003. Foraging as environmental enrichment for laboratory rats: A theoretical review. Animal Technology and Welfare 2, 13-22.

Foraging opportunities are a form of environmental enrichment with great potential to improve the welfare of animals in laboratories. Though commonly used with zoo animals, little evidence exists of their use in laboratories. Technicians or other laboratory staff are unlikely to use foraging enrichment due to the lack of empirical and theoretical evidence supporting its use in the laboratory. This review demonstrates that relevant theoretical evidence does exist in the areas of foraging ethology, optimal foraging theory, contrafreeloading, and foraging enrichment with other species. The review reveals that foraging behaviours are an important part of the rat's behavioural repertoire and that these behaviours are restricted in the standard laboratory cage. In addition, rats have a 'need to forage', such that they forage even when it is not necessary to acquire food. Previous studies on foraging enrichments with other species demonstrate the success of foraging enrichment in improving welfare. These four areas of infrmation suggest that foraging enrichment can provide laboratory rats with the opportunity to perform natural behaviours and improve their psychological and physical health. Scattering food, giving access to whole food pellets and providing variable food types would be basic options to start with for making food more interesting.