Module 07 - Environmental Enrichment

Opportunities to Occupy Time During Waking Hours

Searching for food, gathering nesting materials, play, travel, exploration, etc., are all activities that help pass the time.  The environment of many cages does not allow much of this to occur.  The highly nutritious food provided allows animals to consume their daily needs with very little effort.  Monkeys that work for their food waste less than those with easy access to it.  While commercially available foods are processed to contain all the elements that an animal requires, they may be low in palatability and certainly in variety.  It is possible to vary the diet for most experimental animals without imposing yet another variable on the study by providing small amounts of treats.  These treats provide additional tactile, olfactory, and taste stimuli. 

Cage equipment, nesting material, etc., allows the animal to interact with and in some cases manipulate their environment.  The equipment or material in the cage should be appropriate for the animal's behavioural needs.  Perches for birds, for example, should be the correct size or in a variety of sizes so that the birds can pick the most comfortable one for them.

Animals are sometimes given toys to play with but the toys should have some relevance to the animal or it will soon be neglected.  Some animals, e.g., rats, may not like new toys, especially if they have no apparent function for the animal and the toy may be buried.  The unpredictability of another animal may provide the majority of the diversion required to prevent the development of stereotypies that often develop when there is nothing to do.  Rats have been shown to work harder to gain access to another rat than to gain access to their favourite toy.

Exploratory behaviour is an important component of the daily routine for many young animals, particularly rodents.  This activity is often studied in rats and it is recognized that there are clear behavioural differences between rats that have had the opportunity to explore, for example, in a complex environment and those that have been reared in a simple environment.  Rats that have been reared in the standard rat cage will stand up and look out when the top is removed.  They will rarely attempt to leave the cage.  On the other hand, rats that have lived in a complex environment will take the opportunity to explore the room if the cage is left open.