Biomedical Engineering Reference
In-Depth Information
the opportunity for other animals to benefit from the
enrichment activity. When presenting foraging enrichment
opportunities for many animals within a group, multiple
devices should be provided to reduce the chance for
monopolization.
useful as enrichment for zoo-housed orangutans (
Tarou
et al., 2004
).
Assessing the Value of Enrichment
Enrichment should be empirically evaluated on a regular
basis to determine if it is achieving its intended goals.
There are several ways to assess the efficacy of enrich-
ment. One common method is to directly examine the
behavior of the subjects. Effective enrichment opportuni-
ties should result in increased levels of species-typical
behaviors, such as social grooming, foraging, and playing,
while simultaneously resulting in decreased levels of
abnormal behaviors. Abnormal behaviors include behav-
iors that do not occur in wild conspecifics and behaviors
that occur at abnormal levels in captive NHPs (compared
with their counterparts in the wild) (
Poole, 1988
). For
instance, self-injurious behavior is virtually absent in wild
primates. While self-grooming occurs in wild populations
of rhesus, it is unlikely to comprise 20
Occupational Enrichment
Occupational enrichment provides opportunities for the
primates to obtain physical and/or mental stimulation and
includes exercise and cognitive tasks. Exercise can be
provided by housing animals in large outdoor groups
(e.g. corrals) with species-appropriate furnishings or by
providing access to exercise cages for NHPs living in
smaller enclosures (
Storey et al., 2000
). Exercise or activity
cages are commercially available or can be modified from
existing cages. Additionally, many macaque species
interact with water sources in their natural environments,
and therefore, providing water in pools, tubs, or tanks can
be utilized as occupational enrichment (
Robins and Waitt,
2011
).
Cognitive tasks involving computers or related tech-
nology are often used to collect data for hypothesis-driven
psychological studies but can in certain circumstances be
used for enrichment as well (
Fagot and Paleressompoulle,
2009; Fagot and Bonte, 2010
). Primates can respond to
satisfy the experimental criteria, but they may also be able
to respond freely on the same or similar equipment, thus
providing them with the opportunity to control various
aspects of their treatment, one of the primary advantages of
occupational enrichment. Computerized tasks can provide
many enrichment opportunities, including “games” in
which the subject uses a joystick to move the computer's
cursor into a specific part of the screen to get a reward (
Platt
and Novak, 1997
). These kinds of experimental procedures
can be viewed as enrichment opportunities when they
provide a sense of control and choice. On the other hand,
tests in which the animals are water or food restricted may
not be enriching to the animals (
Prescott et al., 2010
). In
order to truly determine whether these sorts of tasks are
enriching to the animal, the behavior of the animal should
be carefully documented and evaluated.
Compared with the number of studies on other forms of
enrichment, relatively few empirical studies have evaluated
the efficacy of occupational enrichment. Access to exercise
has been shown to reduce behavioral problems in a variety
of species. Activity cages have also been shown to reduce
abnormal behaviors, such as stereotypy (
Storey et al.,
2000
). However, many of the behavioral problems returned
once the animals were placed back in their home cage.
Computer tasks have been found to influence levels of
stereotypies and other behavioral problems in rhesus and
bonnet macaques (
Washburn and Rumbaugh, 1992;
Lincoln et al., 1995; Platt and Novak, 1997
) and may be
30% of a wild
rhesus' activity profile as it may among singly caged
rhesus monkeys.
Additionally, one can examine indirect indicators of
behavior. For example, if an animal is presented with
enrichment (e.g. a grooming board) that is intended to
provide alternative activities to over-grooming, one can
simply monitor the quality of the hair coat (e.g.
Runeson
et al., 2011
) rather than directly investing the time neces-
sary to observe an increase in enrichment use and/or
a decrease in self-grooming behavior. The same type of
approach may be applied to enrichment strategies designed
to minimize self-injurious behavior (e.g. look for fewer
wounds).
Another way in which we can assess the value of
enrichment is to evaluate physiological parameters, such as
cortisol, heart rate, and immune function. Effective
enrichment opportunities should result in animals that
exhibit fewer physiological responses that are indicative of
the adverse consequences of stress (see Chapter 7). It may
be valuable to focus such assessment efforts on the physi-
ological indices that are most relevant to the experimental
role of the animal. For instance, if an animal is to partici-
pate in an experiment that assesses cell-mediated immune
responses, it would be appropriate to assess the effects of
enrichment on those same parameters (
Schapiro et al.,
2000
).
Finally, we can let the animals demonstrate the value of
enrichment opportunities. This can be done through choice
tests in which the primates are provided with various
options and can choose whether or not they want to
participate. Such choice tests are rare but can provide
important information. In one such test (
Crockett et al.,
1997
), adult M. fascicularis were trained to open a solid
panel to gain access to grooming-contact panels. Males in
e
