Animal Welfare in the United states amended in 1985 to “require research laboratories to carry out provisions to promote “psychological well-being” of nonhuman animal primates.” Some methods used in order to implement and improve well-being suggested within the regulations included “provision of perches, swings, mirrors, manipulatable objects, and task-oriented feeding methods”(USDA 1991). The introduction of this act “represented the first legislative recognition [in this country] of the importance of environmental enrichment for animals.” Environmental enrichment were primarily, extensively studied by experimental psychologists in order to evaluate “the effects of enrichment during development on learning, social behaviour, and neuroanatomy and neurophysiology (Renner and Rosenzweig 1987) and in these studies , enriched environments were usually defined as “cages containing social companions in with stimulus complexity in increased by the addition of a variety of objects such as tubes, blocks, or plastic toys.” And these objects ore often interchanged frequently to ensure continuing novelty. 

 

However, when scrutinising modern laboratory zoo and agricultural animal housing, one may find it difficult “to discern what constitutes an “enriched” environment using a definition based primarily on complexity.” And many agricultural animals are kept in completely barren environments in which their “ability to make even normal postural adjustments is curtailed (Mench and van Tienhoven 1986)”. In particular, in preventing nursing sows from lying on and crushing piglets, the sows are often housed in narrow enclosures (farrowing crates) that disallows them from turning around. Similarly, veal calves and laying hens are also closely confined for reasons of both animal health and production efficiency. Therefore, by providing bedding materials i.e straws to crated sows or wood shavings to caged laying hens can be considered a crucial form of enrichment under these conditions (Fraser 1975). Consequently, “practical environment enrichment of captive animals is often defined in terms of its purpose rather than simply as a process or a phenomenon.” Chamove and Anderson (1989), for example, suggests that “enrichment should decrease abnormal behaviours, increase the behavioural repertoire, facilitate a more normal temporal patterning of behaviour, and enable the animal to cope with challenges in a normal way.” In addition, Poole (1992) recommended captive environments to be designed to provide the animal with “stability and security” and “opportunities to achieve goals”, in addition to complexity and unpredictability. Strategies for zoo animals are “constrained by factors such as space, available resources and visitor acceptability” as a result of important ethical obligations the public often have to animals (Mench and Kreger 1996) and these obligations often vary in weight depending of the purpose in which the animal is kept captive. Other constraints, including the effect of enrichment on animal health, are also common to the captive zoo environment.

 

The interest of exploratory behaviour and its relationship to information-gathering in animals, particularly in terms of is importance in improving welfare among captive animals has recently been renewed (Archer and Birke 1983; Poole 1992; Sheperdson et al. 1993; Wemelsfelder and Birke 1997). Which, consequently, increases emphasis on animals as the information gathered parallels those of the development of cognitive science.

 

Environmental devices however, sometimes appear to be selected more for their durability, safety, availability, cost or appeal than for any properties they might hold that are salient to the animal. Consequently, the enrichment devices will not be used by the animals and may not show the beneficial effects expected. Therefore, through viewing enrichment from the perspective of the information-gathering needs of the animal, will enable us to develop enrichment strategies more systematically and effectively.

• One way one can avoid continuing trial-and-error approach in enrichment programs, one must acquire more information about the attributes of the environmental features (e.g. visual characteristics, odours, sounds, and tactile characteristics) and enclosure (e.g type of three-dimensional space including height, angles, crevices, floor area, and number of levels) that both elicits and encourages exploratory behaviour. To some extent, this information may be obtained from observations of animals in the wild or naturalistic habitats.

• Several factors have been proved to influence exploration and responses to novelty in animals, including age, sex, genetics, and individual variation (Jones 1987; Renner and Rosenzweig 1987; Jones et al. 1991; Lawrence et al. 1991; Renner et al., 1992). 

• The animal’s history with either an enriched or impoverished environment during its development phase has great effect on neutral organisation and later patterns of emotional behaviour and responses to stressors (Molberg 1985; Renner and Rosenzweig 1987), and the varying results of the benefit enrichment has on behavioural changes (Newberry 1995), however, is controversial. The effects of early enrichment strategies must therefore be evaluated cautiously from the perspective of the natural history of neophilia and neophobia in a species, particularly for animals that might be reintroduced into their natural habitat (Sheperdson 1994).

• Environmental enrichment has been investigated`ted as a means for achieving practical goals and resolving short-term animal welfare problems. With one critical factor that influences the effectiveness of the enrichment being the degree of control the animals has with respect to seeking and interacting with, or conversely avoiding, novel stimulation in the enrichment. Therefore, giving the animal control thus appears to decrease the stress associated with novelty. Wemelsfelder and Birke (1997) emphasised the importance of the voluntary and interactive aspects of exploration and suggested that animals need to “do” as well as “learn”, and researchers Maier and Seligman (1976), in their wildly cited paper, has also argued that a state of learned helplessness occurs when an animals lacks control over environmental stimulation and thus has difficulty perceiving the relationship between its own behaviour and the results of its behaviour. Therefore, through allowing the animals to choose the intensity and duration of novel stimulation to which it is exposed to may help decrease paradoxical effects of enrichment.