Federal regulations developed to implement the Animal Welfare Act of 1985 require every research institution that uses nonhuman primates to develop and adhere to an Environmental Enhancement Plan that promotes the psychological well-being of the animals. Little scientific information exists to guide animal caretakers in the development of such standards. Lack of such information can result in arbitrary, subjective standards that are expensive to implement and yet have no significant impact on the welfare of the animals. This project is determining the effects on psychological well-being of three basic features of housing for laboratory primates which must, for research reasons, be housed in single cages most of the time. The effects of cage size, social contact and exercise space are studied. In addition, the effects of several common laboratory research procedures are under evaluation, including tethering, an alternative to chronic restraint of laboratory primates. Psychological well-being is assessed by a combination of hormonal , cardiovascular, and behavioral measures. Individual preferences are assessed by established behavioral methods. Unexpected findings to date are that, for one commonly used species, 1) cage size variation over a wide range has little impact on psychological well-being, and 2) the measures required to meet the social needs of adult males are quite different from those of adult females. The needs and preferences of wild-reared monkeys of a commonly used laboratory species (Macaca fascicularis) are compared with those of a related species (Macaca nemestrina) whose ecological niche and behavioral profile suggest that its responses to laboratory housing and procedures may be quite different. The results of these studies will enable primate colony managers and regulatory personnel scientifically to develop caging systems and housing policies that maximize the psychological well-being of the most commonly used laboratory primates.
