The lower row monkey cage: an overlooked variable in biomedical research.
Reinhardt, V. and Reinhardt, A.
Journal of Applied Animal Welfare Science, 3(2), 141-149 (2000).
A survey of 96 primatological articles revealed that cage location of research monkeys is rarely mentioned, although the environment of upper and lower row-housed animals markedly differs in terms of light quality, light intensity, and living dimensions. Not accounting for these uncontrolled variables may increase variability of data and, consequently, the number of experimental anomals needed to obtain statistically acceptable results. This study concluded that single-tier housing would be an important refinement of research methodology. Such housing would (a) enable all animals of a room to use the "aboreal" dimension of their enclosure and retreat to "safe" vantage points above the human "predator," (b) offer all animals access to uniform light, and (c) provide more favourable conditions for professional animal care.