West, A. M., Leland, S. P., Muhammad, F. et al. 2010. Temperament ratings of laboratory rhesus macaques (Macaca mulatta): Effects of cage level and room composition. American Journal of Primatology 72(S1), 42. (33rd Meeting of the American Society of Primatologists Scientific Program, Abstract #52)

Measures of temperament in nonhuman primates generally reflect interactions between inherent individual characteristics and environmental contexts, and they may be indicators of physical and psychological well-being. Heritable aspects of temperament have been identified, but it is useful to evaluate the extent to which temperament ratings are influenced by components of laboratory environments. Tiered caging systems have been criticized as harmful to primates housed on the lower tier, so we examined possible effects of cage level on temperament ratings of rhesus macaques. We tested the null hypothesis that macaques in upper and lower cages in an AAALAC-accredited biomedical research facility would not differ with regard to temperament ratings. We also evaluated possible influences of origin (Chinese or Indian), room composition (same sex versus mixed sex), and lighting conditions (lower tier cages with or without supplementary lighting). During systematic behavioral observations, animals were assigned temperament ratings (A=aggressive, B1=intermediate aggressive, B2=intermediate submissive, C=submissive) based on behavior directed toward conspecifics or observers. No significant effect of cage level on temperament rating was detected [Difference Between Two Proportions; z=2.131; P>0.05]. Interestingly, there was an effect of origin, with a significantly higher proportion of Chinese than Indian rhesus receiving submissive (C) ratings [P<0.05], regardless of cage tier. No other significant effects of room composition or lighting conditions on any of the temperament ratings were found.