A comparison of dual-energy X-ray absorptiometry and somatometrics for determining body fat in rhesus macaques

Objective: Various approaches have been used to assess fat and fat distribu tion in nonhuman primates, including measurements of body weight, body dime nsions, and estimates derived from these, such as body mass index. Methods such as tritiated water dilution and dual-energy X-ray absorptiometry (DXA) have also been used. The aim of the present study was to evaluate and comp are DXA measurements and somatometrics, Research Methods and Procedures: Body composition of 15 adult male rhesus m acaques was measured by DXA and somatometrics at four time-points over a 4- year period. Additionally, DXA precision and somatometric variability were analyzed by repeated measurements of the same subjects. Results: DXA estimates of body fat were positively correlated with body wei ght, body mass index, body circumferences, and abdominal skinfold thickness es. DXA assessments of soft tissue composition were precise, with coefficie nts of variation below 3.3% for all compartments analyzed. The majority of the observed variability in somatometrics was explained by subject variance , rather than by inter- or intraobserver variability, or by observer experi ence level. Discussion: We conclude that noninvasive DXA technology provides precise es timates of nonhuman primate body composition that correlate well with the t raditional somatometric measures used in primate studies.