Abstract This administrative supplement seeks funds to purchase a newly developed dual energy X-ray absorptiometry (DEXA) system that will enable UTHSCSA’s Nathan Shock Center (NSC) to offer state-of-the-art technology for in vivo and ex vivo assessment of body composition and bone mineral density of aging animals. Currently, our NSC Aging Animal Models and Longevity Assessment Core is responsible for breeding and maintaining several thousand aging mice, a naked mole rat colony, and aging common marmosets for investigators in San Antonio and nationwide. This Core in conjunction with the Integrated Physiology of Aging Core provides investigators with healthspan measures ranging from lipidomics, single cell transcriptomics, muscle function, frailty, cognition and behavior to pathophysiology. The DEXA system will fill a critical gap in these age-related phenotyping services missing since an earlier outdated, highly used system had to be abandoned over a decade ago, due to the manufacturer stopping production and no longer providing repair service. The addition of in vivo DEXA assessment of body composition (lean and fat mass) and bone mineral density and content will thus provide critical outcome measures that will benefit many investigators using NSC Core services to study topics such as the effects of diet and nutrition, food restriction, and drug and genetic interventions on aging processes. The NSC at San Antonio has been part of the Barshop Institute for the Study of Aging for over 27 years, providing specialized services and consultation for aging research to many investigators seeking to understand and develop therapeutic interventions to ameliorate the aging process. During this time, the NSC Cores have undergone a continuous expansion to provide ever more comprehensive phenotyping of aging-sensitive traits. Far superior to the earlier system, the newly developed DEXA system is a fully shielded system with a much higher resolution (100 µm µm pixel size @ 1.2x and 31 µm @ 4x, along with a wide scan area, allowing for animals weighing from 0-500 grams (mice to marmosets). Furthermore, it can either scan the selected region of interest or ex vivo samples (e.g., excised bones, organs), at a higher resolution. It is well suited for longitudinal aging studies as the radiation dose is minimal, (0.66mGy per scan). Therefore, the accumulation of multiple imaging timepoints will have minimal effects on animals during each imaging session, and are unlikely to affect study outcomes. Scans only take 25 seconds to complete, allowing for high throughput of animals. It will be installed in one of the rooms dedicated to measuring healthspan traits in the Aging Animal Core Facility in the Barshop Institute. This request for a DEXA system conforms to the stated purpose of supporting and enhancing shared resources for categorical research by many investigators from different disciplines. The DEXA system will be an added benefit that will provide more comprehens...