Meeting Abstract
P3.124 Jan. 6 Dual energy X-ray absorptiometry (DXA) can accurately and non-destructively measure the body condition of small, free-living rodents STEVENSON, K.T.*; VAN TETS, I.G.; University of Alaska Fairbanks/ University of Alaska Anchorage; University of Alaska Anchorage ftkts2@uaf.edu
The whole body condition of free-living mammals has previously been measured using methods that are either lethal to the study animal, destructive to tissues, contain high amounts of internal variation, or that have been deemed inaccurate, inconsistent, or too general. Dual energy X-ray absorptiometry (DXA) is a non-destructive technique that can potentially measure specific body condition components in free-living and lab-raised animals with good precision and accuracy. Our aim was to test the ability of DXA to determine the body condition of northern redbacked voles (Clethrionomys rutilus). We scanned free-living and lab-raised voles using DXA to obtain measurements of fat mass, lean mass, bone mineral content, bone mineral density, and fat-free mass. We then used proximate analysis to measure actual fat mass, total body water, total protein, total mineral, total lean mass, and fat-free-mass. We used the relationships between the data obtained by the two methods to derive algorithms that require only DXA measurements to accurately predict several parameters of condition (body mass, fat mass, total body water, total protein, total mineral, total lean mass, and fat-free mass). Body fat was predicted by DXA with sufficient accuracy for free-living and lab-raised voles (y = 0.89x � 0.42; R2 = 0.84), but was best predicted by subtracting fat-free mass from gravimetric body mass, as DXA predicted fat-free mass in voles with excellent precision and accuracy (y = 0.97x + 0.14; R2 = 0.98). We found that standard rodent PIT tags significantly (p<0.05) altered all four DXA parameters, and we calculated corrective terms that allow for measurements of body condition in tagged, sedated animals. Thus, DXA is a non-lethal, non-destructive tool that is capable of measuring many specific parameters of body condition in small, free-living and lab-raised rodents with excellent precision and accuracy.
