Femurs, mandibles, and kidneys with attached perirenal fat were collected from white-tailed deer (Odocoileus virginianus) in controlled and field studies to examine the use of fat indices for assessing nutritional status. Eleven fawns were fed formulated rations differing in energy content for 4 weeks. The kidney fat index (KFI) was significantly lower for fawns fed low energy (LE) diets compared to high energy (HE) diets. Femur marrow (FMF) and mandibular marrow fat (MMF) levels were unaffected by diet. In another experiment, 9 fawns were fed diets differing in energy and protein content for 13 weeks. In this experiment, all fat indices were lower in fawns on LE diets than on HE diets. Protein intake had no effect on the fat indices. Samples also were collected from 98 captive and wild deer to examine correlations among the fat indices. A significant correlation (r = 0.44) was observed between FMF and MMF. Significant correlations of FMF with KFI (r = 0.78) and MMF with KFI (r = 0.53) when plotted revealed an inverse quadratic relationship. Thus, kidney fat reserves appeared to be used at an early stage of malnutrition and were almost depleted before FMF and MMF reserves were mobilized.
