Use of Bioelectrical Impedance Analysis to Measure the Fat Mass of the Japanese Black Bear(Ursus thibetanus japonicus)

Abstract

Body fat mass(FM) of the Japanese black bear (Ursus thibetanus japonicus) was examined by bioelectrical impedance analysis(BIA) using Model Quantum X (RJL systems). Whole-body resistance was measured between forelimbs and hind limbs in the recumbent position. The FM was calculated by the equations for the American black bear. In 5 captive Japanese black bears, from September 2005 to January 2006, changes in FM and body mass(BM) were highly correlated (r=0.89). This study demonstrates that BIA is useful in the measurement of FM in the Japanese black bear, and that an increase in BM in autumn means an accumulation of FM. Seasonal changes in fat ratio(FR) in captive female Japanese black bears indicated lowest (29.3±3.3%) in early September and highest (41.6±3.0%) in December. The total fat accumulation (36.6kg FM) before hibernation corresponded to 252,000kcal and was consumed at 1,900kcal/day during hibernation. In 13 wild bears (in Gifu and Yamanashi Prefecture), FR was 6.9 to 31.7% from June to November 2006. The values in these wild Japanese black bears were low in comparison to those in captive bears. In conclusion, BIA facilitates the gathering of information on the live Japanese black bear's nutritional conditions and estimates their habitat environment through the year.