Predicting body fat and body mass in moose with ultrasonography

Lipids are the primary energy store of the body and estimation of these reserves provides an indication of nutritional status in moose (Alces alces). Estimates of total body fat enhance our understanding of reproductive potential, survival rate, energy balance, and nutritional carrying capacity. We developed predictive equations of total body fat and body mass from ultrasonographic fat measurements for application in live animals. We detected a strong linear relationship (r 2 = 0.96) between ingesta-free body fat and rump fat thickness measured by ultrasonography. Rump fat thickness was measurable over a range of body fat levels (5.8-19.1%). Rump fat mass (r 2 = 0.92) and kidney fat mass (r 2 = 0.95) were curvilinearly related to ingesta-free body fat level. For adult females, total length and chest girth were not related to body mass. Ingesta-free body fat, however, explained 81% of the variability in body mass, and ultrasonically measured rump fat thickness predicted body mass (r 2 = 0.80).