RELATIONSHIPS BETWEEN BLOOD-SERUM VARIABLES AND DEPTH OF RUMP FAT IN ALASKAN MOOSE

Abstract

We studied the relationship between maximum depth of rump fat determined from ultrasound measurements an 22 blood values for Alaskan moose (Alces alces gigas) by sampling 38 pregnant, adult females. Moose were immobilized, and blood was drawn simultaneously with the determination of depth of fat rump during 1-4 March 1996. Multiple-regression models were used to detect relationships between blood-serum variables and depth of fat. Four of 22 blood-serum variables were removed to control for multicollinearity. Remaining variables were regressed against induction time (X̄ = 6.1 min, SD = 4.4 min). Glucose, sodium, and blood urea nitrogen were correlated with induction time (R²_a = 0.27, P = 0.010) and likely represented a response to handling; these blood values also were removed from the final regression model. Mallow’s Cp statistic indicated the most appropriate regression model included only 2 variables. Creatinine (X̄ = 2.08 mg/dl, SD = 0.26 mg/dl) and aspartate aminotransferase (AST) (X̄ = 79.10 U/l, SD = 13.61 U/l) met all necessary assumptions and explained a portion of the variability observed in fat depth. (X̄ = 1.5 cm, SD = 1.0 cm). Thus, our final model was: maximum depth of rump fat = 0.28 + 1.68(creatinine) - 0.03(AST). This model was significant (P = 0.0002) and accounted for 33.7% (R²) of  variability observed in fat depth. Partial regression coefficients for creatinine and AST were 0.222 (P = 0.0025) and 0.0150 (P = 0.006), respectively, and indicated that creatinine was slightly more influential than AST in the model. These blood variables may provide insights into the predicted condition of moose and the response of moose to environmental conditions. A model using blood variables thought to be indicators of physical condition (protein, phosphorus, and calcium) did not explain significant variation in maximum depth of rump fat.