Energy Requirements of Adult Moose for Winter Maintenance

Abstract

Nine adult moose (Alces alces) were randomly assigned to 1 of 3 diets in 2 separate feeding trials. Our objectives were to determine how moose respond in winter to varying amounts of the same quality of food, and to the same amount of food which possessed varying nutritional quality. During trial 1, moose were fed a pelleted diet ad libitum, and 85.1 and 72.5% of the ad libitum diet. During trial 2, moose were fed ad libitum 1 of 3 pelleted diets containing digestible energy concentrations of 2.4, 2.1, and 1.8 kcal/g dry matter. Linear regression equations of digestible energy intake (kcal/kg body wt [BW].75/day) with mean monthly body weight gain or loss (kg/day) provided the basis for estimating maintenance energy requirements. Our best estimates of energy required for maintenance were 148 and 131 kcal/kg BWo075/day of digestible and metabolizable energy, respectively. The relationship between heat production and metabolizable energy intake provided an estimate for theoretical basal metabolism of 73 kcal/kg BW0-75/day. J. WILDL. MANAGE. 52(1):26-33 Wild moose weight loss during winter (Franzmann et al. 1978) is assumed to be caused by declines in forage quality and abundance. However, captive moose fed a diet of constant quality all year lost weight during winter regardless of food availability (Schwartz et al. 1984). Under natural conditions, moose lose weight in response to declines in forage quality and availability during winter. However, weight loss is also affected by certain physiological mechanisms that affect metabolic rate. Metabolic rate can vary seasonally (Regelin et al. 1985) with changes in food consumption (Hubbert 1987) and fat catabolism (Abbott et al. 1984). Shifts in metabolic processes may ultimately determine survival. Because the mechanisms controlling weight loss in moose are not simply driven by food quality and availability, our objective was to determine how moose respond in winter to varying amounts of the same quality of food, and to the same amount of food with varying nutritional quality. By determining these responses we were able to calculate maintenance energy requirements during winter and document changes in weight associated with various levels of energy consumption. We appreciate the help of D. C. Johnson, J. S. Bevins, R. W. Bale, C. Lodge, D. M. Waring, C. A. Bando, and D. J. Groves with animal care and sample collection. E. F. Becker and D. J. Reed helped with statistical analysis, and K. B. Schneider, L. A. Renecker, S. R. Peterson, M. Branine, and B. Townsend reviewed the manuscript. This study is a contribution of Federal Aid in Wildlife Restoration, Project W-17 and W-21.