Body composition changes in white-tailed deer fawns during winter

Abstract

Sixteen white-tailed deer (Odocoileus virginianus) fawns were captured near Chicago, Illinois, between November and April, and their body composition was determined, to investigate changes in body composition and chemical component distribution as they catabolized tissues over the winter. Live weights of the fawns ranged from 16.8 to 41.6 kg (31.1 ± 2.0), and ether-extractable fat concentration of the bled, ingesta-free body ranged from 2.3 to 48.9% (24.5 ± 4.7) on a dry basis. Carcass, viscera, and hide contained, on average, 70, 21, and 9% of the bled, whole body fat, respectively. Above approximately 15% whole body fat (dry basis), the percentages of whole body fat contributed by the viscera and carcass increased and decreased, respectively. Body composition (blood-, ingesta-, and fat-free basis) averaged 72% water, 23% crude protein, and 5% ash; ash and phosphorus concentrations increased and protein concentration decreased over the winter. Sodium concentration tended to decrease. Based on relationships between chemical components and body weight, the composition of weight lost during winter was calculated to range from 12% water, 84% fat, 4% protein, and 0.5% ash during early winter to 73% water, 0.3% fat, 25% protein, and 2% ash during early spring. Calculated metabolizable energy derived from tissue catabolism was a quadratic function of body weight and ranged from 7.7 to 1.1 Mcal/kg of bled, ingesta-free weight loss during early and late periods.