Digestible and Metabolizable Energy Requirements for Winter Maintenance of Michigan White-Tailed Does

Abstract

Eighteen pregnant white-tailed does (Odocoileus virginianus) were assigned to 6 trios on the basis of weight. They were penned individually out-of-doors from February S to April 9, 1969, and were fed a pelleted diet with a gross energy density of 4.20 keal/g and a crude protein percentage of 17.6. One member of each trio received the diet ad libitum; the second and third members received 75 and 50 percent of this amount, respectively. A subsequent l-week adjustment plus 1-week fecal and urine collection in metabolism cages was used to estimate the apparent digestible and metabolizable nutrient content of the diet. A linear regression of feed intake with average daily body weight gain or loss provided the basis for estimating maintenance energy requirements at mean weekly ambient temperatures ranging from 1.1 to -9.S C. The average estimated daily maintenance requirement for the 9-week period was 158 keal of apparently digestible energy and 131 keal of metabolizable energy per kg BW0 76. The following study was conducted to confirrn and extend our previous findings ( Ullrey et al. 1969 ) concerned with digestible energy needs for maintenance of body weight in captive adult white-tailed does during a Michigan winter. The development of an improved metabolism unit permitted the quantitative collection of both urine and feces and consequent calculation of metabolizable energy needs. The diet used was designed specifically for deer, and the formulation was based, in part, on deer research. We wish to acknowledge the assistance of Hazel Harte, Kay Cotton, Karen Jones, and Janice Mercer in performing laboratory analyses, and of E. H. Cunningham, F. L. Shippy, J. R. Terry, and R. E. Morrill for animal care. 1 Published with the approval of the Director of the Michigan Agricultural Experiment Station as Journal Article No. 5067. Supported by the Michigan Department of Natural Resources and PittmanRobertson Federal Aid in Wildlife Restoration Project Michigan W-95-R-ll. Research conducted at the Houghton Lake Wildlife Research Station. EXPERIMENTAL PROCEDURE Eighteen pregnant white-tailed does were assigned to 6 trios on the basis of weight so that the weights of the deer within a trio were as similar as possible. The heaviest individual deer within a trio was initially no more than 10 percent heavier than the lightest except for Trio 5 where there was a 19 percent difference. The mean body weights ( + SE ) for the deer in Trios 1 through 6, respectively, were 68.0 + 1.3, 64.0 + 1.7, 56.9 + 1.2, 57.3 + 1.2, 57.4 + 3.1, and49.7+1.3kg. All deer were 2.5 or 3.5 years old and had been raised in captivity from birth. They were penned individually out-ofdoors in an area 4.5 x 9 m. Protection from the weather was afforded by snow fence on two adjacent sides of the pen and a small roofed shelter. The other fences sere of