Starving and Refeeding Mule Deer

Thirteen fawn and 13 doe mule deer (Odocoileus hemionus) were starved 10 to 64 days and subsequently refed. Four fawns starved 33 and 34 days and one doe starved 54 days died. Fawns lost weight at twice the rate of does. Analyses of blood glucose, free fatty acids, and urea nitrogen from starving deer indicated that does and fawns catabolized stored fat to maintain blood energy metabolites. Fawns apparently depleted endogenous fat reserves sooner than does and began to catabolize muscle protein as an additional source of energy. Deer that after starvation were fed a diet with 14 percent protein and 9.7 percent fiber ate more than deer fed a diet with 3.8 percent protein and 41.3 percent fiber. Only one deer died during refeeding, and deer did not exhibit digestive upsets after the initiation of feeding on either diet. Blood parameters of deer returned to prestarvation levels 10 days after feeding. J. WILDL. MANAGE. 39(4):663-669 Loss of many deer to starvation occurs irregularly in areas with harsh winters (Chase and Severinghaus 1949, Cheatum 1956, Haynes 1967, Severinghaus 1973). Failure of emergency feeding to prevent large losses of starving deer has been a perplexing problem. Most attempts to feed starving deer have been initiated after deer had begun to die (Severinghaus 1963, Keiss and Smith 1966, Giles and McKinney 1968). Usually deer continue to die even after days or weeks of feeding (Carhart 1943, Doman and Rasmussen 1944, Hesselton 1964). Fawns comprise a disproportionately large segment of deer mortality on feeding grounds (Doman and Rasmussen 1944, Cheatum 1956, Dahlberg and Guettinger 1956:186, Hesselton 1964). These results have suggested that unacceptable winter losses of starving deer cannot be prevented by feeding (Carhart 1943, Doman and Rasmussen 1944, Cheatum 1956, Hesselton 1964, Haynes 1967, Giles and McKinney 1968, Kelsey 1973). Hypotheses have been generated to explain failure of feeding to prevent further losses of deer. Lee (1957), Nagy et al. (1967), Giles and McKinney (1968), and Pearson (1969) suggested that all or some species of rumen microorganisms died during starvation, rendering deer unable to digest feeds upon refeeding. deCalesta et al. (1974), however, demonstrated that deer maintain abundant viable, functioning rumen bacteria after 7-47 days of starvation. Giles and McKinney (1968) theorized that toxic fermentation and/or metabolic products resulting from emergency feeding might cause mortality of starved deer. Overeating by refed deer, which may lead to abnormal and toxic rumen fermentation products (Church 1969:293), has been suggested as a mortality agent (Fowle and Church 1969). Others (Lee 1957, Haynes 1967) suggested that there is a time in starvation when deer are near to death and beyond which refeeding fails to save them. Starving mammals catabolize body tissues to sustain levels of energy metabolites (glucose and ketone bodies). Glucose is derived from muscle protein and fat deposits via gluconeogenesis. Ketone bodies, chiefly aceto-acetate and p hydroxybutyrate, are derived from oxidation of body fat (Young and Scrimshaw 1971). The degree to which 'Present address: Department of Fishery and Wildlife Biology, Oregon State University, Corvallis 97331. J. Wildl. Manage. 39 (4):1975 663 This content downloaded from 207.46.13.129 on Fri, 01 Jul 2016 04:57:37 UTC All use subject to http://about.jstor.org/terms 664 STARVING AND REFEEDING DEER ? deCalesta et al. these and other processes occur in starving deer is unknown. In this study we verified that fawns are less able to withstand lengthy periods of starvation than are adult deer. Additionally, we documented and compared changes in metabolism of does and fawns occurring during starvation and refeeding. We thank R. W. Phillips, Department of Physiology and Biophysics, Colorado State University, for his advice and use of his laboratory for blood analyses. Assistance of S. Kerr, W. Paintner, R. Pofahl, D. Reeder, C. Schwartz, and G. Schoonveld in handling deer was greatly appreciated. Financial aid and pen space were provided by the Colorado Division of Wildlife (P-R Project W-38-R-24) in cooperation with the U. S. Fish and Wildlife Service.