Twelve white-tailed deer (Odocoileus virginianus) fawns were studied from October 1978 to October 1980 to determine mean daily feed intake'and seasonal digestive efficiency. Five adult bucks were added to the intake study as they became available. Mean daily feed intake/wtkg-75 declined through the 1st year for fawns with a sharper rate of decline evident during winter. Intake peaked in yearling deer in December and was markedly reduced during late winter, remaining at lowered levels until May. There was an upward trend, somewhat modified by summer heat, until the termination of the experiment in October. There was no difference (P > 0.05) in consumption/unit body weight between sexes and no seasonal difference (P > 0.05) in the digestibility of the feed. Bucks digested only protein better than does. Fiber digestion improved (P < 0.05) in both sexes with age. These data indicate a single period of intake suppression encompassing both the rut and winter in southern deer and no compensatory change in digestive efficiency. J. WILDL. MANAGE. 47(2):442-450 Deer in northern climates experience a predictable seasonal variation in feed intake. Studies of white-tailed deer by French et al. (1955, 1956), McEwen et al. (1957), Cowan and Long (1962), and Long et al. (1965) showed that males voluntarily decrease their intake during the rut and in midwinter while females and immature males exhibit moderate declines. Browse use (Ozoga and Verme 1970) and physical activities (Moen 1978) also decrease in white-tailed deer during the winter in northern areas. Periodicity of feeding activity has also been reported in other cervids in northern climates: mule deer (Odocoileus hemionus) (Wood et al. 1962), elk (Cervus elaphus nelsoni) (Robbins et al. 1981), caribou (Rangifer tarandus) (McEwen and Whitehead 1970), and roe deer (Capreolus capreolus) (Drozdz 1979). The cause of winter intake decline has been attributed to an inherited adaptation to winter food shortages (French et al. 1956), decreased metabolic requirements (Silver et al. 1969, Thompson et al. 1973, Holter et al. 1977, Moen 1978), endocrine changes (Mazur 1974, Ozoga and Verme 1978, McMillin et al. 1980), and photoperiod (McMillin et al. 1980, Bahnak et al. 1981). It is less clear how the temperate climate of southern states influences deer nutritional status. Studies of white-tailed deer in Louisiana by Fowler et al. (1967) and Short et al. (1969) showed a winter reduction in feed intake and body weights of yearling and adult deer and an additional decline in intake in summer. The latter decrease was attributed to high summer temperatures and humidities. Equally as important as intake is the quality and digestibility of the deer's diet. The seasonal variation in the quality (nutrient content) of deer diets and its effect on digestibility has been thoroughly demonstrated (Kirkpatrick et al. 1969; Short 1971, 1975; Smith et al. 1975; Blair et al. 1977; Holter et al. 1979). In domestic animals, high ambient temperatures are generally associated with low feed intake, whereas low temperatures are reflected in increased intake (Conrad 1966). Concur'Present address: Texas Parks and Wildlife Department, 1904 Sixth Ave., Canyon, TX 79015. 442 J. Wildl. Manage. 47(2):1983 This content downloaded from 207.46.13.122 on Fri, 01 Apr 2016 04:24:52 UTC All use subject to http://about.jstor.org/terms INTAKE AND EFFICIENCY OF SOUTH TEXAS DEER * Wheaton and Brown 443 rently, digestibility generally varies inversely with intake due to associated changes in the rate of passage (Church et al. 1971). Holter et al. (1977) found that the overall digestibility of deer feeds declined in midsummer in New Hampshire whitetails due to an increase in feed intake. Little work has been done on seasonal digestibility in deer. Baker et al. (1979) found that the digestibility of an experimental ration did not vary with the stresses of winter in mule deer fawns. Cederlund and Nystrom (1981) found no seasonal variation in the ability of moose (Alces alces) to digest browse, whereas roe deer on the same range demonstrated an increased ability to digest fiber during the winter. The objectives of this study were to determine the seasonal pattern of feed intake, body weight changes, and digestive efficiency in south Texas white-tailed deer and to examine the effect of sex and ageclass on these parameters. We thank R. Bingham for help with statistical analysis of the data. This project was funded by the Caesar Kleberg Foundation for Wildlife Conservation.
Read full abstract
Apr 1, 1997
J Koskela + 2
Open Access