No abstract

Previously, we observed a strong correlation between immunity parameters of neonatal white-tailed deer (Odocoileus virginianus) fawns and probability of survival in an overpopulated herd. As a result, we monitored age-related changes in neonatal fawn physiology, with an emphasis on measures of passive immune transfer, to test the hypothesis that maternal protein malnutrition adversely influences the vigor and immunocompetence of newborn fawns. Body mass and physiological data were collected from 55 neonatal fawns (1–28 days old) born to captive does on either a high-protein (16%) or low-protein (6.5%) diet during the latter half of gestation through lactation (15 March – 1 September). The study was conducted over two breeding seasons (1992 and 1993), with does receiving the same diet the second year to assess diet × year interactions. We found little evidence of compromised immunocompetence of neonatal fawns born to protein-malnourished does in either year. The absence of any sign of suppressed in utero development suggested that the nutritional deficiencies of the diet regime we used may not have been chronic enough to mirror conditions that exist in the wild. Birth mass, hematology, and serum chemistries of fawns suggested that low-protein diets caused reductions in maternal nutritional status by the second year. The results of this study and those of preliminary field observations suggested that compromised immunocompetence of neonatal fawns may be manifested only during chronic malnutrition, when the protein reserves of does become depleted or insufficient.

White-tailed deer (Odocoileus virginianus) derive the majority of their dietary mineral intake from range forages which may be deficient in one or more essential minerals. We have described the macro and trace mineral concentration of 18 shrub, 26 forb, 7 grass, and 1 cactus species, known to occur in south Texas deer diets, collected from the Chaparral Wildlife Management Area in 1974 and 1975. Within each forage class, there were no seasonal differences in calcium (Ca), sodium (Na), potassium (K), or magnesium (Mg) concentrations. Phosphorus (P) concentrations in browse were higher (PI0 051 durinn the snrinn (0.20%) thnn dur-_~ _~~~~ _ __e__, ______ _ _..-=_____ \_ .__, ",-__-ing other seasons(O.U-0.16%). Forb P concentrations were greatest during the spring and winter periods (0.26 and 0.2970, respectively), and P levels in grasses (0.24-0.14%) decreased as the forage matured and reached senescence. Shrubs contained less P and K (p10.01) than either grasses or forbs; whereas, grasses contained lower concentrations of Ca and Mg (EO.01) than shrubs or forbs. Sodium concentrations did not diier among forage classes. Forbs contained greater (fiO.01) levels of copper (Cu) and zinc (Zn) than erasses or browse-nnd hr~wm c~n!ri~ed 1~9s ire" (Fe! m-I-(%0.01) than forbs or grasses. Manganese concentrations did not differ among forage classes. There were differences in mineral concentrations among species within forage class. Results suggest concentrations of all minerals except P met or exceeded minimum domestic animal requirements. Managers should provide a diversity of plant species and encourage practices that promote forb growth to provide optimum and nutritional benefits for deer.

No abstract

A study was conducted from May 1986 to June 1987 with white-tailed deer (Odocoileus virginianus) to determine seasonal nutritive value and nutrient digestibilities of guajillo (Acuciu berlandieri) and a pelleted diet. In vivo dry matter digestibility (DMD) of guajillo varied seasonally from 35.2 to 48.1% and was inversely correlated to levels of condensed tannins in the forage. Apparent protein digestibility varied seasonally from 13.7 to 45.8% and was a highly dependent function (R* = 0.97) of the amount of neutral detergent fiber nitrogen (NDFN) digested and the negative impact of condensed tannins. Cellulose and hemicellulose digestibilities also varied seasonally (0.6 to 13.5% and 52.3 to 71.1%, respectively). Nutrient digestibilities of the pelleted diet did not vary by season, sex, or age. Dry matter digestibility of the pelleted diet was 75.6$$0 f 0.9 and true protein digestibility was 95.0 f 0.04. Results suggest summer is a stressful period for south Texas deer due to low protein and energy digestibility and high levels of condensed tannins.Varner and Blankenship 1987, Barnes et al. 1990). Answers to these questions would allow a more adequate determination of rangeland nutritional carrying capacity for white-tailed deer. Because many ranchers in south Texas feed deer a supplement year round, we also investigated in vivo nutrient digestibilities of a pelleted ration, thus determining the optimum period for supplementation. MethodsThe dietary importance of forage species studied was determined from published studies (Hughes 1982, Varner and Blankenship 1987) and examination of rumen contents of sacrificed deer from Dimmit, LaSalle, Maverick, Uvalde, and Zavala counties, Texas (Varner unpubl. data). Guajillo (Acacia berlandieri) is eaten by deer and cattle during all seasons and may constitute up to 37% of the diet (Hughes 1982, Varner and Blankenship 1987). . Serve110 provided helpful comments on earlier drafts of this manuscript. This is contribution TA239900 of the Texas Agricultural Experiment Station. the pelleted diet was not conducted during the fall because this is not a nutritionally stressful period for deer. Experimental animals were born in captivity, hand-reared on evaporated milk and calf starter, and thereafter maintained on a nutritionally complete pelleted ration supplemented with browse, alfalfa, or native hay, and field corn. A mixture of adult (>2.5 years of age) male and female animals, that were well acclimated to metabolism crates, were used in trials with guajillo because there were no differences in pelleted diet nutrient digestibilities attributed to sex.Deer (N = 6) were confined in 1.2 X 1.2 X 1.2 m metabolism crates that were housed in a climate-controlled room. Temperatures closely approximated outdoor conditions except in summer,