Macro and trace mineral content of selected south Texas deer forages

Abstract

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 (P less than or equal to 0.05) during the season (0.20%) than during other seasons (0.14-0.16%). Forb P concentrations were greatest during the spring and winter periods (0.26 and 0.29%, respectively), and P levels in grasses (0.24-0.14%) decreased as the forage matured and reached senescence. Shrubs contained less P and K (P less than or equal to 0.01) than either grasses or forbs; whereas, grasses contained lower concentrations of Ca and Mg (P less than or equal to 0.01) than shrubs or forbs. Sodium concentrations did not differ among forage classes. Forbs contained greater (P less than or equal to 0.01) levels of copper (Cu) and zinc (Zn) than grasses or browse, and browse contained less iron (Fe) (P less than or equal to 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.