Effect of dietary copper and zinc concentrations on white-tailed deer antler growth, body size, and immune system function

Copper (Cu) and zinc (Zn) influence growth and immune function of animals. To determine the effect of high concentrations of these minerals on body size, antler growth, and immune function of white-tailed deer (Odocoileus virginianus), we fed captive male deer either a control diet with 24–40 ppm Cu (as copper sulfate) and 117–200 ppm Zn (as zinc oxide) or a treatment diet with 200–236 ppm Cu and 1000–1135 ppm Zn. Diets were fed to mature (>4 years old) male deer over an 18 month period and to 1–2 year old male deer over a 1 year period between March 1999 and October 2000. In nutrient balance trials, mature deer consuming the treatment diet had a higher nitrogen balance and equal Cu and Zn balance compared to the control diet. Deer on the treatment diet showed evidence of periodically purging Cu and Zn from their system. There was no effect of diet on antler or body size. Mature deer on the treatment diet had a greater immune response to an antigen challenge and less immune inhibition from stress hormones. Young deer on the treatment diet also showed a greater immune response to an antigen challenge, but the effect was less than in the mature deer. No indication of Cu or Zn toxicity was observed. We conclude that feeding high concentrations of Cu and Zn to male white-tailed deer will not increase antler or body size in deer >1 year of age, but that immune function may benefit.