Effect of copper level and zinc level and source on finishing cattle performance and carcass traits

Abstract

Scope and Method of Study: The purpose was to evaluate the effects of Cu level and Zn level and source (organic vs. inorganic) on performance and carcass merit of cattle fed high-concentrate diets. In Study 1, the effects of two levels (DM basis) of Cu (12 vs. 24 mg/kg DM), two levels of Zn (80 vs. 360 mg/kg DM), and two sources of Zn (ZnSO4 vs. AvailaZn) on feedlot cattle performance and carcass merit were determined. In Study 2, the effects of feeding 60 mg of Zn from ZnSO4/kg of DM (control); control plus 30 mg of Zn from ZnSO4/kg DM; control plus 30 mg of Zn from ZINPRO100 Zn methionine/kg of DM; control plus 30 mg of Zn from AvailaZn/kg of DM; control plus 60 mg of Zn from ZnSO4/kg of DM; control plus 60 mg of Zn from AvailaZn/kg of DM, and control plus 60 mg of Zn from ZINPRO100 Zn methionine/kg of DM on feedlot cattle performance and carcass merit were determined.

Findings and Conclusions: Zinc and copper appear to alter carcass fat deposition independently of each other. While the present study suggests that supplementation of Zn at 360 vs. 80 mg Zn/kg DM increases deposition of external fat, there appeared to be no affect on intramuscular deposition due to Cu level, Zn level or Zn source in the present experiment. Performance seems to be enhanced by supplemental Zn in the initial portion of the feeding period; however, consistent results were not observed throughout the entire feeding period. Although results were inconsistent, Zn level and supplementation of organic Zn sources might enhance performance and carcass quality of finishing steers. While the relationship between Zn sources and levels is not clear, there appears to be an effect of Zn on carcass fatness at dietary concentrations between 80 and 280 mg of total Zn/kg of DM. The potential for improved carcass merit with increasing levels and organic sources of Zn warrants further research.