Effects of supplemental zinc, copper, and manganese concentration and source on performance and carcass characteristics of feedlot steers 1 1Use of trade names in this publication does not imply endorsement by Colorado State University or criticism of similar products not mentioned. Mention of a proprietary product does not constitute a guarantee or warranty of the products by Colorado State University or the authors and does not imply its approval to the exclusion of other products that may also be suitable.