Zilpaterol hydrochloride, or Zilmax, is a beta-agonist approved to be fed to finishing cattle the last 21 days of the feeding period. There is a three-day withdrawal for this feed additive, so careful management is necessary for responsible use of this technology. Recently, some animal welfare concerns were associated with the feeding of Zilmax, so researchers wanted to determine if feeding Zilmax to finishing cattle impacted performance, carcass characteristics, mobility, body temperature, and response to heat stress when fed in the open or in shaded pens.