Is a medicated feed premix used in the final finishing stage (30 days prior to slaughter) of feedlot cattle to improve the efficiency of feed conversion, weight gain, carcass yield and to reduce carcass fat in cattle. Contains 48% Zilpaterol hydrochloride. Contains 48% Zilpaterol hydrochloride. Grofactor is nearly 100% bioavailable following oral ingestion and almost completely eliminated within 72 hours - 3 day withdrawal. Stavigro technology ensures ensures the stability and uniformity of ZH in Grofactor and ensures homogenous mixing into feed.