Comparison of Short-Term Health and Performance Effects Related to Prophylactic Administration of Tulathromycin versus Tilmicosin in Long-Hauled, Highly Stressed Beef Stocker Calves

Bovine respiratory disease (BRD) is the most common disease condition in both the stocker and feedlot stages of beef production. This syndrome causes economic loss in the form of treatment costs, loss of growth performance, decreased quality grade, and higher mortality risk. Metaphylactic antimicrobial therapy upon arrival to a feedlot facility has been intensely studied and repeatedly shown to be a cost-effective practice in  many production settings. Two approved metaphylactic drugs, tilmicosin and tulathromycin, are members of the macrolide class of antibiotics. The stocker segment of the beef industry is traditionally a grower phase for young, lightweight calves prior to their entry into a feedlot. However, stocker calves are on feed for a much shorter duration than calves in the finishing period in feedlots. Therefore, maintaining a high level of health and growth performance is imperative. The objective of this research was to determine if health and performance differences were present when comparing a longer-acting (tulathromycin) or shorter-acting (tilmicosin) antimicrobial administered to beef stocker calves at arrival.