IntroductionFrom May 13 to August 7, 2014, I was in Dakota City, Nebraska, as a Tyson Fresh Meats carcass merchandising intern. Most of my time in the Dakota City facility was spent working through the quality chain applying USDA grading requirements and Tyson Merchandising labeling procedures. During my internship, I learned to examine cattle based on carcass characteristics. One of the things that really stuck with me and became an ongoing interest of mine was the use of β-adrenergic agonists. The carcasses we saw were physically different from naturally raised cattle as well as a significant difference in USDA quality. By natural breeding, I mean cattle that do not receive β-adrenergic agonist feed additives. The carcasses that appeared to have received these β-adrenergic agonists appeared extremely muscular. I was very interested in these β-adrenergic agonists that were fed and their relationship with the qualities of the carcasses that I saw on the rail. DiscussionThere is a large amount of information on β-adrenergic agonists, especially after their plant ban which began after my internship in September 2013. β-Adrenergic agonists have been studied for many years due to their advances in terms of growth potential. Commonly used β-adrenergic agonists in the United States and the β-adrenergic agonists we saw at Tyson were zilpaterol hydrochloride and ractopamine hydrochloride, otherwise marketed by Merck Animal Health as Zilmax (zilpatherol hydrochloride) and Opaflexx (ractopamine hydrochloride) from Elanco Animal Health. ). In 2003 and 2006, respectably, research-based feed additives were accepted for use to improve gain efficiency and became permitted in beef cattle...... middle of paper ..... ..HAS. Scanga, DR McKenna, WH Kolath, PL Chapman, JD Tatum, and KE Belk. “Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on longissimus muscle shear force and sensory attributes of beef cattle.” Journal of Animal Sciences. 91 (2013): 5989-997. Print.2. Delmore, RJ, Hodgen, JM and Johnson, BJ “Perspectives on the Application of Zilpatherol Hydrochloride in the United States Beef Industry” Journal Of Animal Science 88 (2010): 2825-2828. Print.3. RJ Rathmann, BC Bernhard, RS Swingle, TE Lawrence, WT Nichols, DA Yates, JP Hutcheson, MN Streeter, JC Brooks, MF Miller and BJ Johnson. “Effects of zilpaterol hydrochloride and days applied to the finishing diet on feedlot performance, carcass characteristics and tenderness of beef heifers.” » Journal of Animal Sciences. 90 (2013): 3301-3311. Print.