Technical note: Feeding zilpaterol hydrochloride to calf-fed Holstein steers improves muscle conformation of top loin steaks

The objective of this research was to evaluate changes in the muscle conformation of subprimal top-loins (M. longissimus lumborum) from calf-fed Holstein steers fed zilpaterol hydrochloride (ZH). Top-loins (n =100) were transversely cut into 2.54 cm-thick steaks, weighed, and objectively evaluated via image analysis software for muscle area, width, and length traits. Top-loin steaks from steers fed ZH were heavier (P<0.01; 367 vs. 337 g) and average muscle area per steak was greater (P<0.05; 80.9 vs. 77.2 cm(2)) as compared to steaks from control steers. Muscle width (medial-lateral) was not different (P= 0.23) between control steers and those fed ZH. However, steaks from steers fed ZH had greater (P<0.05) depth (dorsal-ventral) than steaks from control steers throughout the top-loin. The increased muscle depth of top-loins from calf-fed Holstein steers fed ZH may improve the center-of-the-plate salability of a cut that has traditionally suffered from poor muscling. (C) 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.