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This Article Free Via Open Access Full Text Full Text (PDF) All Versions of this Article: jas.2009-1830v1 87/11/3722    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Boler, D. D. Articles by Allen, D. M. PubMed PubMed Citation Articles by Boler, D. D. Articles by Allen, D. M.

Effects of feeding zilpaterol hydrochloride for twenty to forty days on carcass cutability and subprimal yield of calf-fed Holstein steers

D. D. Boler^*, S. F. Holmer^*, F. K. McKeith^*, J. Killefer^*,1, D. L. VanOverbeke, G. G. Hilton, R. J. Delmore, J. L. Beckett, J. C. Brooks^#, R. K. Miller^||, D. B. Griffin^||, J. W. Savell^||, T. E. Lawrence^¶, N. A. Elam^**, M. N. Streeter, W. T. Nichols, J. P. Hutcheson, D. A. Yates and D. M. Allen

^* Department of Animal Sciences, University of Illinois, Urbana 61801; and Department of Animal Science, Oklahoma State University, Stillwater 74078; and Department of Animal Science, California Polytechnic State University, San Luis Obispo 93407; and Beckett Consulting Services, Atascadero, CA 93422; and ^# Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409; and ^|| Department of Animal Science, Texas A&M University, College Station 77843; and ^¶ Department of Agricultural Sciences, West Texas A&M University, Canyon 79016; and ^** Clayton Livestock Research Center, New Mexico State University, Clayton 88415; and Intervet Schering Plough, Desoto, KS 66018

¹ Corresponding author: jkillef{at}illinois.edu

Zilpaterol hydrochloride (ZH) is designed to increase carcass leanness, chilled side weight (CSW), and percent saleable yield. The objective of this study was to evaluate the effect of a single dose of ZH on cutability and subprimal yield of calf-fed Holstein steers when fed for increasing durations. Two hundred forty steers were fed 8.3 mg/kg of ZH on a DM basis for 0, 20, 30, or 40 d, with a 3-d withdrawal before slaughter. After slaughter, steers were fabricated into 4 pieces (round, loin/flank, rib/plate, and chuck), packaged in combos, shipped to 2 locations, and further fabricated into subprimal pieces and trim. Trim was collected from each primal and separated into groups based on composition of 90, 80, and 50% lean. Zilpaterol hydrochloride increased (P = 0.01) CSW by 6.22 kg and saleable yield by 6.4 kg when included in the diet for 20 d. Furthermore, saleable yield as a percentage of CSW was increased (P = 0.03) 1.18 percentage units when included in the diet for 20 d. Steers fed ZH for 20 d had heavier strip loins (4.47 vs. 4.12 kg, P = 0.02), tenderloins (2.75 vs. 2.49 kg, P = 0.02), and ribeye rolls (5.74 vs. 5.30 kg, P = 0.01) than steers not fed ZH. These advantages are further demonstrated as a percentage of CSW. Strip loins (P = 0.06), tenderloins (P = 0.04), and ribeye rolls (P = 0.04) of ZH-fed steers had a greater percentage of CSW than controls. Zilpaterol hydrochloride also increased the percentage of CSW of the 3 primary components of the round when fed for 20 d. The knuckle was 0.10 percentage units heavier (P = 0.11), the top round was 0.24 percentage units heavier (P = 0.04), and the bottom round was 0.22 percentage units heavier (P = 0.03) in ZH-fed steers when compared with steers not fed ZH. Based on these data, it can be concluded that ZH significantly increased subprimal cutting weights, yields, and percentage saleable yield of calf-fed Holstein steers when fed for at least 20 d before slaughter. Zilpaterol hydrochloride increased percentage of CSW of subprimal cuts from Holstein steers in the round and to a lesser degree in the loin.

Key Words: β-agonist • cutting yield • Holstein • steer • Zilmax • zilpaterol hydrochloride