Zilpaterol hydrochloride lowers marbling score by dilution of marbling and depression of intramuscular adipocyte volume in M. longissimus dorsi of beef steers.
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We hypothesized that zilpaterol hydrochloride (ZH) depresses marbling scores in beef cattle by dilution of the intramuscular (i.m.) adipose tissue in the longissimus thoracis (LT) by increased muscle cross-sectional area. Crossbred steers were treated with ractopamine hydrochloride (RH; 28 d) or ZH (20 d) or no -adrenergic agonist (CON). ZH increased LT cross-sectional area (P<.001) and depressed rib fat depth (P<.001), USDA marbling score (P<.05), percent LT lipid (P<.02), total lipid in a 2.54cm-thick LM steak (P<.05) and most LT lipid fatty acids (P.05),but had no effect on mean i.m. adipocyte volume (P=.15). ZH increased the relative volume proportion of smaller i.m. adipocytes (250 to 500 pL) and decreased the proportion of larger i.m. adipocytes (2000 and 3000 pL) (P<.05). We conclude that ZH reduces marbling score both by dilution of the marbling and a depression of i.m. adipocyte relative volumes.
author list (cited authors)
Gonzales, C. L., Lawrence, T. E., Hutcheson, J. P., & Smith, S. B.
complete list of authors
Gonzales, Carolina L||Lawrence, Ty E||Hutcheson, John P||Smith, Stephen B