Zilpaterol hydrochloride lowers marbling score by dilution of marbling and depression of intramuscular adipocyte volume in M. longissimus dorsi of beef steers

Abstract 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. Crossbreed steers were treated with ractopamine hydrochloride (RH; 28 d) or ZH; 20 d) or no β-adrenergic agonist (CON). ZH increased LT cross-sectional area (P