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Online Journal of Veterinary Research

(Including Medical and Laboratory Research)

Established 1994
ISSN 1328-925X


Volume 26 (11): 777-787, 2022.

Effect of zilpaterol-hydrochloride on carcass quality, myosin heavy chain and mRNA β-adrenergic receptors in cattle.


Amir Hossein Asgari Safdar.


Young Researchers and Elite Club, Baft Branch, Islamic Azad University, Baft, Iran.



Asgari Safdar AH., Effect of zilpaterol-hydrochloride on carcass quality, myosin heavy chain and mRNA β-adrenergic receptors in cattle, Onl J Vet Res., 26 (11): 777-787, 2022. Author describes effect of dietary 8.38 mg/kg zilpaterol hydrochloride (ZH), 120 mg trenbolone acetate (TBA) and 24 mg estradiol-17β (E2) on mRNA β-adrenergic receptors I and II, calpastatin and I, IIA, and IIX myosin heavy chain isoforms. Three groups of 24 steers per pen each, were supplemented daily for 30 days 8.4mg/kg/day ZH (1), 120 mg/kg TBA with 24 mg/kg E2 (2) or 8.4mg/kg ZH with 120mg/kg TBA with 24 mg E2 (3). Controls were not treated (4). At slaughter, semimembranosus muscle tissue was excised for RNA from 4 carcasses per pen. Administration of ZH during the last 30 days of feeding boosted (P < 0.01) ADG, G: F, HCW, and LM area; decreased (P< 0.01) 12th rib fat depth and marbling; and improved (P < 0.01) yield grade. Treatment had no effect on β1- AR mRNA levels, but there was an increase (P = 0.01) in β2-AR mRNA levels due to ZH inclusion. Myosin heavy chain-I (MHC-I) mRNA levels were unaffected by treatment. Feeding ZH last 30d prior to harvest, increased (P < 0.01) mRNA concentrations of MHC-IIX in semimembranosus muscle of steers. These data indicate the combined use of ZH and RS may boost live and carcass gain in finishing feedlot steers and affects mRNA MHC isoforms to faster glycolytic fiber type in bovine skeletal muscle.


Key Words: Zilpaterol-HCl, mRNA, myosin, steers.