title: Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on longissimus muscle shear force and sensory attributes of beef steers.
abstract: Effect of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on LM shear force and sensory attributes was determined using pens (n = 40) British × Continental crossbred steers randomly allocated to one of the following treatments: control; RH fed at 200 (RH 200) or 300 mg • steer(-1) • d(-1) (RH 300), or 400 mg • steer(-1) • d(-1) (RH 400) top-dressed for the final 30 d of feeding; or ZH fed at 7.5 mg/kg, beginning 23 d before slaughter with a 3-d withdrawal. Two replicates (pens) per treatment were represented in four blocks. Eighteen carcasses per pen were randomly selected and one 5-cm LM sample was removed from both carcass sides to be used for shear force and sensory evaluation. Samples were aged for 14 d, frozen at -28.8 °C, and cut into 2.5-cm steaks. All steaks were cooked to an internal temperature of 71.1 °C before being evaluated for Warner-Bratzler shear force (WBSF), slice shear force (SSF), or being fed to trained sensory panelists. Increasing dose and potency of β-agonist increased WBSF by 4 to 17% and SSF by 5 to 24% (P < 0.05). Steaks from steers fed ZH had higher WBSF and SSF values compared with all other treatments (P < 0.05), whereas steaks from controls and steers fed RH 200 were not different (P > 0.05). Probability of steaks failing to meet shear force standards to be certified tender (WBSF <4.4 kg, SSF < 20 kg) was increased from an initial probability of <0.06 in steaks from steers in the control treatment to 0.10 to 0.20 in steers fed RH 400 or ZH (P < 0.05). No difference was detected in panel ratings for overall tenderness of steaks from steers fed RH 200 compared with controls (P > 0.05). Steaks from steers fed RH 300 and RH 400 were comparable for all sensory attributes; however, both RH 300 and RH 400 were rated lower for overall tenderness than controls (P < 0.05). Panelists failed to detect differences in overall tenderness of steaks from steers fed RH 400 and ZH (P < 0.05). Panelists detected no difference in flavor profile or juiciness among treatments (P > 0.05). Results from this study indicated β-agonists negatively affected beef tenderness and these effects may be more noticeable in steers supplemented with ZH and higher doses of RH.
authors.affiliation: Center for Meat Safety and Quality, Colorado State University, Fort Collins 80523-1171.
authors.forename: T S
authors.initials: TS
authors.lastname: Arp
authors.forename: S T
authors.initials: ST
authors.lastname: Howard
authors.forename: D R
authors.initials: DR
authors.lastname: Woerner
authors.forename: J A
authors.initials: JA
authors.lastname: Scanga
authors.forename: D R
authors.initials: DR
authors.lastname: McKenna
authors.forename: W H
authors.initials: WH
authors.lastname: Kolath
authors.forename: P L
authors.initials: PL
authors.lastname: Chapman
authors.forename: J D
authors.initials: JD
authors.lastname: Tatum
authors.forename: K E
authors.initials: KE
authors.lastname: Belk
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D008297:Male; D008460:Meat / Q000592:standards*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D010627:Phenethylamines / Q000494:pharmacology*; D033081:Shear Strength; D014297:Trimethylsilyl Compounds / Q000494:pharmacology*
chemical_list: D000318:Adrenergic beta-Agonists; D010627:Phenethylamines; D014297:Trimethylsilyl Compounds; C475840:Zilpaterol; C060897:ractopamine