title: Carcass grading characteristics of serially harvested calf-fed Holstein steers fed zilpaterol hydrochloride.
abstract: Serial harvests were conducted using Holstein steers ( = 110) fed zilpaterol hydrochloride (ZH) for 0 or 20 d prior to harvest. Steers were harvested in 28-d increments beginning at 254 d on feed (DOF) and ending at 534 DOF. After harvest and a 36-h chill period, carcasses were evaluated using grading methods standard for the United States (USDA), Canada (Canadian Beef Grading Association [CBGA]), and Japan (Japanese Meat Grading Agency [JMGA]). No ZH treatment differences ( = 0.81) were detected for 12th-rib fat thickness; however, additional DOF resulted in a daily linear increase ( < 0.01) of 12th-rib fat thickness by 0.004 cm/d. Longissimus muscle area was increased ( < 0.01) by 8.7 cm with ZH supplementation and linearly increased ( < 0.01) 0.08 cm2/d with additional DOF. Calculated USDA yield grade (YG) decreased ( < 0.01) 0.33 units due to ZH treatment and linearly increased ( < 0.01) 0.009 units/d. Steers supplemented with ZH exhibited increased ( < 0.01) CGBA LM width; however, no difference ( = 0.37) was detected in CGBA LM length. No ZH treatment differences ( = 0.64) were observed for CBGA fat class; however, CGBA fat class linearly increased ( < 0.01) by 0.01 units/d. No ZH differences ( ≥ 0.17) were detected for the CBGA estimated lean percentage or YG equations. Evaluation for JMGA occurs at the sixth and seventh rib interface; LM area was 4.6 cm2 greater ( = 0.02) for cattle supplemented with ZH and linearly increased ( < 0.01) by 0.07 cm2/d with additional DOF. Subcutaneous fat thickness was not different among ZH treatments ( = 0.10) but linearly ( < 0.04) increased ( < 0.01) by 0.005 cm/d with additional DOF using the JMGA grading method. No difference ( ≥ 0.21) was calculated between ZH treatments or DOF for JMGA estimated yield. No ZH treatment differences ( = 0.85) were detected in USDA marbling score; however, marbling linearly increased ( < 0.01) 0.07 units/d. These data illustrate the impact of ZH and increasing DOF on economically important carcass grading outcomes used in the USDA, CBGA, and JMGA grading programs.
authors.forename: N D
authors.initials: ND
authors.lastname: May
authors.forename: T J
authors.initials: TJ
authors.lastname: McEvers
authors.forename: L J
authors.initials: LJ
authors.lastname: Walter
authors.forename: J A
authors.initials: JA
authors.lastname: Reed
authors.forename: J P
authors.initials: JP
authors.lastname: Hutcheson
authors.forename: T E
authors.initials: TE
authors.lastname: Lawrence
mesh_terms: D018663:Adrenergic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001823:Body Composition / Q000187:drug effects*; D002170:Canada; D002417:Cattle / Q000502:physiology; D004334:Drug Administration Schedule; D007564:Japan; D008297:Male; D008460:Meat / Q000592:standards*; D014297:Trimethylsilyl Compounds / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D018663:Adrenergic Agents; D014297:Trimethylsilyl Compounds; C475840:Zilpaterol