title: Effects of ovariectomization and ractopamine hydrochloride inclusion on heifer feedlot performance, meat yield, and tenderness of select muscles.
abstract: Forty-eight British cross heifers were used to examine the effects of ovariectomization (OVX v. intact; INT) and ractopamine-HCl inclusion (0 or 0.41 mg/kg of BW day(-1); NORAC or RAC) for the final 31 days on performance, meat yield, and tenderness of select muscles. Ractopamine supplemented heifers had heavier BW (P≤0.05) and greater dressing percent than NORAC. Dressing percent was also greater (P<0.01) for INT v. OVX. LM area tended to be larger for RAC (P=0.07) and was larger for INT (P=0.05). Neither ractopamine inclusion nor sex class affected (P>0.08) organ weights or percent intramuscular fat. Ractopamine inclusion increased (P≤0.05) subprimal weight for the shoulder clod and bottom round. However, ractopamine inclusion and sex class had minimal effects on subprimal yields or slice shear force. Heifers receiving ractopamine had increased BW, DP, carcass weight and select subprimal weights without impacting meat quality. Ovariectomization did not influence the affects of ractopamine supplementation.
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Athens 30602, United States.
authors.forename: C S
authors.initials: CS
authors.lastname: Talton
authors.forename: A M
authors.initials: AM
authors.lastname: Stelzleni
authors.forename: J S
authors.initials: JS
authors.lastname: Shook
authors.forename: G M
authors.initials: GM
authors.lastname: Hill
authors.forename: C R
authors.initials: CR
authors.lastname: Kerth
authors.forename: M
authors.initials: M
authors.lastname: Pence
authors.forename: T D
authors.initials: TD
authors.lastname: Pringle
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001835:Body Weight; D002417:Cattle; D019587:Dietary Supplements; D005260:Female; D063427:Food Quality; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D009929:Organ Size; D010052:Ovariectomy; D010627:Phenethylamines / Q000494:pharmacology*
chemical_list: D000318:Adrenergic beta-Agonists; D010627:Phenethylamines; C060897:ractopamine
keywords: Carcass characteristics; Heifer; Ovariectomization; Ractopamine-HCl; Tenderness; Yield