title: Response of barrows to space allocation and ractopamine.
abstract: An experiment using 264 crossbred barrows was conducted to examine the interaction between space allocation and dietary ractopamine addition on pig performance and carcass characteristics using a 2 x 2 factorial arrangement of treatments. Treatments were 0.55 (19 pigs per pen) or 0.74 (14 pigs per pen) m2/pig from start (29.7 +/- 0.1 kg BW) to slaughter (108 kg BW) in a fully slatted facility and 0 or 10 ppm (as-fed basis) ractopamine for 28 d before slaughter. There were few treatment interactions. Pigs given 0.55 m2/pig had a lower ADG (P = 0.010), ADFI (P = 0.088), 10th-rib backfat depth on d 86 (P = 0.010), and carcass loin muscle depth (P = 0.011) than pigs given 0.74 m2/pig. There was no difference in feed conversion (P = 0.210) as a result of space allocation. Pigs fed diets containing 10 ppm ractopamine had decreased (P = 0.004) ADFI and improved (P = 0.001) feed conversion efficiencies for the 28-d feeding period, along with greater loin depth (P = 0.005) and carcass lean percent (P = 0.001). The improvements in 28-d carcass lean growth associated with feeding 10 ppm ractopamine resulted in an improvement in overall daily fat-free lean gain (P = 0.046). Under these experimental conditions, the response to dietary ractopamine was similar for crowded and uncrowded pigs.
authors.affiliation: Haskell Agricultural Laboratory, University of Nebraska, Concord 68728, USA. mbrumm1@unl.edu
authors.forename: M C
authors.initials: MC
authors.lastname: Brumm
authors.forename: P S
authors.initials: PS
authors.lastname: Miller
authors.forename: R C
authors.initials: RC
authors.lastname: Thaler
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000821:Animal Feed; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D003441:Crowding; D004032:Diet; D006799:Housing, Animal; D008297:Male; D010627:Phenethylamines / Q000008:administration & dosage / Q000494:pharmacology*; D013552:Swine / Q000254:growth & development*
chemical_list: D000318:Adrenergic beta-Agonists; D010627:Phenethylamines; C060897:ractopamine