1Treatments include: 1) Natural—no antibiotics, ionophores, growth implants
or beta-agonists (NAT), 2) Conventional—fed tylosin, monensin, received
growth implant, no beta-agonist (CONV), and 3) Conventional w/
zilpaterol—fed tylosin, monensin, received growth implant, fed zilpaterol
hydrochloride (87.6 mg/steer last 20 days on feed; CONV-Z).
2All values except for DM are on a 100% DM basis. Samples were
chemically analyzed at a commercial laboratory (Servi-Tech Labs Inc.
Dodge City, KS). Samples were composited from weekly samples collected
across trial period and analyzed in duplicate.
3Ration was analyzed to contain 6.76 mg/kg (90% DM basis) zilpaterol
hydrochloride, which was fed for the last 20 d on feed, followed by a 3-d
withdrawal.