Objective: To evaluate effects of ractopamine
HCl (RAC) dose and treatment
period on growth performance and carcass
composition in a commercial finishing
environment.
Materials and methods: In Experiment
One, a total of 880 pigs (PIC L337 × C22;
initially 106.5 ± 0.5 kg) were allotted to
four treatments, including doses of 0, 5.0,
7.5, and 10.0 ppm of RAC for 21 days
before slaughter. In Experiment Two,
1035 gilts (initially 103.2 ± 0.62 kg) were
allotted to nine treatments. Treatments
included doses of 5 or 10 ppm RAC for 7,
14, 21, or 28 days before slaughter and a
control treatment without RAC.
Results: In Experiment One, average daily
gain (ADG), gain-to-feed ratio (G:F), and
carcass yield increased (linear, P < .05)
with increasing dose of RAC. The largest
numeric differences were observed as RAC
dose increased from 0 to 5 ppm. In Experiment
Two, ADG and G:F were greater
(P < .05) for pigs fed 5 ppm RAC for 14,
21, or 28 days and for pigs fed 10 ppm
for all treatment periods than for control
pigs. Carcass yield was greater in pigs fed 10
ppm RAC (P < .05) than in pigs fed 5 ppm
RAC or in the controls. RAC dose (5 ppm
versus 10 ppm) did not affect carcass lean
measures (P >
.16).
Implications: Feeding RAC at 5 to 10
ppm for 14 to 28 days before slaughter
increases ADG, G:F, and carcass yield
of pigs reared in a commercial finishing
environment.
