A pasture/feedlot field study was conducted
to evaluate the effects of a single
Ralgro® implant during the stocker phase on
steer grazing performance and subsequent
feedlot performance and carcass merit. A
total of 2,764 steers of Mexican origin averaging
449 lb were assembled in Texas and
shipped to Kansas, where they grazed on
three intensively-early-stocked Flint Hills
pastures. At initial processing, the steers
were individually weighed and randomly
assigned to either a non-implanted control
group or a Ralgro implant group. Ralgro
steers gained more (23 lb; P<0.01) than
controls during the 82- to 93-day grazing
phase. Following the grazing phase, all steers
were shipped to a commercial feedlot in
southwestern Kansas where steers from each
pasture were individually weighed and given
a single Component E-S® implant. Immediately
after processing, steers from each
pasture were sorted into either a light- or
heavy-weight pen, regardless of pasture
implant treatment, resulting in six feedlot
pens. Days on feed ranged from 127 to 197.
Control steers gained faster (P<0.01) during
the feedlot phase; however, Ralgro steers had
higher cumulative weight gains across the
combined pasture and feedlot phases
(P<0.01) and averaged three fewer days on
feed (P<0.05). There were no significant
differences for marbling, fat thickness, ribeye
area, KPH fat, or yield grade. Ralgro
steers had lower (P<0.05) quality grades
because of a higher incidence (P<0.001) of
steers with B and C carcass maturities.
