In an 84-day pasture/132-day finishing
study using 480 crossbred steers (675 lb),
Ralgro® increased (P<.05) pasture gains 9.3%
compared to nonimplanted controls. Gains of
Synovex-S®-implanted steers were intermediate.
Pasture treatments were split into two
finishing-phase implant treatments: Synovex®
Plus™ or initial Ralgro with a Synovex Plus
reimplant on day 56. No interactions occurred
between pasture and finishing implants with
respect to finishing performance or carcass
traits. Steers on the Synovex Plus treatment
gained 11.7% faster and 7.9% more efficiently
(P<.01) during the first 56 days of the finishing
phase than the Ralgro-implanted steers.
However , when those steers were reimplanted
with Synovex Plus, they gained 22.2% faster
and 21.1% more efficiently (P<.01) during the
last 76 days. Over the entire 132-day finishing
phase, the feedlot reimplant program improved
rate (4.0%; P<.06) and efficiency (7.5%; P<.01)
of gain compared to Synovex Plus alone.
Overall , gains and intakes during the finishing
phase were similar for all pasture implant treatments.
However, control pasture steers were
4.5% more efficient (P<.08) than Ralgro and
Synovex steers during the finishing phase.
Neither pasture or finishing implant treatment
influenced carcass traits. This study indicates
that implanting during grazing may reduce feed
efficiency during the finishing phase, especially
when a feedlot reimplant program is not used.
However, this finding disagrees with several
previous research studies where pasture
implantation had no effect on feedlot performance.
