Five hundred seventy-two crossbred beef
heifers were used to compare gain and feed
efficiency of cattle consuming restricted
quantities of energy-dense growing diets
containing varying concentrations of
Rumensin® and Tylan®. Growing treatments
consisted of providing Rumensin at 30 grams
per ton of dry matter (R30), or 250 mg per
head per day (R250). A third treatment
consisted of a Rumensin/Tylan combination,
providing 250 and 90 mg per head per day of
Rumensin and Tylan, respectively
(R250/T90). Average daily gain and feed
efficiency during the growing phase were not
different (P>0.90) among treatments. Heifers
that received R250/T90 during the growing
phase exhibited lower dry matter intakes
(P<0.05) during the finishing phase. Although
not significant (P>0.50), R250/T90
increased finishing-phase feed efficiency by
6.1 and 3.5% compared to R30 and R250,
respectively. Liver abscesses were lower
(P<0.10) for R250/T90 and R30 than R250.
