Four hundred fifty heifers (846 lb) were
used in a 126-day experiment to investigate the
effects of feeding two microbial additives,
Lactobacillus acidophilus BG2FO4
(MicroCell) and Propionibacterium
freudenreichii P-63 (MicroCell PB), alone or
in sequence, on feedlot growth performance and
carcass characteristics. A 21-day step-up
period preceded heifers being placed on a final
finishing diet containing 10% corn silage, 42%
steam-flaked corn, 42% high-moisture corn,
3% soybean meal, and 3% mineral supplement.
Premeasured amounts of microbial additive
were mixed with water before being mixed
directly with the total ration. Treatments consisted
of 1) no microbial additive; 2) MicroCell
for the entire period; 3) MicroCell PB for the
entire period; 4) MicroCell for 28 days then
MicroCell PB for the remainder of the period;
and 5) MicroCell PB for 28 days then
MicroCell for the remainder of the period.
Feeding MicroCell for 28 days and then
MicroCell PB for the remainder of the feeding
period resulted in significant improvements
(P<.10) in daily gain and feed efficiency.
