Des Moines, Iowa
July 6, 2009
Processed corn kernels in silage
are readily digested, allowing cows to absorb more energy for
milk production, say experts at
Pioneer Hi-Bred, a DuPont business. Producers can improve
starch digestibility in ruminants by adequately processing
grains being fed and by thoroughly processing corn kernels
during silage harvest.
"More than half of the digested energy in corn silage comes from
the starch and sugar; and these come primarily from the corn
kernel," says Fred Owens, Pioneer senior research scientist.
"Therefore, it is vital for producers to process corn silage to
obtain high starch and energy availability."
The smaller the kernel particles in corn silage, the more easily
they are digested both in the rumen and intestines. Larger
particles or whole kernels often pass through the tract
undigested.
"Energy from feed becomes available only if the material is
digested," says Owens. "Whole kernels may pass through the
digestive system intact. Sacrificing starch digestibility also
sacrifices nutritional value and efficiency of production."
Like starch in high moisture corn grain, starch from corn silage
is digested primarily in the rumen. Although starch that is very
rapidly digested in the rumen can cause acidosis,
over-processing of grain included in the diet, not of the
silage, and inadequate forage intake usually are the root causes
of acidosis. Through increasing starch availability, kernel
processing corn silage can reduce the amount of grain that needs
to be fed.
"If a producer sees whole kernels or even half kernels in
silage, digestibility of starch from that silage is less than
ideal," says Owens. "Chopping length at harvest has a limited
impact on starch digestibility; gap setting on the kernel
processing rolls is the primary driver. A gap setting of 1 mm
for the processing rolls is considered ideal. To be well
digested, processed particles should be less than one-quarter of
the size of the kernel."
Corn silage that has not been kernel processed is another
matter. For unprocessed corn silage or when the processor
setting has allowed whole kernels to come through, kernel dry
matter and kernel hardness can impact starch digestibility.
Starch in unprocessed corn silage can have digestibility below
90 percent compared to more than 95 percent for processed
silage.
Yet, compared with dry grain, grain in corn silage generally has
high starch availability because of the fermentation process.
Starch availability also increases during time in the silo. Corn
silage several months old has higher feeding value than silage
fed within a month after harvest.
"While it is recommended to stay within the suggested moisture
bounds during corn silage harvest for ideal fermentation and
compaction in storage structures, letting corn silage become a
bit more mature certainly increases both starch content and
silage yield," says Owens. "But for more mature silage with
drier grain, kernel processing of the silage during harvest
becomes absolutely essential."
Silage hybrids should be selected first for maturity and to
match one's agronomic practices. Then, because hybrids can have
a large impact on yield and starch content, selection should be
based on yield, tonnage, starch and fiber digestibility.
"If a producer sees whole kernels passing through cattle, kernel
processing has failed," says Owens. "Effectiveness of processing
must be monitored during harvest. The only alternatives are
reprocessing the silage at feeding time or delaying silage
feeding until kernels have been softened by fermentation."
For more information on starch digestibility or processing,
contact your local Pioneer representative. To learn more about
how Pioneer can help you plant, grow, harvest, store and feed
higher-yielding, better quality forage crops and maximize their
value, visit our Web site at
www.pioneer.com/forages.
Pioneer Hi-Bred, a DuPont business, is the world's leading
source of customized solutions for farmers, livestock producers
and grain and oilseed processors. With headquarters in Des
Moines, Iowa, Pioneer provides access to advanced plant genetics
in nearly 70 countries.
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in 1802, DuPont puts science to work by creating sustainable
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