192
-Foraging Around, Lancaster Farming, Saturday, July 13,2002
Manage Sorghum and Sudangrass
Watch Harvest Conditions, Animal Health Hazards
Marvin Hall
Prof, of Forage Management
Penn State
After last year’s drought,
many producers have
planted a summer-annual
grass (sorghum, sudangrass,
sorghum-sudan hybrid, or
millet) as insurance in case
this year is another cooker.
As we approach harvest time
for these grasses, lets take a
quick look at some harvest
mangement tips.
Both the grain and forage
sorghums are most fre
quently used for silage or
greenchop in a single cut
system, although they can be
grazed if desired. Silage
should be cut when the grain
is in the medium to hard
dough stage. Generally,
whole plant moisture should
be near the desired level for
ensiling at this time. In cases
where maturity is delayed, a
frost may be necessary to
reduce whole plant moistures
to an acceptable level. Diges
tibility of silage made from
the sorghums will usually be
about 90-95 percent of well
preserved corn silage.
The other summer annual
grasses can be used for graz
ing, greenchop, silage, or hay.
When used for grazing,
these grasses must be grazed
at the proper stage of growth
to reduce herd health prob
lems and optimize produc
tion. The best time to graze is
when the plants are between
BUY,
SELL,
TRADE
OR
RENT
THROUGH
THE
CLASSIFIED
ADS
IN
Lancaster
Farming
PHONE:
717-626-11E4
OR
717-394-3047 I
FAX:
717-733-0050
Mon., Tues.,
Wed., Fri.
8 AM to 5 PM
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7AMto 5 PM I
18 and 30 inches tall (six to
eight weeks after planting).
Grazing when the plants are
less than 18 inches tall will
delay regrowth and increase
the chances of prussic acid
poisoning in sorghum, sudan
grass, and sorghum
sudangrass hybrids.
Sufficient animals should be
placed on the pasture area to
graze the grass down in less
than 10 days. Six or more ani
mals per acre may be neces
sary to accomplish this rapid
grazing.
After grazing, clip the resi
due to about 8 inches high to
eliminate old stems and
ensure high quality for the
next grazing period. Do not
graze or clip these grasses too
close (less than 8 inches) be
cause it will weaken and may
kill the plants. It will nor
mally take three to four
weeks for sufficient regrowth
before grazing again.
Grazing can continue on
these grasses until frost, or
even after frost it the plants
are allowed to turn brown
(one week after a killing
frost) before they are grazed.
Do not graze frost damaged
or stunted sorghum, sudan
grass, or sorghum
sudangrass hybrids until they
have been killed (turn brown)
by the frost. If the plants
begin to grow again after
being frost damaged, they
should not be grazed until the
regrowth is 18 inches tall or
the entire plant is killed by
!■ BrfMSan T 7
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frost and turns brown,
Summer annual grasses
are ideal for greenchop. Use
the same harvest precautions
for greenchop as used when
grazing to avoid prussic acid
poisoning. Cut the plants
down to about 8 inches.
Greenchop harvesting should
not begin until the plants are
at least 18 inches tall, how
ever, it should begin early
enough to complete harvest
ing before the plants begin to
head. Harvesting after the
plants have headed will
reduce dry matter intake and
milk production in cows, and
regrowth potential of the
plants.
Sudangrass, sorghum
sudangrass hybrids, and
millet should be harvested for
silage when they are between
36 and 48 inches tall, or in the
boot to early-head stage,
whichever comes first. At this
maturity, they contain exces
sive moisture for proper en
siling and should be wilted
(mowed and allowed to par
tially dry in the field) before
ensiling.
Greatest hay yields are ob
tained if the annual grasses
are harvested when the seed
is in the soft-dough stage.
However, proper drying is
difficult at this stage. There
fore, harvest for hay is rec
ommended during the
vegetative stage before the
heads emerge or the plant
reaches a-height of 4 feet. A
hay conditioner should be
used to mow and crush the
5’ SURE STAND SEEDER
This 5’ model has a single box with two compartments.
The capacity of the front box (for chaffy seeds) is 1-1/4
bushels, the rear box (for legumes) holds 3/4 bushel.
lhis_model fits category 1 three point hitch.
stems for rapid, uniform
drying. It is extremely diffi
cult to field cure these grasses
adequately for safe storage as
hay.
Potential Animal Health
Hazards
Prussic acid poisoning is a
major concern when feeding
sorghum, sudangrass, or
sorghum-sudangrass hybrids.
These species contain vary
ing amounts of cyanogenic
glucosides. In the rumen,
these compounds are con
verted into prussic acid
which is readily absorbed into
the blood stream where it in
terferes with respiration. If
prussic acid is present in the
rumen and absorbed rapidly
enough, the animal will soon
die from respiratory paraly
sis.
Forage species and varie
ties may be selected that con
tain low levels of cyanogenic
glucosides. Piper sudangrass
has low levels and millet is
free of these compounds. The
management practices de
scribed below can also reduce
the risk of prussic acid poi
soning from sorghum, sudan
grass, and sorghum
sudangrass hybrids:
• Graze or greenchop only
when they are greater than 18
inches tall.
• Don’t graze plants
during or immediately after a
drought when growth has
been reduced.
• Don’t graze on nights
when a frost is likely. High
levels of the toxic compounds
are produced within hours
after a frost occurs.
• Don’t graze after a killing
frost until the plant is dry
(the cyanogenic glucosides
usually dissipate within sev-
eral days).
• Don’t graze after a non
killing frost until regrowth is
greater than 18 inches.
• Delay feeding silage for
six to eight weeks after ensil
ing.
Nitrate poisoning can be a
problem under conditions of
high nitrogen fertilization,
heavy manure applications,
drought, or overcast weather,
when the plants can accumu
late high levels of nitrates.
When plants containing high
levels of nitrates are eaten,
the nitrates are converted
into nitrites faster than they
can be properly utilized by
the animal. These excessive
nitrites are absorbed into the
bloodstream and alter the
blood so that it can not carry
oxygen. This causes rapid
breathing, fast and weak
heartbeat, muscle tremors,
staggering, and ultimately
death if corrective steps are
not taken.
The same precautions for
prussic acid poisoning will
help prevent nitrate poison
ing. Millet can cause nitrate
poisoning but not prussic
acid poisoning. High nitrate
levels will persist in forages
cut for hay, but will be re
duced by about half if the
crop is ensiled.
Poisoning of horses fed sor
ghum, sudangrass, or
sorghum-sudangrass hybrids
has also been reported. The
exact cause of this poisoning
is not known. Affected horses
exhibit a staggering gait,
urine dribbling, and aborting
in pregnant mares. There is
currently no treatment for
this poisoning and affected
horses rarely recover. Don’t
feed horses any of these
summer-annual species.
Contact your local
dealer for details.
Pennsylvania
ADAMSTOWN
Adamstown Equip. Inc
717-484-4391
ALLENJOVyN
Lehigh Ag Equipment
610-398-2553
l-quip. Co,
610-845-2911
CRESSON& BELLWOQD
Hines Equipment Co.
814-886-4183
814-742-8171
LEBANON
Umßerger's of Fontana
717-867-5161
OAKLAND MILLS
Peoples Sales & Service
717-436-2735
ITkeville Equipment, Inc.
610-987-6277
OAKLAND MILLS
PeopTes Sales & Service
717-436-2735
QUARRVVILUE
Grumedi Farm Service
717-786-7318
Snyder, Inc.
570-386-5945
RISING SUN
Ag Industrial Equipment
410-658-5568
New Jersey
ELMER „
Pole Tavern Equip.
Sales Corp.
856-358-2880