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GRAZING MANAGEMENT
Dr. Marvin H. Hall
Penn State
Grazing management involves
the control of grazing animals on
pasture. The two most important
tools for influencing the level of
animal output under grazing are
concentration of animals per acre
(stocking rate) and the system of
grazing management (which will
be discussed in a subsequent
article).
Grazing Pressure And
Stocking Rate
The closeness to which a pas
ture is grazed is defined as grazing
pressure. Grazing pressure is
affected by both stocking rate
(animals per acre) and available
forage (pounds of forage per acre).
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SCHROCK
FARM EQUIPMENT
Route 1, Box 2568
Oakland, MD
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r TEFTRISES, INC.
' 178 Oliver Shop Road
p La Pata, Md
ANDERSON
TRACTOR SALES
4600 Breldenßaugh Lane
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Glenarm, Md.
High grazing pressure causes
close grazing and short pasture
stubble. Animal performance is
reduced because animals are
forced to consume all portions of
the pasture, including the poorer
quality forage. Excessively high
grazing pressure results in
overgrazing.
Low grazing pressure refers to
selective grazing, with unlimited
forage available to animals (Fig
ure 1). Animal production rates
(gain per head per day, etc.) will
usually be high at low grazing
pressure. Very low grazing pres
sure, or under grazing, results in
wasted forage and consequent
poor animal production per acre.
An optimum grazing pressure is
one in which available forage
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Bonnville, NY
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would be analogous to the quanti
ty of forage offered daily to ani
mals in confinement when rations
are balanced. In order to maintain
an optimum grazing pressure, it is
important to adjust stocking rate
so that available forage is main
tained within an optimum range.
Available forage not only influ
ences stocking rate, but can also
affect dry matter intake. As the
amount of forage decreases,
intake per animal decreases.
Reduction of available forage
from 1000 to 500 pounds per acre
has been shown to reduce average
intake by almost 40 percent. For
optimum grazing, available pas
ture should be maintained at 1,000
to 1,500 pounds of dry matter per
acre. On average, a 3- to 4-inch
bluegrass/white clover sward will
have about 1,000 pounds of dry
matter per acre. In tall grasses and
legumes, this may be about 6 to 8
inches high.
Unfortunately, not all available
forage in a pasture is utilized.
Some of the forage will be
trampled or fouled by urine or
manure and remain uneaten. The
amount of available forage which
is consumed is called utilized for
age. At high grazing pressures,
animals are forced to consume
more of the available forage
resulting in a relatively high (grea-
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Route 1, Box 38A
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Watsontown, PA
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TRACTOR SALES
636 B S. Main St.
Shrewsbury, PA
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RO 2. Box 160
Meadville, PA
High
S Medium
1
Low
Low
Neg
Figure 1. Effect of grazing pressure on production per animal and per acre.
ter than 80-percent) utilization
rate. At low grazing pressures the
animals will refuse to eat portions
of the forage thus decreasing the
utilization rate. As the length of
the grazing period increases (low
er grazing pressure), the percent
utilization decreases.
Grazing pressure will not only
affect animal performance, but
will also affect the plant species in
a pasture. Long periods of low
grazing pressure commonly cause
loss of legumes from the stand. At
the other extreme, long periods of
high grazing pressure can result in
a temporary or long-term decrease
in pasture production. High to
excessive grazing pressure for
Ag Tech
GREENSBURG (Westmore
land Co.) The Westmoreland
Agricultural Fair, Penn State Uni
versity, and Westmoreland Coun
ty Cooperative Extension Service
announce the second Southwest
Pennsylvania Ag Technology Day
on Thursday, August 26.
Last year, 23 commercial exhi
bitors participated and, even
though it rained, farmers from
Fayette, Indiana, Somerset, Wash-
Morton
• Horse Barns
• Riding Arenas
•Garages
•Warehouses
*
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gpnißiinlfc*
BUILDINGS, INC
M \Sh Excellence Since 1903
3368 York Rd. CONTACT: p. O . Box 126,
Gettysburg, Philllpsburg,
PA 17325 NJ 08865
717/624-3331 908/454-7900
Cali or who today
lor rmra Information
Output/Head
Available Pasture
Medium . Low
Medium High
Stocking Rate
long periods with little or no
opportunity for selective grazing
will also cause low animal intake
and low gain rates.
Short periods of high grazing
pressure can serve useful pur
poses. One to 2 weeks at high
grazing pressure, three or four
times through the grazing season,
can help maintain legumes in the
stand and utilize forage that might
otherwise be wasted. It is impor
tant not to expose lactating cows
or growing animals (calves, year
lings, and lambs) to long periods
of high grazing pressure. Beef
cows and ewes can tolerate high
grazing pressure after breeding.
Day Set
ington, and Westmoreland coun
ties attended. Both exhibitors and
farmers thought it a worthy event.
Time for agribusiness exhibi
tors to make short presentations to
the group assembled is allotted.
Ag Technology Day is held in
conjunction with the Westmore
land Fair, a short distance from the
main fair activities. Farmers pay
no admission to participate in Ag
Technology Day.
BUILDINGS
Since 1903
•Offices
•Shops
• Equipment Storage
• Aircraft Hangars
1-800-447-7436
Output/Acre
V. Lo'
V. High \
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Illinois oniy»gj
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