Page 12—Foraging Around, Lancaster Farming, Saturday, November 1, 1997
Now May Be A Good Time To ‘Brush Up’ On Pasture Terminology
Dr. Marvin H. Hall
Extension Forage Specialist
Penn State
Learning the “language of pasture”
is a prerequisite to learning about and
improving pasture management skills.
Pasture forage is described as her
bage or the above-ground plant mater
ial of grasses, legumes, weeds, and
shrubs. Herbage mass is the total
amount of herbage per unit area mea
sured to ground level.
Herbage mass is expressed in terms
of pounds of dry matter per acre (lbs
DM/a). A pasture sward is comprised
of all the plants in the pasture. Lives
tock are unable to consume all of the
herbage present because the jaw, teeth
and tongue actions during grazing
physically restrict how closely the ani
mal can graze to ground level.
In addition, the animal is able to
selectively graze within the sward, and
less palatable plants or parts of plants
may be avoided. Selectivity is depen
dent on grazing pressure which defines
the rate of disappearance of herbage
material. Under lax grazing pressure
there is a slow decline in herbage mass
and animals are able to exercise a high
degree of selectivity. If high grazing
pressure is applied, selectivity is
reduced.
Both grazing pressure and the resi
dual amount of herbage that remains
after grazing (post-grazing herbage
mass, or residual herbage mass (lb
DM/a)), can be controlled by the far
mer. In general, as residual herbage
mass (often termed residual dry matter
on RDM) is lowered per animal,
intake of herbage is reduced and, in the
absence of supplements, animal per-
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formance is. lower.
Many grazing management guide
lines describe the relationship between
minimum RDM and livestock produc
tivity. Sward surface height (SSH),
which is an alternative method for
defining grazing management, is the
average height of green leaves in the
sward canopy. As SSH decreases, ani
mal intake decreases.
Successful pasture managers are
familiar with these relationships and
use this information when making
decisions to shift animals between
paddocks. The herbage available (lb
DM/head/day) for grazing refers to the
difference between the total amount of
herbage present (i.e. herbage mass)
and the amount of herbage left after
grazing (i.e. the RDM). Herbage avail
able should not be confused with the
term herbage allowance, which
defines the amount of herbage per ani
mal to ground level on a daily basis
(i.e. lb DM/hd/d).
Herbage allowance values include
the post-grazing residual herbage and
arc always greater than the herbage
available to livestock. Multiplying the
herbage available by the area to be
grazed yields the total amount of her
bage available per paddock; dividing
the herbage available by the number of
animals provides the amount of her
bage available per animal (normally
this is in terms of lb DM/hd/d).
There are numerous terms used to
describe grazing management or the
manner in which a fanner controls the
grazing of livestock to achieve specific
production goals. Controlled grazing
occurs when grazing is regulated to
achieve a desired result.
Intensive grazing attempts to max-
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imize the productivity of animals and
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and management. This contrasts with
extensive grazing where a low level of
inputs and usually a large area of land
per animal. The animals graze the
designated area throughout the time
period when grazing is allowed. The
pastures receive no rest (leaving an
area ungrazed or unharvested for a
length of time) from grazing.
Under intermittent grazing, pastures
are grazed for indefinite periods at
specified or irregular intervals. Rota
tional, strip, sequence, mob, short
duration, and creep grazing are all
forms of intermittent grazing.
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Geraldine Kessel
Extension Specialist
West Virginia University
Extension Service
You can double your benefits by
mowing weedy pastures.
One benefit is that mowing prevents
or slows down seed production of
weeds. The second benefit is that
mowing removes seed heads so the
pastures can produce new, tender
regrowth.
Weeds rob water and nutrients
needed by pasture plants. They also
shade the other plants and slow their
growth. Some weeds, such as thistles,
prevent cattle from grazing large areas
because of their spiny leaves.
If possible, graze a pasture heavily
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Set stocking, or the practice ot
allowing a fixed number of animals on
an area of land for the entire grazing
period, is a form of continuous grazing
management. The number of animals
on a grazing area for a specified period
of time is the stocking rate.
There are a lot more terms related to
pastures and their uses, but we have
discussed most of the ones that you
will encounter. The main purpose of
becoming familiar with terminology is
that it helps communication.
Scientific papers, conference pre
sentations, news articles, workshop
courses, and advice from consultants
can be interpreted and applied much
more readily if you understand the
“language.”
just before mowing to use all the feed
available. This is especially true with
beef cattle. In many cases die animals
will eat some of the weeds and tall
grasses that would be wasted.
Mow pastures closely. Cutting to a
height of 2 to 3 inches will remove the
mature growth. This cutting manage
ment helps keep clover in pastures and
promotes fast growth. If you’re con
cerned that dry weather will prevent
regrowth, mow only a third to a half of
your pastures every 10 days to two
weeks.
Where possible, save excess spring
and summer growth for hay. Some far
mers get enough hay from pasture
mowing to feed their cows all winter.
By doing this, you can use all the for
age you produce for grazing or hay.
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