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How much of the total plant biomass is
expected to be lost duing te season due to
trampling ,
insect , leaf drop ,
disease , and wildlife ?
These are
competing losses that must be considered in the
determination of utilization.
Normally
, 25 percent of the current
year
’
s dry matter is
considered lost through naturai processes
Under season-long grazing .
How much of the herbage produced will
be available for harvest by livestock?
Season of use and forage nutrient
content are major considerations in animal
performance.
The estimated percentage
of the forage actually harvested changes with
the
type
of
grazing
method
used
.indications
are
that
harvest
efficiency
increases
as
the
rotation
interval
is
shortened.
According
to
estimate
,
as
much
as
40
percent
of
the
forage
is
harvested
with
intensive
rotation
systems. If these estimates prove to be
real and animal performance can
be
maintained at or near season-long grazing values ,
increased harvest
efficiency will
result. Specialized intensive-management grazing
programs may increase the relative
amount of forage harvested. The more
intensive
systems
are
normally
used
on
irrigated
,
tamegrass
,
or
annual
pastures. Their use
on rangeland is recommended only when the manager
commits to the higher management level
required.
在放牧季节有多少由于踩踏，虫害，落
叶，病害，野生生物而导致的总植物生物量的
损失是所期望的？
在确定利用率时这些竞争损失必须考虑在内，
通常，
在长季节放牧下，
现年干物质损失
的
25%
被认为是通过自然过程损失的
。
由于家畜牧草生产有多少将是可收获的？
在动物生产性能中主要考虑使用季节和牧草营养含量。
预计的实际收获牧草百分比随
着
放牧方式的类型的改变而改变。
有迹象表明，
收获率虽轮流间隔缩短而增大。
据估计，
多达
40%
的牧草收获于密集的轮牧系统。
如果这些
估计被证实是真实的并且动物生产性能可以被
维持或者接近长季节放牧价值，
结果是收获率增加了。
专业化的集中管理放牧计划可能增加
收获牧草的相对量。
更密集的系统通常用于灌溉，
人工
牧场，
或者是一年生草地。
仅仅当管
理
者致力于更高的管理水平的要求时它们被推荐用于牧场。
Season of use
使用的季节
There
is
an
optimum
season
of
use
for
every
combination
of
plant
and
grazing
animal.
V
egetative
plant
growth
prior
to
seed
stalk
development
is
the
period
of
highest
nutritional
quality
and
highest
animal
performance.
After
seed
stalk
development
, forage
quality
declines.
This is true for both warm and cool
season forages , whether annual or perennial .
Likewise , there
is
a
period
during
the
plants
growth
cycle
when
grazing
pressure
should
be
reduced.
For
warm-season plants, this periond is
during early
vegetative growth ( late
April to early May ) and
again during
reproductive development ( July to frost ). For
cool-season plants it is in early spring
and again in the July-August and early
fall periods . During these periods, heavy grazing
should be
avoided . Reducing the leaf
area of a perennial plant during the late summer
and early fall restricts
its ability to produce foodstuffs for
current growth needs ,
stored food
reserves and root growth .
Each
growing
season
,
approximately
one-third
of
the
root
system
must
be
replaced
by
new
growth due to losses caused by root
pruning , shrink-swell of the soil , and diseases
, Under heavy
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