|
|
Forage and Pasture
Forage Management Guides
Self-Study Guide 5: Utilization of Forages by Beef Cattle
Forages in the form of pasture, hay, and silage supply over 80 percent of the
nutrients required to produce a beef animal. Since most of the concentrate feed
is fed during the finishing phase, forages provide an even higher percentage of
nutrients consumed during the cow-calf and stocker phases. In Arkansas, careful
management of pastures can result in green forage being available nearly
year-round. Allowing cows to harvest the forage themselves from pastures is the
most economical and convenient approach to forage management. However, forage
stored as hay or silage will be necessary in most operations to support cattle
during periods when pasture production is inadequate to meet livestock
nutritional needs.
Forage management decisions are always influenced by the need to find an
acceptable compromise between yield and forage quality. These two factors
require different types of management to be maximized separately. Forage yield
(tons per acre) and plant persistence are usually maximized when plants are
harvested at mature stages of growth. Forage quality, however, is usually
highest when plants are harvested in a young, leafy stage of growth, at which
point forage will be high in protein and digestibility and low in fiber. Cattle
do not need to eat as much of high quality forage to gain the same amount of
weight as when they are fed low quality forage. The producer’s challenge is to
manage forages and cattle in a way that optimizes both forage performance
(yield, quality, and persistence) and animal performance (weight gain per animal
or gain per acre, health, and reproductive performance).
When planning a forage system, the nutritional needs of the cattle being
raised must be considered. The producer may decide to match the forages to the
desired cattle, or to match the cattle to the existing forages. Production goals
for a cow-calf operation include maintaining the cow as inexpensively as
possible while supporting good reproductive performance (timely conception,
birth of healthy calves) and good milk production that supports high calf
weaning weights. Lactating cows require more nutrients than pregnant,
non-lactating cows. In general, young cattle (stockers, calves, or replacement
heifers) require higher quality forage than mature cows, because they simply
cannot physically eat enough low quality forage to meet their nutritional needs
for acceptable rates of gain.
The species of forage grown and its method of harvest are major determinants
of yield and feed availability. Warm-season forages grow best during summer,
while cool-season forages grow best during spring and fall. Perennial forages
can provide dependable forage year after year, while annual forages may produce
large amounts of high-quality forage, but for relatively short periods of time.
Legumes are generally of higher nutritive quality than grasses and can
significantly improve the overall forage quality of a pasture if grown in a
mixture with grasses. In Arkansas, permanent pastures containing native or
improved perennial grasses or legumes are available nearly year-round, and are
commonly used in cow-calf operations, and sometimes with stockering (backgrounding).
Winter annual temporary pastures are used primarily for stockers, as creeps for
calves under fall calving systems, or sometimes for cows. Stockpiling of
cool-season grasses is used primarily with cow-calf operations. Green-chop
(mechanical harvest and immediate feeding of green forages) is sometimes used in
stocker operations. Silage is not often used by Arkansas beef producers, but can
have a place in stocker or finishing programs. Hay is used in all types of beef
cattle operations.
Grazing Management Systems
Grazing systems offer cattlemen flexible management options for producing and
utilizing forage crops efficiently. Grazing requires less machinery, labor,
facilities, and expense than the feeding of stored forages. Cattle can harvest
forage with minimal help, but for best productivity, the producer must actively
manage the pastures. The quantity of forage available and its quality may vary
greatly according to forage species, season of the year, weather fluctuations,
and grazing management.
Temperature, soil moisture, and fertility are the major factors influencing
rate of plant growth and forage quality. Warm-season species like bermudagrass,
bahiagrass, dallisgrass, and sorghum-sudangrass grow best during the late
spring, summer, and early fall months, and go dormant in the winter. Cool-season
forage species like tall fescue, orchardgrass, clovers, ryegrass, and small
grains grow best in fall and spring and make little if any growth during summer
or the coldest part of winter. In general, a combination of one-third to
one-half warm-season forage and one-half to two-thirds cool-season forages on
northern Arkansas farms will provide the longest grazing season, while southern
Arkansas farms should have a ratio of about one-third cool-season forages to
two-thirds warm-season forages.
Warm-season grasses generally have lower forage quality than cool-season
forages. The quality difference is in part due to biology of the plants, and in
part because warm growing temperatures and long days increase the fiber content
of all forages. All forage species grow best when soil moisture is not limiting
(either too little or too much), but some species will tolerate drought or poor
drainage better than others. Therefore, when new pastures are established on
sites with particular problems, careful attention should be paid to insuring a
compatible match between the site and the new forage. Applications of fertilizer
that are appropriate according to soil test, forage species, and desired level
of productivity will enhance yields and can be used to help even out forage
supply over the year.
Several aspects of plant physiology and response to defoliation must be
understood to manage pastures wisely. The plant leaf is responsible for
conducting photosynthesis and exporting nutrients to the crown or root for
storage. As such, the leaf is vital to the survival of the plant, but it is also
the location of the most nutrients for the grazing animal. If all leaves are
removed from the plant, regrowth must be fueled by the stored energy in the
crown or roots, which is a relatively slow process. The longer the interval
between defoliations for most forages, the more energy the plant can store, and
the easier it is to maintain rapid regrowth and stand persistence over the
years. Frequent total defoliation will eventually kill most plants. However,
because forage plants lose quality rapidly once they begin to flower, the longer
the defoliation interval, the lower the forage quality. Lower forage quality
will decrease forage intake by cattle, digestibility, and animal performance.
Low forage quality also decreases palatability, so animals may not consume all
the available forage. Forage species that keep some leaves very close to the
ground (like bermudagrass, dallisgrass, tall fescue, and white clover) can
tolerate more frequent and closer grazing than can taller forages (like
bluestems, johnsongrass, and alfalfa) because animals never get all the leaves.
Choosing the stocking rate of cattle is another compromise decision. Stocking
rate refers to the number of cattle carried on the total acres of pasture on the
farm. It should not be confused with stocking density, a term used with
rotational grazing systems to describe the number of animals per unit pasture
area per day of grazing. Highest rates of gain per animal are obtained on low
stocking rates, while highest gain per acre may be realized at high stocking
rates with low gains on individual animals. Under practical conditions, the most
economical stocking rate is usually just above the level that gives best
individual animal performance, and will provide good rates of gain with minimal
wastage of forage. Since forage yield and quality is changing over the growing
season, the optimal stocking rate will also change over time. Producers can
compensate for changing forage availability by adding or subtracting animals
from a given pasture area, or by changing the area of pasture available to a set
number of animals.
Permanent Pastures
Permanent pastures contain mostly perennial grass or legume species that are
expected to persist and be productive for many years. These are often found on
land that is not suitable for cultivation. Most permanent pastures in Arkansas
consist of bermudagrass or tall fescue, with some acreage in bahiagrass,
dallisgrass, smooth bromegrass, or orchardgrass. White and red clovers are the
most commonly used perennial legumes.
Temporary Pastures
Temporary pastures usually consist of annual forage crops that are grown to
provide a specific period of grazing during a time of year when perennial forage
is in short supply. Temporary pastures may be produced on prepared cropland.
However, most are produced by sod-seeding annual species into perennial grass
stands, especially into dormant bermudagrass. The most common temporary pastures
in Arkansas are wheat, rye, oats, and/or annual ryegrass, which are utilized
during the winter. Newly available bromegrasses, such as Matua, behave as
reseeding annuals in Arkansas, and can be used for temporary cool-season
pasture. Annual legumes are often added to annual grass mixtures to add protein.
Forage crops in the brassica family include turnips, forage rape, and kale, and
can provide excellent fall and winter grazing. In summer, sudangrass,
sorghum-sudangrass, and pearl millet can be used to provide temporary pasture.
Most temporary pasture species have some capacity for regrowth if grazed
carefully while in the vegetative stage, but once flowering is initiated, they
quickly mature and die.
Continuous Grazing
Continuous grazing is the practice of letting animals have unlimited access
to the entire pasture area all of the time. Depending on forage species, soil
type, and fertilizer, stocking rates from 1 to 6 acres per cow-calf unit are
used. Its main advantage is a low requirement for management time and labor.
However, it can be a rather inefficient way to utilize forages. Selection of the
right stocking rate is the primary challenge. If the pasture is continually
overstocked, animals will not get enough to eat and will perform poorly,
preferred forage species may be eliminated from the pasture, and water and soil
conservation is affected. If the pasture is always understocked, individual
animals may gain very well because they are able to select only the best quality
forage to eat, but large amounts of forage growth will be wasted, and weeds tend
to become a problem. If an intermediate stocking rate is used, the pasture will
often be undergrazed during times of rapid forage growth and overgrazed when
forage growth is slow.
These problems can be addressed by adding a bit more management to the
continuous grazing system. The producer can adjust stocking rates periodically
to better match current forage availability. The pasture can be clipped
periodically to remove tall, mature, unpalatable forage and weeds. A temporary
fence can be used to exclude animals from part of the pasture when forage is
growing too fast for animals to keep up, and hay can be harvested from the
excluded area for use during slow pasture growth periods.
Short, rhizomatous forage species that form dense sods are more tolerant of
frequent close grazing and are preferred for continuous grazing systems over
taller, bunch-forming plants. Common bermudagrass and white clover are two of
the best adapted forages for continuous grazing, and should be stocked to
maintain a 3 to 5-inch sward height. Evidence from southern Arkansas suggests
that bermudagrass may be easier to manage under continuous grazing than under
rotational systems because it maintains much better forage quality under
frequent grazing.
Rotational Grazing
Rotational grazing is the practice of dividing the pasture area into smaller
sections (sometimes called paddocks) and then moving the animals from one
paddock to another. In this system, forages are grazed when they are at their
optimum compromise of yield and quality and then rested to accumulate regrowth.
Animals are usually stocked more heavily in paddocks than in continuous grazing
systems. When done correctly this results both in more even grazing (eliminating
the need for clipping) and in animals utilizing a greater percentage of the
available forage. Typically, hay can be harvested from some of the paddocks
during peak growth periods. Availability of relatively low cost electric fencing
makes division of large areas into paddocks more affordable, but rotational
grazing can also be employed using permanent fences. Potential advantages of
rotational grazing over continuous grazing are:
1. improved persistence of desirable forage species as a result of adequate
rest periods to recover from grazing and replenish root reserves
2. less forage waste
3. better control of weeds
4. more grazing days per acre (requiring less hay feeding)
5. more even return of manure and urine to the pasture
6. more frequent observation of animals
7. usually a greater total gain per acre.
However, rotational grazing requires more management expertise, time, and a
greater investment in fencing and water supplies for the paddock system. Because
animals are forced to eat all the forage, they cannot select a high quality diet
and often do not gain as much individually as on a continuous grazing system.
Rotational grazing systems can be very simple or very complex. The simplest
systems may consist of as few as three relatively large paddocks with animals
rotated every week to 10 days, while complex systems may contain 40 or more
small paddocks with animals moved every day. The number and size of paddocks
needed will be affected by herd size, class of animals, land available for
pasture, forage species, available labor, and production goals. In general, the
more paddocks used, the higher the forage quality that can be maintained in
them. This occurs because animals can be rotated through the paddocks quickly,
always using the one nearest to peak quality. If forage is growing too fast for
the livestock to keep up with it, forage in the most mature paddocks can be
harvested as hay. The length of the rest or regrowth period is the key to
keeping the forages growing well. Most pasture plants will require at least a
30-day regrowth period even at peak growth rates, and may require up to 6 weeks
to recover from grazing during stressful growing conditions. If there are not
enough paddocks to allow this length of rest, plants eventually become depleted
of energy, fail to regrow adequately, and the producer may run out of pasture
and need to feed hay. Many desirable forage species are very difficult to keep
in a pasture under anything other than a rotational system. This includes most
of the native and introduced bunchgrasses (switchgrass, Johnsongrass, big
bluestem, indiangrass, eastern gamagrass, old world bluestem, and orchardgrass)
and some legumes (alfalfa, sericea lespedeza).
Forward grazing is a variation of rotational grazing in which animals are
divided into groups depending on nutritional needs. First access to the paddocks
is given to the group with highest nutritional needs and potential for gain,
such as bred replacement heifers or stockers. They are allowed to select the
best quality forage from the paddock, and then they are moved to a second fresh
paddock before the first one is completely grazed down. The lower need group,
such as cows, is then put into the first paddock to finish grazing it down to
the desired stubble height.
Creep Grazing
Creep grazing is a system in which a high quality and a lower quality pasture
are side by side. A creep gate allows unweaned calves access to the high-quality
pasture while excluding the cows, thus in effect giving the calves a supplement
to milk. Versions of creep grazing can be employed in both continuous and
rotational systems.
Limit Grazing
In this system, animals are kept on a low quality pasture or dry lot for most
of the day, but are allowed access to a high quality pasture (often a temporary
or stockpiled pasture) for a few hours per day. This is most often used for
dairy cattle, but can be used to supplement frosted warm-season grass pastures
for beef cattle. The daily protein requirement of the cattle being fed is often
used to determine grazing time on the high quality (high protein) pasture. Other
nutrients are supplied by supplementary feeds (hay, silage, or grain). This
system can make good use of a limited supply of high quality pasture.
Strip Grazing
In a strip grazing system, animals are only allowed access to enough forage
to provide feed for a few days. This system is similar to rotational grazing in
that stocking density (in this case controlled by the amount of pasture made
available to the animals) is high enough that the cattle will consume most of
the available forage during the occupation period, thus decreasing waste but
also decreasing the overall nutritive quality of the diet. Access is controlled
using temporary electric fencing that is easy to move across the pasture. Strip
grazing is most often used with annual, temporary, or stockpiled forages where
immediate regrowth is not anticipated. If used on actively growing perennial
pastures where regrowth is desired, a backfence should be used to prevent
animals from returning to areas already grazed, where they will remove the early
regrowth and can damage the stand.
Stockpiling
Stockpiling is the practice of allowing forage to accumulate during late
summer and fall for grazing during winter and is also referred to as deferred
grazing. Tall fescue is the most commonly stockpiled forage in Arkansas because
it produces large amounts of leaves late in the season and holds its forage
quality extremely well in cold weather. Fescue can be set aside and stockpiled
anytime from August to November. The longer the set-aside period, the more
growth will be accumulated. However, stockpiling summer growth of fescue is not
recommended because it will contain a higher concentration of toxic fescue
endophyte than growth accumulated during cool weather. Growth made in the fall
will usually be of higher forage quality than summer growth (because of cooler
temperatures) and fall growth can be encouraged by fall fertilization.
Stockpiled pastures containing a mix of mature summer growth and fall vegetative
growth is suitable for dry, pregnant cows during winter, while forage stockpiled
during fall is suitable for lactating cows or stockers. Strip grazing makes for
the most efficient use of stockpiled tall fescue, because the forage loses
quality rapidly once the canopy is opened up to the weather by the action of
grazing and traffic.
Stored Forage
Hay
Hay is the most versatile form of stored feed. It can be made from almost any
pasture forage, can be fed to any class of cattle, and is relatively easy to
store and handle with a minimum of machinery and buildings compared to other
stored feeds. It fits well within a forage management program that includes
grazing because most grazing systems can be structured to allow storage of
temporary excesses of growth as hay. Hay can also be produced from specialized
fields intended solely as hay meadows, which allows the possibility of growing
high-yielding forage species or varieties than are better suited for hay than
pasture, such as hybrid bermudagrasses. Hay is more easily transported than
other stored forages and can be sold as a cash crop to supplement income from
the beef operation.
High quality hay is green, leafy, pleasant smelling, high in protein, low in
fiber, digestible, palatable, and free of foreign material, weeds, mold, and
toxic compounds. Stage of growth at harvest, weather at harvest, fertilizer
application, and storage method all influence hay quality. Just as with pasture,
forages yield more hay when harvested at mature stages, but forage quality will
be lower. Weather can make it difficult to put up hay of optimum quality. Poor
drying conditions or rain damage significantly decrease hay quality, and wet
soils may make it impossible to get on fields for timely harvests. Forage
testing is a vital aspect of identifying forage quality of hays, and can be
obtained through the University of Arkansas Diagnostic Laboratory or numerous
private labs. Book values for forage quality of different kinds of hay are
available and can be used in emergencies. However, these values are averages
based on a wide range of samples, and may not be accurate reflections of the
quality of specific hay on the farm. Just as with pastures, the highest quality
hays should be fed to the animals with the highest nutritional needs.
Storage facilities and type of hay package are keys to insuring that the hay
maintains the same forage quality that it had when first made. Hay can be made
in small or large rectangular bales, large round bales, or loose stacks.
Shortages of labor have made large hay bales attractive as they can be made and
handled with a minimum of labor. Large round bales are the most commonly seen
form of hay package in Arkansas. Round bales should be stored in a pole barn or
building if one is available because protection from weather prevents spoilage
of forage in the outside layers. In particular, high-value hays (legumes) or
loosely-made bales are best stored inside as they are most susceptible to loss
in value due to weathering. Tightly-made round bales will shed water to a degree
and can be stored outside. However, when hay is stored outside, there will a
loss of quality due to weathering and mold in the outer layers, and this can
spoil 5 to 30 percent of the forage in the bale. Losses can be reduced to the
low end of this range by getting bales off the ground on pallets, old tires, or
a gravel pad in a sunny location, leaving enough room between bales for good air
circulation, or by covering bales with plastic. Square bales do not shed water
and must be stored inside or under plastic if outside.
Losses are to be expected whenever hay is moved or fed, and include damage by
cattle such as trampling and manure contamination. Cattle may consume more hay
than they need or refuse to eat some parts of the bale. Once the bale is opened,
it is susceptible to weather damage if not consumed quickly, and fragile leaves
may shatter. The total loss can be up to 60 percent of the hay when cattle are
allowed free access to bales or stacks. Using recommended hay feeding methods
can reduce these losses, but labor requirements will be increased. Feeding hay
in some kind of bunk or rack reduces losses caused by cattle walking on the
forage. Hay rings are a convenient method of restricting access to large round
bales. Electric fences can be used to restrict animal access to stacks or bales.
Offering a one-day supply of hay at a time reduces waste. This can be
accomplished by unrolling large round bales. When possible, the site where hay
is fed should be rotated around within pastures, because high animal traffic
will quickly destroy the sod around a permanent feeding site. The resulting
muddy patch will increase trampling losses of hay. Also, periodically feeding
hay on areas of the pastures with low soil fertility will improve fertility by
returning manure to those areas. However, if a permanent hay feeding site is
chosen for convenience or ease of access, a concrete or gravel pad will help
prevent a muddy patch from developing.
Silage
Silage is the product of fermentation of high-moisture forages. It is an
acidic preserved product that is stable as long as it is maintained in an
airless environment. Silage exposed to air rapidly heats and spoils, so it must
be fed in one-day supplies. Silage requires more labor and equipment to feed
than hay, and is difficult to sell off the farm. However, it usually has lower
field and storage losses than hay. High energy forage crops like corn, small
grains, and sorghum are best suited for silage production, but good silage can
be made from relatively low-energy grass crops if a small amount of grain is
added at ensiling to help support the fermentation.
Traditionally, silage was made in relatively expensive permanent upright or
bunker structures that required more equipment and facilities for unloading and
feeding out than hay. These structures were rarely used by beef producers.
However, current technology has shown that silage can be made in large plastic
bags or by encasing high-moisture round bales with plastic. Round bale silage
can be harvested, handled, and fed in much the same way as hay. To save labor,
silage can be fed directly from bunkers, trenches, or stacks by allowing cattle
access to a limited area so that they do not expose more silage to air than they
can eat in a day.
Green-Chop
Green-chop is fresh forage that is harvested mechanically and then
transported to the cattle for immediate feeding. It can be a useful method of
feeding for confined cattle or when a limited amount of fresh forage is
available.
Supplementation
Feeding of supplements can sometimes improve the performance of pastured
cattle. Even high-quality forage may be deficient in some nutrients, and it is
sometimes necessary to feed cattle forages with less than optimum quality.
Forage quality of any lot of hay is variable and cannot be accurately determined
from average quality values given in books of feeding tables. Accurate
laboratory forage testing is vital to knowing exactly which nutrients are
deficient so that appropriate and cost-effective supplements can be chosen to
meet the nutrient needs of the class of cattle being fed. Forage is often
lacking in one or more minerals. These can be supplied easily in solid blocks or
loose mineral feeders. Stocker cattle on pasture may gain more weight when fed
small amounts (about 0.5 percent of their body weight per day) of a high-energy
supplement such as corn. Feeding greater amounts of energy supplements is
counterproductive because forage intake can be reduced. Energy supplements may
also be beneficial for nursing cows eating mature, low quality pasture or hay.
When forages are low in protein, cattle with high nutritional needs may benefit
from receiving about one pound per day of a protein supplement such as soybean
meal. By-product feeds such as corn gluten feed or soybean hulls can provide
economical sources of energy and protein when locally available. Premixed
energy/mineral, protein/mineral, and energy/protein/mineral supplements can be
purchased from many suppliers. Cost of these should always be carefully
considered against the expected benefits and the cost of buying the ingredients
separately.
For more information about forage management, contact your county Extension
office or refer to one of our
publications.
Back
to Forage Management Guides
|
