UNP-0007 GRAZING SYSTEMS
UNP-0007, New April 1999. Julio
E. Correa, Extension Animal Scientist, Associate Professor, Soil, Plant and Animal Sciences,
Alabama A&M University
Grazing Systems |
Ruminants, such as cattle, sheep, and goats, can digest
cellulosic substances and can convert plants to products such
as milk, meat, wool, and mohair. Pastureland, therefore, is critical
to the production of these ruminants and the products they provide.
In order to obtain maximum profits from pasture grazing, producers
must manage the land for high production per acre and must manage
the animals to minimize forage waste and to ensure that they are
growing sufficiently.
Grazing systems provide high-quality forage and reduce feed
and veterinary costs while avoiding manure buildup. Feed costs
are reduced because farmers and ranchers do not have to grow or
purchase forage and grain year-round, and veterinary costs are
reduced because animals on pasture have fewer health problems
than those that feed in the barnyard. In addition, pastures require
few or no pesticides and allow natural recycling of manure. They
also provide a continuous soil cover, thus protecting wildlife
habitats and important ecosystems.
The three most widely used grazing systems are continuous grazing,
intensive rotational grazing, and multispecies grazing.
Continuous Grazing
The primary grazing system used in Alabama, as in many other
states, is continuous grazing. In this grazing system, animals
graze a specific pasture area freely and uninterruptedly throughout
the year or grazing season. Because continuous grazing allows
animals to graze selectively, individual animal performance is
usually maximal. However, due to the selective grazing nature
of animals, some forages are overgrazed while less desirable plants
are undergrazed, which damages or wastes pastureland.
Intensive Rotational Grazing
The grazing system that most effectively uses pastureland is
the intensive rotational grazing system, which includes short-duration
grazing, rapid grazing, cell grazing, and strip grazing. In a
rotational grazing system, the pasture is fenced off into subdivisions
or paddocks, and animals are rotated according to the forage available
and the forage growth rate (Figure 1). Short grazing periods are
beneficial because they can increase the carrying capacity of
the pasture without plants being damaged. However, research indicates
that individual animal weight gains are higher under a continuous
grazing system than under an intensive rotational grazing system.
Intensive rotational grazing focuses more on animal production
per acre than on individual animal performance.
Figure 1.Intensive
rotational grazing allows for efficient use of pastures. |
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![](Images/Fig1.jpg) |
Additional advantages of intensive rotational grazing are that
animals can be examined more easily and frequently and that surplus
forage can be harvested as hay. In a sheep-grazing study conducted
at Alabama A&M University, 1,375 pounds of tall fescue hay
and 4,015 pounds of bermudagrass hay were produced on 0.6 acre
each (Mayoral, 1992). In another sheep-grazing study, more than
one-third of the rotational paddocks were consistently left ungrazed,
indicating the possibility for either higher stocking rates or
for hay production (Dorsey,1998). The advantages of hay production
under an intensive rotational grazing system become an economic
consideration when deciding which grazing system to use.
One other aspect that must be considered when choosing which
type of grazing system to use is the fact that a rotational grazing
system requires much more fencing than the other systems do. Rotational
grazing is more labor intensive and often more expensive than
traditional continuous grazing; however, the introduction of electric-powered
fences that are easy and quick to build has made subdividing pastures
easier and more economical. In 1993, the market for farm and ranch
fences in the U.S. was estimated to be $750 million per year,
with electrical fences comprising 10 percent of that (Leidner,
1993). Livestock producers have been using high-tensile electric
wire fencing, either permanent or temporary, for over a decade.
Electrical fences became popular as a way to exclude both domestic
and predatory animals and are also commonly used to prevent livestock
from grazing certain areas, such as pasture sprayed with herbicides.
Electroplastic twine is another development that may make it
easier and more economical for ruminant producers to establish
and improve intensive rotational grazing. This twine is particularly
useful with small ruminants in cell or strip grazing systems where
portable fencing is used. Electroplastic twine consists of six
stainless steel filaments woven into a bright orange polyethylene
twine for positive shocking and high visibility. The twine has
built-in UV-resistant properties for long life.
A portable fencing system consists mainly of the following
features:
- Portable reel - heavy-duty reel with self-insulated
spool and crank handle that operates like a ratchet to apply
tension to the fence
- Portable reel handle - mounting handle balanced for
carrying and rewinding, with a hook for hanging it on a wire
fence or tying it to a post
- Electrical wire - 660- and 1,650-foot bobbins of electroplastic
twine that can be easily rewound on portable reels
- Posts - any kind of material (wood, metal, fiberglass,
or fiberrod) can be used. Posts 3/8 inch in diameter or larger are easy to put
up and take down.
- Insulator - the kind used depends mostly on how to
best attach the wire to the post. Fiberglass and fiberrod posts
do not require insulators because they do not conduct electricity,
but wood and metal posts do require insulators. A rod-post insulator
for attaching electroplastic twine to posts 3/8 inch in diameter
is a must for portable fencing.
- Energizer - the kind used depends on the amount of
wire to be electrified, the source of power, the amount of vegetation
around the fence, and the type of animal to be contained. Battery-powered
energizers operate with or without solar panel recharging (Figure
2), and AC-powered energizers will charge various distances of
wire and maintain various voltages on fence lines subject to
heavy loads of grass, weeds, brush, etc.
Figure 2.
Battery-powered energizer |
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![](Images/Fig2.jpg) |
Properly managed, constructed, and serviced electrical fences
can increase the efficiency and profitability of cattle, sheep,
or goat enterprises through better management of animals and forage
resources. Since an electrical fence serves as both a mental and
physical barrier, much less material is needed to build it than
is needed to build a conventional fence. Therefore, electrical
fences can usually be erected for about half the cost of conventional
fences. In grazing demonstrations held in northern Alabama, sheep
were contained by fences having only two or three strands of electroplastic
twine.
Multispecies Grazing
Multispecies grazing is a grazing system in which cattle and
sheep graze together (Figure 3). Studies in the1950s and 1960s
showed that cattle, sheep, and goats do well together on shared
range because they have different grazing behaviors. Cattle mainly
eat grasses, and sheep and goats prefer broad-leafed plants such
as forbs and leaves from some small shrubs (Anderson and Havstad,
1991). Certain species of animals also graze differently because
of their mouth size, lip anatomy, and method of prehension (Matches,
1992). Sheep and goats have a partially lifted upper lip that
is very mobile and permits closer defoliation. Cattle have a fixed
upper lip that is relatively immobile (Church, 1979).
![](Images/Fig3.GIF)
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Figure 3. Multispecies grazing maximizes forage utilization. |
Multispecies grazing offers producers the opportunity for complementary
pasture use since what one species will not eat, the other will.
This significantly maximizes forage utilization, which translates
into higher animal production rates per acre, lower costs of production,
and better returns for farmers and ranchers. In addition, the
cattle's presence protects the sheep and goats from coyotes and
wild dogs.
Parasite Control in Grazing Systems
Although intensive and multispecies grazing systems offer many
benefits, animals within these systems, especially small ruminants,
are very vulnerable to internal parasite infection. Of most concern
is the barberpole worm, Haemonchus contortus, which feeds
on the host animal's blood with a voracious appetite (Figure 4).
This parasitic nematode is among the world's most widespread stomach
parasite of cattle, sheep, and goats. Producers who use grazing
systems must, therefore, develop preventive treatments and control
programs to combat this parasite and others.
![](Images/Fig4.jpg)
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Figure 4. Barberpole worm |
The following are some prevention and control practices for
treating grazing ruminants for internal parasites.
- Give cattle a deworming treatment about twice a year. A continuous
deworming product in block or mineral form can also be used as
a supplement to these treatments.
- Give nonresistant sheep a deworming treatment every 2 to
4 weeks during warm, wet weather conditions that favor parasite
development. Alternate between the types of dewormers used.
- Give pregnant ewes a deworming treatment about 2 weeks before
lambing. This will prevent contamination that results from the
rise in periparturient eggs.
- Give goats a similar deworming treatment as that given to
sheep, even though goats seem to be more tolerant to internal
parasites than sheep are.
- Take fecal egg counts before and after deworming to determine
the effectiveness of the dewormers.
- Follow the manufacturer's directions for all approved dewormers,
and consult your veterinarian if you have any questions or concerns.
Sheep producers may choose to raise sheep breeds that are resistant
to internal parasites (Correa et al,1998) (Figure 5). By doing
so, producers can reduce production costs while meeting consumers'
demands for animal products and pastures that are free of chemical
residues. For more information about the use of parasite-resistant
sheep, see Extension publication UNP-0006, "The Use of Sheep
Breeds Resistant to Internal Parasites."
Figure 5.
Sheep breeds such as the Florida Native are resistant to internal
parasites and therefore are well-suited for multispecies grazing. |
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![](Images/Fig5.jpg) |
Summary
Developing good grazing management programs can help ruminant
producers reduce the amount of purchased feeds they use and produce
the highest net income per grazing land unit. In Alabama, forages
are abundant almost year-round, and most improved pasture plants
grown in Alabama provide adequate nutrition for ruminants (Ball
et al, 1991). Although extreme environmental conditions may require
the supplemental use of hay, grain, protein, and minerals, the
economic outlook for cattle, sheep, and goat production from pastureland
appears to be excellent.
Sources
Anderson, D.M. and K.M. Havstad. 1991. As cited
by D. Senft and J. Corliss. 1991. Cattle and Sheep Together: Partners
in Grazing. Agricultural Research, ARS, USDA. December,
1991. pp.14.
Ball, D.M., D.S. Hoveland and G.D. Lacefield.
1991. Southern Forages. Potash and Phosphate Institute (PPI) Publishing
and The Foundation for Agronomic Research (FAR). Atlanta, GA.
Church, D.C. 1979. Digestive Physiology. In:
Digestive Physiology and Nutrition of Ruminants. Vol. 1
(2nd ed.), pp. 46. Oxford Press, Portland, OR.
Correa, J.E., J.G. Floyd, and L.A. Kriese-Anderson.
1998. Extension Publication UNP-0006, "The Use of Sheep Breeds
Resistant to Internal Parasites." Alabama Cooperative Extension
System, Alabama A&M and Auburn Universities.
Correa, J.E. 1993. "Intensive Rotational
Grazing of Sheep Using Electric Fences." Alabama A&M
University. Cooperative Extension Program. AGR-RD-A405.
Dorsey, J.Z.J. 1998. Production Performance
of Sheep under Rotational (Strip) Grazing Systems. Master's Thesis.
Alabama A&M University, Huntsville, Alabama.
Leidner, J. 1993. Fast Fencing. Progressive
Farmer: What's New in Electric Fencing. pp.24.
Matches, A.G. 1992. Plant Response To Grazing:
A Review. J. Prod. Agric. 5:1.
Mayoral, J.W. 1992. Production Performance
Of Sheep Under Rotational (Strip) Grazing Systems. Master's Thesis.
Alabama A&M University, Huntsville, Alabama.
For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information.
Issued in furtherance of Cooperative Extension work in agriculture and
home economics, Acts of May 8 and June 30, 1914, and other related
acts, in cooperation with the U.S. Department of Agriculture. The Alabama
Cooperative Extension System (Alabama A&M University and Auburn
University) offers educational programs, materials, and equal
opportunity employment to all people without regard to race, color,
national origin, religion, sex, age, veteran status, or disability.
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