Pasture, Rangeland, and Grazing Management

Abstract

Photo: Lee Rinehart, NCAT

In a time of high-cost inputs, pasture-based livestock production systems can naturally maintain soil and plant integrity while growing healthy ruminants. This publication profiles the general types of pasture and rangeland and offers information about management and expected yields. Weed management strategies are also discussed and tips are offered to rehabilitate depleted land. Issues in grazing management, such as paddock development, plant selection, drought, and plant toxicosis are also discussed. Resources and references are also presented.

Table of Contents

• Introduction
• Temperate Pasture
• Rangeland
• Managing Soil and Forage Resources
• Intake, Sward Density, and Grazing Period
• Legumes and Soil Fertility
• Stocking Rate
• Ecological Weed Management in Pastures
• Multi-Species Grazing
• Pasture Renovation and Establishment
• Rotational Grazing and Paddock Size
• Overgrazing
• Plant Species and Systems for Extending the Grazing Season
• Prescribed Grazing on Rangeland
• Managing for Drought
• Plant Toxicity
• Final Thoughts
• References
• Resources
• Further Resources

Introduction

Pasture is the basis of any livestock operation that purports to be truly sustainable. It is especially important as the livestock sector continues to experience extraordinarily high fuel and other input costs. Pasture-based production systems offer farmers and ranchers the ability to let the ruminants’ environment and immune system work together. An acceptable level of production can be attained as the ecological connections between ruminants, the soil, and the pasture plants is naturally maintained. Ruminants on pasture experience fewer health problems, due partially to reduced stress. Ruminants under confinement, on the other hand, are subject to high-grain rations that keep their digestive physiology running at top speed. Grain-fed ruminants typically require treatment for maladies such as acidosis, mastitis, and respiratory disease because their immune systems have become seriously compromised. A singular focus on productivity often causes more problems than a broader, systems approach. Given a well-conceived marketing plan, an up-to-date pasture-based operation can maintain reasonable production, reduce input costs, and achieve a positive economic return. Much of the livestock grazing land in the U.S. can be used more efficiently. For instance, USDA-Agricultural Research Service (ARS) scientists have conducted stocking rate tests on wheat pasture and old world bluestem perennial grass pastures, such as those that occupy large sections in the Southern Great Plains. The pastures were stocked with double the normal number of cattle using intensively-managed grazing techniques. Even in the arid West, increased stock density coupled with decreased time on a pasture has proven a successful strategy to increase livestock enterprise productivity while improving the condition of the rangeland.

The ecological processes that occur on temperate pastures are basically the same as those on arid rangelands. But the processes occur much slower on drier rangelands due mainly to temperature and moisture differences. The following section is a primer on the nature of both types of pasture ecology.

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Temperate Pasture

Temperate pastures are typically very productive. They are characterized by well-developed soils, medium to high precipitation, and moderate to rapid nutrient cycling. They can be dominated by warm or cool season plants, and occupy niches from Maine to Florida, from Texas to Minnesota, and from Southern California to the Pacific Northwest coastal regions of Washington and Oregon. Many irrigated riverine pastures in the intermountain and desert West also resemble temperate pastures due to deep soils, adequate moisture from irrigation or high water tables, and the presence of high-yielding plant species such as bromegrass and alfalfa. Temperate pastures will on average yield anywhere from 2,000 pounds of dry matter per acre per year to well over 12,000 pounds per acre, depending on plant species, soil type, growing season, grazing management, and other environmental factors.

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Rangeland

According to the Society for Range Management, rangelands contain natural vegetation dominated by grasses, forbs and shrubs and the land is managed as a natural ecosystem (SRM, No date). In North America, rangelands include the grasslands of the Great Plains stretching from Texas to Canada, from the prairie states of the Dakotas and Nebraska to the annual grasslands of California, and forestlands and wetlands throughout North America. Included in this definition are arid shrublands throughout the western United States, the arctic tundra and mountain meadows, and deserts throughout the southwest. Rangeland can also embrace pastures of introduced grasses, such as crested wheatgrass, that are managed as rangelands. Arid rangelands, which typify much of Arizona, New Mexico, Colorado, Wyoming, Utah, Nevada, Idaho, Montana, Oregon, California, and Washington, can yield anywhere from 200 to 1,500 pounds or more of dry matter per acre per year.

Rangelands are typically characterized by low precipitation, shallow soils, and slow nutrient cycling. They are usually dominated by grasses, forbs, and shrubs efficient at water and nutrient utilization. Consequently, practices appropriate to temperate pastures, such as fertilization and plowing, are often inappropriate on rangelands. Regardless, rangelands can be very productive, providing sustainable income for ranch communities while protecting valuable natural resources through appropriate grazing strategies. Specific strategies for sustainable rangeland management are covered below in the sections Prescribed Grazing and Developing a Grazing Management Plan on Rangeland.

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Managing Soil and Forage Resources

Fertile soil is the foundation of sustainable production. “Soil macro- and micro-organisms are the external digestive system that processes organic matter, delivering a smorgasbord of minerals, vitamins, and other nutrients to the crop at a metered pace. This is in contrast to the conventional approach where crops are flooded with a limited number of soluble fertilizer nutrients, leading to‘luxury consumption,’ imbalanced plant nutrition, and a susceptibility to disease and attack by insect pests” (NCAT, 2004).

Pasture systems are maintained through grazing and animal impact on the land, which accomplish the following:

• nutrient cycling through feces and urine
• timely defoliation and removal of plant material that encourages regrowth
• root death through leaf removal, which results in accumulation of underground organic matter and nutrient cycling
• increased water holding capacity through accumulation of organic matter in the soil
• hoof action, which breaks compacted soil near the surface, thereby allowing greater germination of seeds and encouraging regeneration of pasture swards.

Livestock should be turned onto cool-season grass pastures (orchardgrass, wheatgrasses, timothy, fescues, etc.) when the grass is 8 to 12 inches tall, and removed when the stubble height is 3 to 4 inches tall. Cool-season grasses have the ability to regrow relatively quickly after grazing, given proper conditions and soil moisture. Cool-season grasses can regrow through tillering (new shoot growth from the crown) or by sprouting new plants by way of underground rhizomes, depending on the species.

Native warm-season grasses (big bluestem, switchgrass, Indiangrass) should not be grazed too short, as heavy defoliation can seriously reduce its ability to persist over time. Native warm-season grasses just will not withstand the kind of defoliation that cool-season grasses can without causing harm to the pasture. It is also advisable to leave 6 to 8 inches of stubble after grazing (during the growing season) for native warm-season grasses. The extra leaf area is needed to photosynthesize plant sugars and prepare for later winter dormancy. A grazing system that leaves a 12-inch stubble at frost is appropriate for these grasses (Conservation Commission of the State of Missouri, 1984).

Graze warm-season annual grasses such as sorghum-sudan just before heading, when the plants are two feet tall. Livestock should be removed when these grasses are reduced to 4 to 6 inches of stubble. Take care when grazing sorghum-sudan and related grasses, as prussic acid poisoning can be a problem if grazed too early. See the section on Plant Toxicity below for more detailed information.

Grazing can begin when grass is shorter on warm-season bermudagrass, bahaigrass, and buffalograss pastures because these grasses have a more prostrate growing pattern and can generally handle heavier defoliation. Two to three inches of stubble on these grasses is not too short.

Cool season grass yields range from 4 to 6.5 tons per acre, and warm season pastures can typically yield from 2.5 to 5 tons per acre. In addition, pastures with grasses and legumes grown together typically yield 10 to 15 percent more forage than monoculture pastures. Producers should determine the annual pasture productivity, as this will provide a baseline of information with which to make management decisions.

Determining Forage Yield

Photo: Lee Rinehart, NCAT.

Forage yield can be practically determined by either (1) a pasture ruler or (2) a rising plate meter. (A more scientific, but more difficult measure, involves clipping a sample plot, drying the vegetation, and weighing the dry matter. It is known as clip-and-weigh and is discussed further in the box below). A pasture ruler is just that: a ruler calibrated in inches is placed on end at ground level, with forage height measured in inches. A rising plate meter measures density as well as height. A 20 X 20-inch plate weighing 2.6 pounds is dropped on a rule from waist height. For this measure in Iowa and Missouri, each inch of forage height equals 263 lb/ac DM (pounds per acre of dry matter), and has been verified by numerous clip-and-weigh field studies. This measure should be calibrated for local conditions by clip-and-weigh method to obtain accuracy.

A good rough estimate is 300 pounds of dry matter per acre per inch on a ruler. Jim Gerrish's values range from 150 pounds per acre per inch in a fair stand to 600 pounds per acre per inch in an excellent stand as determined by clipping and weighing numerous quadrants and comparing them to sward heights (Gerrish, 2004). The vast differences in the above estimates reflect differences in pasture types. For example, bermudagrass will most likely be different from bromegrass when measuring stand density with a ruler or rising plate meter. Consideration must be given to forage quality and the species of livestock grazing the pasture. The higher the forage quality (vegetative, growing grass, and clover), the greater the intake. For information on animal intake by species, please refer to the chart below. Understanding how much an animal will eat each day can assist producers in estimating forage demand.

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Intake, Sward Density, and Grazing Period

Forage intake is directly related to the density of the pasture sward. Ruminants can take only a limited number of bites per minute while grazing, and cattle in particular will only graze for about eight hours per day. It is important then to ensure that each bite taken by the grazing animal is the largest bite she can get. Cattle graze by wrapping their tongue around and ripping up forage. Large bites of forage are therefore ensured by maintaining dense pastures.

Dense pastures are pastures with actively growing and tillering forage plants. Tillering occurs in grasses that are grazed or mowed while vegetative, which results in the activation of basal growing points and the initiation and growth of new stems and leaves. Tillering results in a plant covering more basal area, therefore helping to make a pasture denser.

The length of the grazing period (time in a paddock) also has a direct effect on pasture intake. An animal’s intake decreases the longer it remains in a given paddock. This is due to (1) the effect of plant disappearance (as plants are grazed) and subsequent searching by cattle for the next bite, and (2) the decrease in crude protein content beginning roughly two days after the animals have been turned in to the paddock. Jim Gerrish has shown that as an animal remains in a paddock, intake and liveweight gains decrease. (Gerrish, 2004) It is for this reason that most dairy graziers move high-producing animals to new paddocks after each milking.

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Legumes and Soil Fertility

Legumes like clover, alfalfa, birdsfoot trefoil, sainfoin, and vetch have the ability to convert atmospheric nitrogen to the plant-available form of nitrogen through the symbiotic work of rhizobium bacteria, which occur naturally in a healthy soil. “Nitrogen fixation by legumes can be in the range of 25-75 pounds of nitrogen per acre per year in a natural ecosystem, and several hundred pounds in a cropping system.” (Lindemann and Glover, 2003) For well-managed diverse pastures, supplemental nitrogen fertilization can be eliminated altogether. For pastures under high density grazing systems, 70 to 85 percent of the nitrogen taken in by the animals is returned and cycled back to the soil in the form of feces and urine. Thus a diverse pasture with a significant legume component, which is managed intensively with heavy stocking and frequent moves, has the potential to become a stable, closed system.

Stocking Rate

Determining the initial stocking rate for a given pasture is relatively simple, but not necessarily easy. It is simple because the calculations are relatively straightforward. It is not easy because you familiarize yourself with basic forage growth principles and apply those principles to what you observe on your own pasture.

Several key issues must be considered to determine the optimal number of animals a pasture will support. Consideration must be given to forage production potential, utilization patterns by livestock, the nutrient content of the forage and forage growth patterns, the plant species that compose the pasture, species diversity of the pasture plant community, and seasonal variations in temperature and moisture.

A simplified method for determining the initial stocking rate for a pasture of known acreage is to (1) estimate average yield per acre (see Determining Forage Yield above), (2) determine average animal weight, and (3) estimate the length of the grazing season in days. These figures can be used to determine the number of animals that can be grazed in the pasture for the season by using the following formula:

Example: Determine number of 1,000 pound cows a 50-acre pasture will support for 100 days given 3,000 pounds of dry matter per acre…

= 37.5 or 37 cows

More information on stocking rate is addressed below in the section entitled Rotational Grazing and Paddock Size.

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Ecological Weed Management in Pastures

Agricultural systems are very complex biological systems that operate in a particular ecological balance. Each region of thecountry, indeed each watershed and field, might behave in very different ways because of differences in soil type and depth, indigenous or local plant cover, cropping systems, temperature, and water availability, not to mention field cropping history. By developing a cropping system or perennial pasture that utilizes nature’s own defenses and achieves ecological balance, a sustainable, pest-limited crop can be grown.

Do You Really Have a Weed Problem?

Many plants considered pasture weeds are highly palatable and nutritious during the vegetative stage. Take, for instance, dandelion and plantain. Both are numerous in many pastures, and producers can spend thousands of dollars spraying them with herbicides. They are, however, valuable plants that occupy different root zones, and so deliver nutrients from different soil depths. They are also very nutritious and palatable when young. These and many other “weeds” can be a valuable contribution to sustainable pastures. Even our so-called “noxious weeds,” like knapweed and kochia, can be grazed by sheep, goats, or cattle with skilled management.

Weeds are often a result of soil disturbance and human interference in nature. Weeds are plants that occupy spaces that humans do not want them to occupy, and farmers have many very good reasons for not wanting them to occupy certain spaces. Some are non-native, invasive plants with the capacity to crowd out or compromise the health of other plants and animals. Those types of weeds may need concerted control strategies. In agriculture we have become very accustomed to taking reactive measures—whether pesticide application or mechanical approaches like cultivation—in order to eliminate unwanted plants and establish a favorable environment for the kinds of plants we choose to be there. But if we can look at crop production and pasture as “systems,” and begin to understand how plants and animals and humans interact on a given landscape, weeds will become much less of a problem. By managing croplands and pastures according to natural principles we can significantly reduce weed problems. For more information see ATTRA’s Principles of Sustainable Weed Management for Croplands.

Techniques for Dealing with Problem Weeds in Pastures

Keeping weeds out of a pasture is much easier than trying to get rid of a bad infestation. Some management practices to consider for keeping pastures weed-free include:

• terminate low producing, weedy fields
• rotate perennial pastures with annuals
• integrate a high-density rotational grazing system
• know your pastures
• consider multi-species grazing

These methods, used alone or in combination, can easily be incorporated into a pasture management system, setting up a situation in which weeds find it hard to get ground. When pasture stands such as alfalfa get too old, they often begin to decline and allow other plants to take over. Many times the grass component of the field will increase as alfalfa decreases, but in instances of low fertility or drought, weeds can take advantage of the open niche and become established. Terminating and reseeding the field is sometimes recommended. Some producers refer to this as “farming” the pasture. For some pastures that are terminated, consider planting to winter wheat, or oats and winter peas for a season. These are in themselves valuable forage crops, and they help to break pest cycles while building soil all the while.

High density grazing systems also diminish weed invasion by reducing grazing selectivity. As an animal is forced to consume all the plants in a given area, no one plant is favored. This gives grass an advantage. Grass, because of the lowered position of its growing point when vegetative, tolerates leaf removal better than broadleaf plants, which often elevate their growing points much earlier in the season. Very intensive systems can even favor grass over legume growth, so pay careful attention to the legume component of intensively grazed paddocks. Reseed annual legumes by frost-seeding, feeding seed to cattle, broadcasting in the fall, or allowing legumes to go to seed to maintain legumes in these systems. See the section Pasture Renovation and Establishment for more information.

Most of all, know your pastures. Make it a point to understand the soil types and how they change with the aspect and slope of the land. Obtain some reference guides to assist in identifying the plants on your farm or ranch (the local Cooperative Extension Service is a great place to find these). The more you know about what your pastures will produce, the better position you will be in to make appropriate management decisions. Remember—the principle concern in managing unwanted pasture plants is to:

• encourage forage growth over weed growth through selection of appropriate livestock species and proper timing of grazing
• ensure adequate soil fertility through nutrient cycling, species diversity, and inclusion of legumes
• rotate non-erodible fields, especially monoculture perennial fields, to break weed cycles.

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Multi-Species Grazing

Multi-species grazing refers to the practice of utilizing different livestock species to:

• diversify farm income
• utilize pastures of different ecological types on the farm
• manipulate the plant community to meet the production goals of the farm
• interrupt parasite life cycles

Cattle, sheep, and goats evolved eating different plant types. Cattle typically consume, in order of preference, grasses, forbs, and shrubs; whereas sheep will consume forbs, grasses, and shrubs and goats will seek shrubs, forbs, and grasses.

Sheep have been effectively used on western native ranges to control invasive species such as spotted knapweed, leafy spurge, and yellow starthistle. Cattle grazing in conventional rotations often remain on western ranges for weeks at a time during the summer, and are moved when a set stubble height of key grass species like bluebunch wheatgrass or rough fescue is attained. When cattle, being primarily grass-eaters, remain in a pasture for long periods of time, they tend to exhibit grazing selectivity and choose vegetative grasses and young forbs over knapweed and other noxious weeds. Ranchers who have allowed bands of 800 or more sheep to graze for several days before or immediately after the cattle have seen significant knapweed usage by the sheep, with moderate grass utilization. Applying pressure with diversified livestock to knapweed, other forbs, and grasses in equal amounts will increase range biodiversity significantly over time. Sheep can be used as an alternative enterprise by taking value from wool, lambs, or by contract grazing on other parcels to control noxious weeds. Goats have a similar utility in areas with shrub infestation, and have been successfully used to control kudzu, English ivy, scotchbroom, Chinese tallowtree, juniper, and mesquite in many parts of the country.

Small ruminants can also add value to a farm by providing meat and milk products to growing ethnic groups that seek these traditional foods. Refer to the ATTRA publication Multispecies Grazing for more information.

Using small ruminants on cattle operations will necessitate a change in farm and ranch infrastructure. Fencing, lambing sheds, and secure paddocks in areas with predators (wolf, coyote, or bear country) are often necessary, but costs can add up and drain profitability.

Other methods of maintaining small ruminants on ranches are:

• employing a competent herder who will ensure the sheep or goats graze the necessary places, and
• running the animals with guard dogs, donkeys, or llamas as a predator deterrent

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Pasture Renovation and Establishment

When is it appropriate to renovate pastures? Most times renovation isn’t necessary. Many farmers and ranchers have noticed increased productivity and decreased weed problems merely by working out a high-density rotational grazing system. Pastures are very resilient and, when maintained in the vegetative stage for most of the grazing season, ecologically appropriate grasses and forbs often begin to dominate where weeds and other unpalatable plants once proliferated. This happens due to the ecological principle called succession (see box below).

Nature tends toward the stability that comes with species complexity. Complex pasture systems occupy all available space both above and below ground, and therefore utilize nutrients and water more efficiently. Complex Pasture systems are more resilient from year to year, as some species will thrive during wet times, and others will proliferate during drier times. Simple systems, on the other hand, are less resilient and are prone to disease and insect attack due to the absence of diversity. In simple systems, one or two species prevail, and there are fewer niches for beneficial organisms to occupy. Simple systems also exploit only a single soil layer, and therefore many soil nutrients will remain isolated from the system.

For those fields that have been cropped with annuals for the past several decades, renovation and reseeding might be appropriate, especially if high-yielding dairy cattle or growing lambs are to be grazing them. What follows is a short discussion on pasture establishment. For more information on field renovation and reseeding, including budgets for pasture establishment on a per-acre basis, see ATTRA’s Converting Cropland to Perennial Grassland.

Pasture Establishment

Photo: USDA NRCS.

Establishing a new pasture is a time-consuming and expensive process. Careful attention should be paid to proper plant material selection, soil tilth and seedbed preparation, soil fertility and the addition of compost or manures, green manure plow-down, and amendments with rock powders. Plant materials should be adapted to the native soil pH and water holding characteristics, annual precipitation, temperature, seasonality, and grazing system. Seed bed preparation is a good time to incorporate rock phosphate and adjust the soil pH by adding lime according to soil test recommendations.

Proper seedbed preparation is very important for establishing a productive pasture. There are essentially three ways to plant pasture grasses and legumes:

• planting into a prepared seedbed
• no-till planting into the stubble of a prior crop
• or interseeding into an existing stand.

Seed to soil contact is of extreme importance when planting by any method. The seed must remain in contact with moist soil for the first month after germination or the seedling will wither. There are various methods to achieve seed to soil contact while planting. Drilling with a grass drill is the most effective, as it allows for better control of seed placement. Many times packer wheels follow the drill to firm the seedbed and ensure seed to soil contact. Broadcast seeding can be effective for some species, especially if the soil is packed after planting. Pulling a roller or dragging a harrow behind a tractor or four-wheeler is an effective tool to increase the germination of broadcast plantings, especially for ryegrass and clover seeds. Other grass seeds such as timothy, orchardgrass, and most warm season native grasses do not establish well by broadcasting and should be drilled. Be careful not to plant too deep or the seeds might not germinate. Follow local Cooperative Extension recommendations on seeding rate and depth.

Another method of planting new pastures is frost seeding. Frost seeding works well in areas that experience a freeze-thaw pattern in the spring before green-up. Broadcast seeds after snowmelt and allow the natural freeze-thaw action that occurs each day to work the seed into the ground. If the timing is right, this can be an effective way to incorporate legumes into a grass pasture. For the humid areas of the south or drier areas of the west, fall-seeding of legumes is more appropriate so that they can get established during the winter rainy season.

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Rotational Grazing and Paddock Size

Photo: Linda Coffey, NCAT

If given a choice, livestock will only eat the highest quality, most palatable plants in a pasture. In order to ensure that plant biodiversity is maintained in the pasture, a grazing management system may need to be set up to better control livestock grazing. The grazing elements to control are timing and intensity of grazing. This means controlling the number of animals and length of time they remain in a pasture.

Rotational grazing systems take full advantage of the benefits of nutrient cycling as well as the ecological balance that comes from the relationships between pastures and grazing animals. High density stocking for short periods helps to build soil organic matter and develops highly productive, dense, resilient pastures. For more information see ATTRA’s Rotational Grazing and Paddock Design, Fencing, and Water Systems for Controlled Grazing.

A rotational grazing management plan need not be complex. The plan merely has to direct the grazing animals to eat when and where you want them to and to keep the plants in a growing (vegetative) stage. Rotational grazing allows for more effective forage utilization by increasing herd size on smaller paddocks for a shorter time, thereby decreasing grazing selectivity and giving the farmer more control on what and when the livestock eat. The basic principles of rotational grazing management include:

• proper timing of grazing (corresponding to plant physiological stage)
• proper intensity of grazing (duration on the pasture)
• residue or plant height after grazing
• duration of rest

Allow the pasture plants to get to sufficient height prior to turning the cattle onto the pasture. By waiting until the grass is 8 to 12 inches high, depending on species, the roots will have become well developed and the plants can handle defoliation. Grazing intensity, or duration, can be taken care of by designing a suitable rotational grazing system. Rotational grazing, as the name implies, involves moving the cattle periodically from pasture or paddock to paddock. For instance, a good rule of thumb is to split a pasture into 10 or more paddocks with electric wire or electric tape, and stock each paddock heavily for a short amount of time (see the accompanying box for determining the number of paddocks and paddock size). By doing this you are forcing the animals to eat all that’s there, including weedy plants they might otherwise not eat. However, before the animals eat the plants to the ground, you move them to the next paddock. This takes into account the third principle. It’s important to leave several inches of grass to allow adequate leaf area for subsequent regrowth.

Depending on the species, you will need to leave from 2 to 6 inches of plant stubble at moving time. An 11-paddock rotational grazing system that allows animals to graze each pasture for 3 days will give each paddock 30 days of rest (These figures are for planning purposes; it is recommended to move according to forage height rather than by the number of days on pasture).

Grasses need 15 to 50 days of rest between grazing events to allow adequate regrowth, depending on season, moisture, and plant type. The accompanying chart shows typical rest times for various pasture plants, realizing that water and moisture will have a large effect on plant regrowth.

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Overgrazing

Overgrazing occurs when the grazing pressure exceeds the carrying capacity of the pasture. This condition is not really a function of how many animals are on a pasture, but how long they remain there. In grazing management, time is the most important factor to consider in establishing a grazing system for sustained forage production. Continuous grazing allows livestock to selectively graze the most palatable plants over and over. The problem with this isn’t necessarily in the selective grazing activity, but in the fact that the grazed plant does not get the time to regrow before it is grazed again. New growth is more palatable and contains more nutrients than older growth, so animals will come back for a second and third bite as long as they are in the pasture, resulting in the most palatable forages being killed out.

Divide pastures into enough paddocks to ensure that all plants have ample time to regrow after grazing. In addition, for pastures with adequate water during the growing season, a very high stock density encourages animals to graze the pasture more uniformly than if the pasture was lightly stocked. In this situation the “weedy” species are being grazed at the same intensity as the “good” species.

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Plant Species and Systems for Extending the Grazing Season

Species used to extend the grazing season include cool season annual grasses such as ryegrass and cereal grains, forage brassicas like kale, rape, and turnips, warm-season annual grasses such as sorghum-sudan hybrids, pearl millet, and corn, and legumes like Austrian winter pea (cool-season) and forage soybeans (warm-season). These annual crops can be incorporated into a perennial pasture by several methods.

Annual ryegrass and cereal grains (oats, wheat, and rye) can be overseeded into warm-season pastures in the fall. These pastures will be ready to graze in December to January in the Deep South, and early spring for parts further north. Ryegrass establishes well when broadcast into perennial sod, but small grains typically establish better when drilled into sod. Brassicas can be spring or summer planted into corn or other annual crops to provide late summer or fall forage for livestock. These crops produce as much as 12,000 pounds per acre and are well suited to strip-grazing.

Warm-season annuals like pearl millet, corn, and sorghum-sudan are highly nutritious and provide quality forage during the summer when cool-season pastures (orchardgrass, fescue, and bromegrass) slow down. Summer annuals fit nicely in rotational grazing systems. Careful attention to drought-stressed plants is warranted as these are susceptible to excessive nitrate and/or prussic acid accumulation and subsequent livestock poisoning. Contact your local Cooperative Extension office for information on testing for these compounds.

Other species that can be used successfully to extend the grazing season are Austrian winter pea and forage soybeans. Winter pea, a cool-season legume, is often used as a cover crop in cereal rotations. Spring grazing of winter pea allows ranchers to rest more sensitive pastures and graze them when the soil is drier and the vegetation better established. Forage soybeans likewise have a place in summer cropping systems where farmers are rotating crops such as corn or grain sorghum with legumes to build soil organic matter. Grazing these crops for several months before plowing down the green plants is an added bonus to building soil organic matter and tilth.

Annual forage crops can be an excellent addition to a farm by extending the grazing season several weeks or even months. However, annual cropping systems often come with environmental costs such as erosion, loss of organic matter, and destruction of soil structure, most notably when soils are heavily tilled. Consider rotating annual crops to different fields each year to minimize environmental impacts such as water or wind erosion.

Stockpiling Forages

Stockpiling is defined as letting forage grow during summer and deferring grazing to the fall or winter. This is an effective way of providing winter forage in some areas and can reduce the need for harvested forage. If it reduces hay use at all, significant savings can be realized. This system works well for early winter when spring-calving cows are in mid-pregnancy. Stockpiled grazing can be followed with meadow feeding of high quality alfalfa hay prior to calving.

Stockpiling has been shown to work well given appropriate pasture management and efficient allocation of dormant pasture during the winter. Many grass species will maintain a relatively high nutrient content and palatability for several months after dormancy begins. Two extra months of grazing can significantly reduce the costs associated with producing and feeding hay. In some cases, producers have been able to utilize stockpiled forage and eliminate the need for hay feeding completely. This usually works better in climates where the dormant grass can be preserved longer under adequate snow cover, and/or because of reduced microbial decomposition caused by low temperatures and limited moisture.

Stockpiled forages can either be limit-fed (allowing only so many hours of grazing per day), or by strip-grazing with a movable electric wire or tape. Other options for feeding stockpiled forages are to swath them with a hay mower, and then rake them into windrows. Cattle can graze directly off the windrow during the winter by using an electric wire or tape to ration hay on a daily basis. This is similar to strip-grazing in that the wire is moved each day to expose a predetermined amount of forage for grazing. This method, while still relying on a tractor to cut and windrow the hay, reduces the amount of fuel, materials, and hay equipment needed for baling and feeding hay by eliminating the baling process altogether. This method works best in drier regions where weathering is less likely to reduce the nutritional quality and palatability of the hay.

For more information on grazing season extension call ATTRA at 800-346-9140.

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Prescribed Grazing on Rangeland

Prescribed grazing can be thought of as a process of developing a grazing system that seeks to integrate the economic and ecological realities that ranchers are faced with on the western range. “The controlled harvest of vegetation with grazing or browsing animals, managed with the intent to achieve a specified objective,” is referred to as prescribed grazing. (USDA, 1997) Management objectives addressed by prescribed grazing include:

• Improve or maintain the health and vigor of selected plant(s) and to maintain a stable and desired plant community
• Provide or maintain food, cover, and shelter for animals of concern
• Improve or maintain animal health and productivity
• Maintain or improve water quality and quantity
• Reduce accelerated soil erosion and maintain or improve soil condition for susceptibility of the resource (USDA, 1997)

A very crucial aspect of a prescribed grazing regime is the development of a workable and ecologically appropriate grazing management plan.

Developing a Grazing Management Plan on Rangeland

Designing an effective grazing plan isn’t as daunting as it seems. Mostly it entails applying observation to management, making further observations, and then making adjustments as needed. There are five steps in developing a grazing plan. They are:

1. Inventory
   
   
2. Define Goals
   
   
3. Determine Grazing Units
   
   
4. Develop a Grazing Schedule
   
   
5. Develop a Monitoring and Evaluation Plan (Montana DNRC, 1999)

Inventory

Appropriate decisions about land and pasture use entail gathering baseline information. Obtain soil maps from your NRCS office and mark appropriate land forms, soil types, fences and paddocks. Find out what plants are in each pasture, and evaluate the pastures based upon a condition score. Utilize features such as key species, percent canopy cover, amount of bare ground, presence of noxious weeds, annual forage production in pounds per acre, and amount of residue to determine pasture condition and productivity.

Define Goals

Make a list of what you want to accomplish. This will be a list of your expectations and will guide you in making plans and decisions. Do you want to improve the economic value of the ranch? Maintain wildlife habitat? Improve water quality and quantity? Reduce noxious weeds? Also consider available acreage and the amount of time you have to put into this project.

Determine Grazing Units

Divide the pastures into units that you can rotate animals through. This will allow you to rest pastures and allow for regrowth following grazing. It will also allow you to rotate grazing on a seasonal basis as well. Determine how much forage is available in each grazing unit and map it out. Note key species, percent cover, water availability, facilities, and other aspects important to you. Remember that livestock should always be within at most two hours walking distance from water. This will help you to determine grazing unit size (for large parcels).

Develop a Grazing Schedule

This will be a graphic illustration of your plans for grazing each unit during the grazing season. Develop the schedule based on your total Animal Units (AUs) and available Animal Unit Months (AUMs) in each unit. If you have a 100-acre pasture with 2 AUMs per acre, you have 200 animal unit months of forage available. At 50 percent allowable use, cut it in half to 100 AUMs. This means you have enough forage available to feed 100 animal units for one month. Or, said another way, 50 animal units for two months, 33 for three months, and so on. For more detailed information on calculating AUM’s see the Montana Grazingland Animal Unit Month (AUM) Estimator located at: www.mt.nrcs.usda.gov/technical/ecs/range/technotes/rangetechnoteMT32.html

Important concepts here are duration of grazing and time for regrowth. Some range ecologists and managers believe that grazing intensity is also important, and it is. A plant needs to have green leaves left after grazing for photosynthesis and subsequent regrowth. However, others feel that grazing severity isn’t as important as regrowth time. Whichever you choose, it is important to remember to allow plenty of time for adequate regrowth before the animal gets to bite a plant a second time. Take a look at the native plants on an upland range site if you have the opportunity. Some, like bluebunch wheatgrass and little bluestem, are large-statured and can handle several bites from an animal in one grazing event. Some, like Sandburg bluegrass, Idaho fescue, and black grama, are smaller, and one bite is all it takes to reduce the plant to stubble. Cattle, especially, tend to graze severely, so don’t get too caught up in how much they take off. Strive for 50 percent use, and allow for regrowth. For some sites on dry ranges, this will mean one grazing event per year. For areas with more moisture, you might be able to return every 15 to 30 days for another grazing event.

Monitoring

This is the most neglected part of range management, and the most important. A good monitoring system allows you to check how your management decisions are working on the ground. It will allow you to determine, for instance, if a particular grazing plan is having the desired effect over time. A monitoring plan will often involve a few important evaluation criteria, such as plant species composition, percent cover, and frequency of species. By comparing these measurements over time, you can start to see trends, and by comparing them to your grazing system, you can alter and adjust in order to arrive at your goals.

Record keeping is a very important part of pasture monitoring. In addition to recording the aforementioned physical measurements, keep track of when livestock enter and leave a pasture, what if any materials or chemicals are used, revegetation or weed control treatments, and observations on cattle health while in the pasture. This information will be extremely useful in refining your grazing plans.

To obtain more detailed information on rangeland monitoring contact ATTRA at
800-346-9140.

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Managing for Drought

Drought is a natural ecosystem process. The concept of an “average” or “normal” precipitation or temperature is a fabrication that humans use to try to understand complex systems and attempt to predict behaviors and outcomes. Whether in a humid zone or an arid environment, a producer will experience relative wet and dry years. Dealing with the dry years is a real challenge to livestock operations that rely on water to grow the plants and recharge the aquifers and streams that feed the animals.Having a drought plan is a very important component of a well-thought-out farm or ranch management plan.

A drought-management option that deserves serious consideration is one that maintains livestock numbers at 75 percent of carrying capacity for “normal” years, and utilizes the extra forage in wet years for high value animals such as stockers. (Ruechel, 2006) In dry years the pastures will be better able to accommodate current livestock numbers. Another option is to slow down rotations during dry years, thereby allowing more paddock or pasture rest time. This option can be effective especially when the herd is split between different pastures to minimize the impact on drought stressed plants.

If you must de-stock during drought, consider which animals should be the first to go. Do you have low producing females? Do you have older calves that can be sold as stockers? Whichever you do, be sure not to de-stock too late. Pasture that is overstocked and drought stressed is hard to repair, whereas cattle can be bought when rains return.

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Plant Toxicity

Graziers must pay careful attention to the negative health effects that certain plants can cause in livestock. Plant toxicosis occurs either through the ingestion of (1) poisonous plants or (2) forage plants that contain toxic substances due to environmental or physiological conditions. Plant poisoning, as can occur from water hemlock, nightshade, or astragalus, can be significantly reduced by proper grazing management. These poisonous plants contain resins, alkaloids, and/or organic acids that render them unpalatable. If the pasture contains enough good forage, there is little reason for the animals to select bad-tasting plants. Contact your local Cooperative Extension office for information on poisonous plants in your area.

The following section illustrates some of the more common and economically important environmentally or physiologically caused disorders.

Bloat

Livestock can bloat when they consume vegetative legume pastures such as clovers and alfalfa. Bloat is a condition manifested by the distention of the rumen, noticed as a severe protrusion on the animal’s left side caused by fermentation gasses that are not able to escape. Legumes are high in protein, and the more immature the plant, the higher the concentration of proteins it contains. These proteins are very rapidly digestible and produce gas very quickly, faster than the animal can expel. Control is accomplished one of four ways:

• ensure the legume component is less than 50 percent of the pasture stand composition,
• feed one-third of the daily dry matter requirement as long-stem grass hay before grazing lush pastures that contain greater than 50 percent alfalfa or clovers,
• plant a non-bloating legume like Cicer milkvetch, sainfoin, and birdsfoot trefoil
• feed an anti-foaming agent. Antifoaming agents are usually fats, oils, or synthetic surfactants.

Organic producers must make sure to not feed prohibited materials. Any treatments they use or plan to use must be listed in the organic system plan and approved by the organic certifier.

Grass Tetany

Grass tetany is caused by low blood levels of magnesium (Mg). When succulent cool-season grasses are grazed early in the spring, the condition can occur quickly (have rapid onset). Symptoms include lack of coordination, staggering, and eventual death. Grass tetany is prevented by:

• delaying spring grazing,
• feeding a legume hay with spring grass pastures (legumes are higher in Mg than grasses),
• providing a mineral supplement,
• grazing early spring pastures with less-tetany prone animal such as steers, heifers, and cows with older calves. Pre- and post-partum cows are most susceptible to grass tetany.

Prussic Acid

Prussic acid, or hydrocyanic acid, is a toxin that occurs in annual grasses such as Johnsongrass, sorghum, and sorghum-sudan hybrids. When these grasses are stressed due to drought or frost, prussic acid levels accumulate and, if grazed by livestock, will cause salivation, labored breathing, and muscle spasms. Death can occur very quickly after consumption. Prussic acid does not persist as do nitrates. Forage that has been ensiled or harvested as hay and dried to less than 20 percent moisture is safe for consumption. Prussic acid poisoning can be prevented by:

• testing for prussic acid if conditions are right
• avoiding grazing for a week after the end of a drought. Young plant tissue after a drought-ending rain will be high in prussic acid
• avoiding grazing for a week after a killing frost
• considering using pearl millet as a warm-season annual forage (pearl millet does not produce prussic acid)
• avoiding turning hungry livestock into a suspect pasture

Testing for prussic acid requires timely delivery to the lab, as cyanide levels decline after the plant is harvested. Refrigerate but do not freeze samples if you cannot get them to the lab right away. If mailing samples to the lab, mail them on a Monday to reduce the chances that the sample sits in a post office over the weekend.

Contact your local Cooperative Extension office for information on forage prussic acid testing.

Nitrates

All plants contain nitrates, which are the precursor to plant proteins. Excess nitrates will accumulate in the lower stems of some plants when they are stressed, such as can occur during a drought, heavy rain, or long period of cloudy weather. In effect, nitrate accumulation occurs when photosynthesis slows down. During this time the plant may not be metabolizing nitrates, but it will still be taking nitrates from the soil. The result is a “back-log” of poisonous nitrate in the plant stems. Concentrations of 1.5 percent or more in plant tissue can be toxic to livestock, and concentrations of less than 0.25 percent are considered safe. Excess nitrates can be deadly to livestock and the most commonly affected plants are annual grasses such as the cereal grains (oats, wheat, and barley), warm season annual grasses (sorghum, pearl millet, and corn), and broadleaf plants like pigweed, thistles, goldenrod, and lambsquarters. In contrast to prussic acid, nitrate toxicity in forage does not decrease with time. Nitrate poisoning can be prevented by:

• testing of suspected plant tissue prior to feeding
• harvesting or grazing suspected forages several days to a week after the end of a drought
• beginning harvest or grazing of suspected forages in the afternoon after the plants have had several hours of sunlight (this helps the plants metabolize nitrates)
• chopping of forage and dilution with clean hay
• minimizing nitrogen fertilization.

Contact your local Cooperative Extension office for information on forage nitrate testing.

Fescue Toxicosis

Another important condition to consider in the South and Midwest is fescue toxicosis, which is caused by fungi growing symbiotically with the plant. Three distinct ailments can occur when livestock consume infected tall fescue. Fescue foot results in fever, loss of weight, rough hair coat, and loss of hooves or tail switch. Bovine fat necrosis is a syndrome characterized by hard fat deposits in the abdominal cavity. Summer slump is evidenced by fever, reduced weight gain, intolerance to heat, nervousness, and reduced conception. Fescue toxicosis can be reduced by:

• seeding of legumes to dilute fescue intake
• early close grazing of fescue to reduce seed development
• restricting nitrogen fertilization to the summer when warm-season grasses are actively growing
• replanting with endophyte-free seed or another grass specie such as orchardgrass

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Final Thoughts

When a livestock farmer relies on pasture or rangeland to supply the protein and energy requirements of livestock, it benefits the farm, the watershed, and the community in significant ways. Pasture-based animal agriculture promotes environmental stewardship and community development owing to the following management practices:

• Use of off-farm inputs, such as diesel, fertilizer, and purchased feed, are minimized.
• Use of toxic substances, such as herbicides and soluble fertilizers, is minimized or sometimes eliminated.
• Limited tillage and use of perennial pastures, which store carbon in the soil while building soil organic matter, conserves soil.
• Water and energy resources are conserved through monitoring and appropriate technologies, such as irrigation monitoring, solar and wind technologies, and biofuel development and use, where applicable.
• Proper plant and animal genetics, such as locally-adapted pasture grasses and low-maintenance animals, are selected.
• Planned grazing systems that favor grass growth contribute to biological diversity.
• Marketing food to local communities, reducing the distance food travels from farm to plate, provisions the community with better, fresher food.
• The development of local processing plants is fostered, which adds value to local animal products while providing employment and economic development.
• A management philosophy is developed that values health in people, animals, plants, and soil.

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References

Conservation Commission of the State of Missouri. 1984. Native Warm-Season Grasses for Missouri Stockmen. www.mdc.missouri.gov/documents/landown/1_040C.PDF (PDF / 104K)

Gerrish, J. 2004. Management-intensive Grazing: The Grassroots of Grass Farming. Ridgeland, MS: Green Park Press.

Lindemann, W.C. and C.R. Glover. 2003. Nitrogen Fixation by Legumes, Guide A-129. Las Cruces, NM: New Mexico State University Extension.

Montana DNRC. 1999. Best Management Practices for Grazing in Montana. Helena, MT: Montana Department of Natural Resources.

NCAT. 2004. Organic Livestock Workbook: A Guide to Sustainable and Allowed Practices. Butte, MT: National Center for Appropriate Technology.

Ruechel, J. 2006. Grass-Fed Cattle: How to Produce and Market Natural Beef. North Adams, Mass.: Storey Publishing.

SRM. No date. Rangeland Resources of North America. Lakewood, CO: Society for Range Management. Article accessed at www.rangelands.org/publications_brochures.shtml

USDA. 1997. Conservation Practice Standard, Prescribed Grazing, Code 528A. USDA Natural Resources Conservation Service. www.aces.edu/department/aawm/al528a.pdf
(PDF / 94K)

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Resources

ATTRA Publications

Assessing the Pasture Soil Resource
Dairy Resource List
Managed Grazing in Riparian Areas
Multispecies Grazing
Nutrient Cycling in Pastures
Pastures: Sustainable Management
Pastures: Going Organic
Paddock Design, Fencing, and Water Systems for Controlled Grazing
Rotational Grazing
Cattle Production: Considerations for Pasture-Based Beef and Dairy Producers

Fertility Pastures.
Newman Turner. Faber and Faber, 24 Russell Square, London.

Classic text on herbal lays, soil health, and profitable livestock production on pasture. Out of print. Used bookstores and interlibrary loan might yield good results obtaining this worthwhile book.

Foraging Behavior: Managing to Survive in a World of Change; Behavioral Principles for Human, Animal, Vegetation, and Ecosystem Management.
Fred Provenza, PhD, Utah State University. www.behave.net/products/booklet.html

Forage Information System
http://forages.oregonstate.edu/index.cfm

A comprehensive Web site for forage-related topics, including publications, educational opportunities, and professional resources. Maintained by Oregon State University.

Grazing management: an ecological perspective
by Rodney K. Heitschmidt and Jerry W. Stuth. Published by Timber Press, Portland, OR. Available on the web at http://cnrit.tamu.edu/rlem/ textbook/textbook-fr.html

This book was written “to help resource managers broaden their perspective relative to management of grazing animals and heighten awareness of the role they play in maintaining the integrity of ecological systems.” (from the Foreword)

Grazing Systems Planning Guide.
Kevin Blanchet, University of Minnesota Extension Service. Howard Moechnig, Natural Resources Conservation Service. Minnesota Board of Water & Soil Resources, Jodi DeJong-Hughes, University of Minnesota Extension Service. University of Minnesota Extension Service Distribution Center, 405 Coffey Hall, 1420 Eckles Avenue, St. Paul, MN 55108-6068 order@extension.umn.edu. You can also download it at www.extension.umn.edu/distribution/livestocksystems/DI7606.html.

Delineates the components of a grazing system by taking the farmer through the grazing management planning process.

Holistic Management International. 1010 Tijeras Ave. NW, Albuquerque, NM 87102, 505-842-5252, e-mail: hmi@holisticmanagement.org, Web site: www.holisticmanagement.org

HMI is a goal-oriented decision-making system for ecological management of resources, people, and capital.

Intermountain Planting Guide.
USDA Agricultural Research Service, Utah State University, Logan, UT. Order from USU Extension Publications, 435-797-2251, http://extension.usu.edu/cooperative/publications

Management-intensive Grazing: The Grassroots of Grassfarming.
Jim Gerrish, Green Park Publishing

This book can be obtained through The Stockman Grassfarmer’s Bookshelf at 800-748-9808. The industry standard for growing and managing pastures for sustained livestock production.

Pastures for profit: A guide to rotational grazing.
Cooperative Extension Publications, 45 N. Charter St., Madison, WI 53715, www1.uwex.edu/ces/pubs

Grazing ecology, and setting up a rotational grazing system.

Pasture for Dairy Cattle: Challenges and Opportunities.
Donna M. Amaral-Phillips, Roger W. Hemken, Jimmy C. Henning, and Larry W. Turner. University of Kentucky Cooperative Extension. www.ca.uky.edu/agc/pubs/asc/asc151/asc151.pdf (PDF / 179K)

Rangelands West. Western Rangelands Partnership, Agriculture Network Information Center, University of Arizona, http://rangelandswest.org

Web-based educational tools and information to assist resource managers improve rangelands and maintain sustainability.

Southern Forages.
Donald M Ball; C S Hoveland; Garry Lacefield, Altanta, GA: Potash & Phosphate Institute: Foundation for Agronomic Research, ©1991. Third Edition 2002.

Stockmanship: Improving rangeland health through appropriate livestock handling.
Steve Cote. P.O. Box 819, 125 So. Water St., Arco, ID 83213, 208-527-8557. Order from the Natural Resources Conservation Service, and the Butte Soil and Water Conservation District or available on the web at: www.mt.nrcs.usda.gov/technical/ecs/range/stockmanship.html

Quivira Coalition. 1413 Second Street, Suite 1, Santa Fe, NM 87505, 505-820-2544, www.quiviracoalition.org/index.html

Publications on ecological resource management including range management, grazing, road construction, monitoring, and managing resources at the urban-rural interface.

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Further Resources

Ball, D., C. Hoveland, and G. Lacefield. 1991. Southern Forages. Norcross, GA: Potash and Phosphate Institute.

Bellows, B. 2001. Nutrient Cycling in Pastures. Butte, MT: NCAT.

Blanchet, K., H. Moechnig, and J. DeJong-Hughes. 2003. Grazing Systems Planning Guide. St. Paul: University of Minnesota Extension Service.

Coffey, L. 2006. Meat Goats: Sustainable Production. Fayetteville, AR: ATTRA.

Klopfenstein, Terry. 1996. Need for escape protein by grazing cattle. Animal Feed Science Technology 60: 191-199 (no. 3-4, August).

Lacey, J., E. Williams, J. Rolleri, and C. Marlow. 1994. A Guide for Planning, Analyzing, and Balancing Forage Supplies with Livestock Demand. Bozeman, MT: Montana State University Extension.

Minson, Dennis J. 1990. Forage in Ruminant Nutrition. New York: Academic Press, Inc.

Sheley, R.L., T.J. Svejcar, B.D. Maxwell, and J.S. Jacobs. 1999. Healthy Plant Communities, MT199909 AG. Bozeman, MT: Montana State University Extension.

Undersander, D., B. Albert, D. Cosgrove, D. Johnson, and P. Peterson. 2002. Pastures for Profit: A Guide to Rotational Grazing. Cooperative Extension Publishing, University of Wisconsin-Extension.

Pasture, Rangeland, and Grazing Management
By Lee Rinehart
NCAT Agriculture Specialist
Paul Driscoll, Editor
Tracy Mumma, HTML Production
IP306
Slot 301

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