CONTROLLED GRAZING

J. Paul Mueller and James T. Green, Jr., North Carolina State University

WHAT IS CONTROLLED GRAZING ?

Controlled grazing is a method for regulating how often and how much to graze in order to control the quality, yield, consumption and persistence of forage from pasture. Controlled grazing attempts to optimize animal performance and reduce wasted forage. The area of fresh pasture provided to a set number of animals for a given period (known as stock density) is changed to control the amount of forage eaten, its quality, and how long each pasture is rested between grazings. In this way, it is possible to match pasture growth with the animals' requirements. Surplus growth is conserved as hay or silage, while growth shortages are made up by careful feeding of supplements.

WHAT IS ITS PURPOSE ?

The purpose of controlled grazing is to improve efficiency of forage use, eliminate negative environmental impact, and to improve net farm return.

WHAT ARE THE ADVANTAGES ?

Advantages of controlled grazing management compared with traditional pasture management include:

• Increased animal production per acre.

• Improved botanical composition of pasture (increased legume).

• Improved yield and monthly distribution of forage.

• Improved distribution and recycling of nutrients from animal manure and reduced mechanical handling .

• Improved soil conservation and water quality.

• Improved animal handling and allocation of pasture forage due to positive changes in animal behavior.

• Reduced need for machinery, fuel and facilities.

• Reduced supplemental feeding requirements.

• Reduced fluctuations in the quantity and quality of forage grazed by animals.

• Reduced wasted forage from pasture.

WHAT ARE THE DRAWBACKS OF CONTROLLED GRAZING ?

With any relatively new management practice there will be some negative aspects which will keep some managers from trying it. Nevertheless, most of the disadvantages associated with controlled grazing are perceptions based on traditional management and not based on cost-benefit evaluation of the practice.

• Initially, there will be an investment of time and money for fence construction, gates and lanes.

• The need to supply drinking water and shade in every paddock is a perceived problem which can be economically solved. The perceived need to access shade throughout the year may prevent full development of enough subdivision on many farms.

• The small paddock size could make it inconvenient to use the currently owned machinery.

• The concern about increased soil compaction and treading damage from high stock density on small paddocks.

• The managerial abilities will have to change to more fully realize the potential of the system. In other words, simply developing more paddocks without improving grazing skills will not give good return on investment.

• There is a perception that labor demands will increase. Labor management will have to change because moving cattle frequently is a task that has not been customary on most farms.

WHAT CAN GO WRONG AND WHAT TO DO ABOUT IT ?

A new management system will present new challenges. Below are some common problems and suggested solutions:

Problem:

Moving animals on fixed schedule (for example every 7 days) or following a set movement pattern for each grazing cycle regardless of the amount of forage in the paddocks reduces plant and animal production.

Solution: Base decisions to move animals on to and off of paddocks on a predetermined pasture height (amount of forage present). For example, start grazing when the pasture canopy is between 6 and 8 inches and end when the average canopy height has been grazed to between 2 and 4 inches.

Look at the growth in all paddocks on a regular basis (every 6-12 days) and make a record of which paddocks have the most growth and graze them according to the amount of forage present in each area. Pay attention to the stubble or residue in a pasture after grazing; don't let it get too short before moving to the paddock which is nearest the desired stage (height) for grazing.

Problem:

Animals are getting out of the paddock.

Solution: This usually happens when the electrical power on the fence is too low (below 2000 volts) or when the feed supply within the paddock is not enough to satisfy the animals hunger.

Check the voltage on the fence and follow the guidelines in your energizer manual concerning "trouble shooting". Inadequate earth return system ("ground") and inadvertent short circuits are the most common problems. In some cases it may be necessary "retrain" an animal to electrical shock. If certain animals tend to be repeat offenders, a one-way ticket to the sale barn is appropriate. One or two animals with bad habits can cause other animals to become a problem.

Problem:

Daily animal performance is less than that obtained under previous management.

Solution: If you have been using continuous grazing during much of the year at a low stock density, gain per head may have been better than you are currently experiencing under controlled grazing. It is impossible to obtain maximum daily animal performance and maximum production of meat or milk/acre at the same time. Therefore, it is necessary to determine the value of improved output/acre relative to the reduced individual animal performance.

Adjust by altering how much pasture feed is available just before and just after grazing. Usually animal performance is best when there is a moderate amount of feed remaining in the pasture (about 1200 to 1500 lbs/A) when animals are moved to the next paddock. The acre production is best when most of the feed is used in a relatively short grazing time (leaving behind 800 to 1000 lbs/A).

Problem:

High stock density causes severe compaction or hoof treading of pasture during wet weather.

Solution: When soil conditions are such that animals are making severe hoof impressions and destroying the sod it is advisable to move them onto hard surfaces such as lanes, or into woodlots, or into a "sacrifice paddock". If the soil in a paddock is firm, such as on most permanent pastures, it is often sufficient to move the animals onto the tallest grass (more than 6 inches) for very short periods of time. The tall grass and frequent movements minimize the damage.

Problem:

A Heavy concentration of manure and urine near the central drinking water and shaded areas reduces distribution of nutrients in the pasture system.

Solution: Distribute water to every paddock so that animals do not congregate in a single spot for more than 1 to 3 days during each grazing cycle.

Minimize the use of centralized shade. Unless temperatures or heat stress index is high, don't worry about supplying shade to animals. During stress periods use paddocks which have shade or graze unshaded paddocks from late afternoon until mid morning.

Problem:

Internal Parasites reduce production.

Solution: Rotational grazing is sometimes cited as beneficial in reducing parasite problems, but controlled grazing could actually result in an increase in parasite burden because pasture forage is usually grazed uniformly to moderately short stubbles and because pastures are frequently regrazed before parasite larva are killed from exposure to hot, dry conditions.

Special care should be taken with young, growing animals such as calves, lambs and kids. These animals are highly susceptible to infection and may require regular treatment with appropriate worming medications. The use of schemes that alternate mechanical harvesting and grazing of forage or alternate grazing of pastures with different animal species (i.e. cows following lambs) may also be effective in reducing parasite problems.

Rarely will it be economical to extend the grazing cycle as a method of parasite control; forage quality deteriorates rapidly after 15 to 30 days.

Problem:

Failure to conserve surplus forage reduces carrying capacity and output of the grazing unit.

Solution: Surplus pasture growth is conserved as hay or silage that will be fed during periods when pasture growth is very slow.

Periods of conservation can be anticipated and provisions for hay or silage making can be made well in advance. Other methods of managing surplus include adjustment of animal numbers during critical periods and the use of deferred grazing. For example, the unit could be managed to have the maximum animal feed requirement coincide with maximums of surplus growth by selling or buying animals at the appropriate time. The grazing of autumn stockpiled of tall fescue is often helpful in matching forage production to animal needs. Cropland and crop residues can sometimes be conveniently "flexed" in and out of the grazing unit to address this problem.

HOW DOES THE SYSTEM WORK?

TIPS FOR DESIGNING A CONTROLLED GRAZING SYSTEM

1. Select adapted plants for year-round grazing.
   • Develop a perennial pasture system based on warm and cool season species which are productive and persistent for your soils, climate and management.

   • Use legumes such as such as clovers and alfalfa in mixture with grasses to the extent that soils will permit legume growth.

   • Grow warm season perennial grasses on 20 to 30 % of the land area on farms where soils permit the growth of both cool and warm season perennials.

2. Minimize land dedicated only to hay making.
   • In some situations because of remote location or terrain considerations surplus forage must be obtained by cutting hay or silage from the same field(s) year after year.

   • Making hay of surplus growth from grazing paddocks can help in weed control and parasite control but the use of dedicated "hay fields" reduces the flexibility of management because these fields are "off limits" to grazing animals. When this is the case no recycling of waste occurs, only off-take of nutrients with the hay.

3. Use lime and plant nutrients wisely.

4. The yields of pasture plants are directly related to the nutrients supplied by fertilizer, manure and lime.

5. Soil test the upper 2-3 inches of soil at least every two years to guide the application of nutrients.

6. Monitor the clover (legume) composition of pastures 3-4 times per year to aid in determining the nitrogen requirements of pastures. The goal is to maintain a uniform distribution of at least 25 to 35% clover (legume) in the pasture mixture.

7. Use controlled grazing to provide uniform grazing pattern and recycling of nutrients from urine and manure. Over several years this management will reduce the fertilizer requirement.

8. Manage to grow green leaves.
   • Young, green leaves are 70 to 80 % digestible, whereas brown leaves and mature seed heads are only 30 to 40 % digestible.

   • Graze the leafy, vegetative paddocks with milking dairy cows, cows with calves, growing animals such as heifers and stocker cattle that have high nutritional requirements.

   • Graze dead plant tissue and stems containing seed heads with animals that have low nutrient requirements such as dry, pregnant brood cows, ewes or mares.

   • Clip or mow pastures to regenerate new vegetative growth only when they can't be grazed or harvested for hay or silage.

9. Subdivide the grazing unit and cross fence to control the grazing pattern.
   • Create 10 to 20 permanent pastures or paddocks. The optimum number of paddocks on a farm will vary with topography, soils and plant types.

   • Use fences to separate pastures that differ in growth rate, palatability, exposure, etc. Subdivide fields to separate:
     • hill land from bottom land

     • sunny slopes from shady slopes

     • shallow soils from deep, productive soils

     • areas planted to different plant species

     • Use electric power fences to confine animals to the farm and to subdivide pastures. Boundary fences must be substantial enough to retain animals on the farm even if power fails.

     • Use internal cross fencing to ration out forage to the animals. In many cases one or two temporary electric wires will be sufficient. Use new technology materials such as reels, tread-in posts and polywire or polytape to reduce fencing costs.

10. Graze each area rapidly.
    Put enough animals on a paddock to graze to the desired stubble height in 1 to 3 days. A high stock density, equivalent to 20 to 70 animal units per acre (20,00 to 70,000 lbs. of live weight per acre) is usually needed to reduce wasted forage and obtain uniform grazing.

    Move animals from paddock to paddock based on plant height. For example, fescue-clover: on at 6 to 8 inches and off at 2 to 4 inches.

11. Anticipate changes in pasture growth.
    • If pastures accumulate more than 8 to 10 inches of growth take paddocks out of the grazing rotation and harvest this surplus as hay or silage at the correct stage of maturity.

    • Offer supplemental feed if supply of forage from pastures is limiting. Ration out autumn accumulated growth of tall fescue using temporary electric wire.

12. Provide a sacrifice area.
    • A sacrifice area is a drylot, woodlot or pasture scheduled for renovation. Keep animals in a sacrifice area when pastures are extremely wet or when pasture growth is insufficient to permit grazing.

    • Provide shade and water in the sacrifice area and use the area for supplemental feeding, thereby reducing treading damage or severe overgrazing of the paddocks. Plant growth in the sacrifice area will be severely damaged or eliminated.

13. Be flexible.
    • You must be prepared to make adjustments in the grazing or feeding program because pasture growth rate and animal requirements are continually changing.

    • Let the rate of grass growth and the amount of forage present determine when a paddock or area is to be regrazed.

    • The rule of thumb for controlled rotational grazing is: when grass is growing fast, use a short rotation cycle (12 to 20 days) and harvest the surplus growth as hay or silage; when growth slows, use a long cycle (30 to 60 days or more) and feed supplemental forage if needed. For example, during winter tall fescue may need 90 to 120 days (November to March) to regenerate enough growth to graze.

14. Get started.
    • Begin by using only a part of the herd or a small part of the farm. Expansion can come after you gain experience with the management system.

    • Keep the stocking rate on the farm about the same. Subdivide pastures and plan management schedule to allow the forage in each paddock to be grazed in 1 to 3 days.

    • Keep records of the amount of surplus forage harvested, the number of days each pasture is grazed, the sequence and length of the rotational grazing cycle, and seasonal animal performance.

A Summary of How the System Works

The shape, grazing sequence and size of pastures can influence forage utilization, animal performance and the efficiency of land and labor use.

The base number of permanent pastures or paddocks on the farm will be determined by topography, soils, and plant types. Keep in mind that permanent subdivisions can be further divided by using temporary cross-fencing. The best cross-fences are easy to move, yet effective in controlling grazing animals. In most situations 10 to 20 permanent paddocks will be sufficient to provide a flexible rotation. The number of "hot" wires needed for control depends on the type of animal being grazed.

Animals and number of wires

    Species      Number of Wires

Cows or stockers:        1 


Cows with calves:        2


Horses, mature:          1

Horses with foals:       2

Sheep:                  3-5

Goats:                  3-5

Size and shape of paddocks aid in the allocation of feed. In most cases it is impractical to make permanent paddocks smaller than one or two acres. Flexibility in size and shape of paddocks can be gained by subdividing permanent paddocks with temporary wire to gain control of grazing patterns as seasonal production of forage changes in response to temperature, moisture, and day length. If most paddocks are of similar size then it is likely that available forage within each enclosure will also be similar and the time required to grazed a paddock will be about the same. Square paddocks are the most efficient compared to other shapes (pie shaped, fan shaped, narrow rectangles) because animals can obtain their daily feed with a minimum of time, effort and trampling of the pasture sward. Also, cost associated with subdivision fence are reduced with squares compared with other shapes. Try to avoid long, narrow paddocks. Wherever possible, fence across slopes rather than up and down the slopes.

Controlled grazing will help you to anticipate changes in pasture growth. During periods of rapid growth some paddocks ahead in the rotation will accumulate more forage than can be effectively used (more than 8-10 inches). Close these paddocks out of the rotation cycle and harvest them for hay or silage at the correct stage of growth to best compromise yield and quality. If tall, rank growth must be grazed, be sure that stock density exceeds 70,000 pounds of live weight per acre per day so that as much forage as possible is consumed with minimal waste.

In this situation it is best to use animals with moderate to low requirements since forage quality is likely to be poor.

Water can be provided in each paddock by using above or below ground plastic pipe equipped with quick couple points so that portable water tanks can be moved from paddock to paddock with a minimum of effort. This will result in maximum grazing time and a more uniform distribution of manure over the grazing paddocks. Water can also be accessed through a well-designed system of gates and lanes (within 1/2 mile of the grazing area), but this will result in concentrations of animal waste in the watering area and a transfer of nutrients from the grazing paddocks. When farm ponds are the water source, it is best to fence out the pond and siphon water into float-valve-controlled stock tanks.

Shade is needed only during extremely hot weather (temperatures above 85 F). It can be accessed through a lane system similar to that mentioned for a centralized watering area. When pasture forage constitutes only part of the ration, grazing can take place during the cool mornings or evenings or at night.

Handling or milking facilities that connect the pastures through a well designed lane system are very convenient to grazing and animal management activities, however, the location of these facilities should not prevent the implementation of a grazing system.

Record keeping can aid pasture management by providing a basis for decision making such as when to cut surplus growth, when to move animals, projecting grass growth, and in the timing for fertilizer applications. Records include but are not limited to: pasture or paddock ID, dates of grazing each paddock, animal numbers on the paddock, soil test results, fertilizer used, an estimate of plant composition and results of periodic forage tests of the grazable forage. Checks of animal performance (live weight gain or milk yield) can be made to gauge the results of grazing management decisions.

Generalized Grazing Management Guidelines for Plant Species in the Mid and Upper South

Species[Note 1]      Start Months  |--- inches----|
                                      [Note 2]           Days to Rest
                                   to start to stop   Before Regrazing

Fescue-clover          Feb-Mar      4-6       2-3          30-45

fescue-clover          Apr-Jun      6-8       2-4          14-30

fescue-clover          Jul-Aug      6-8       3-4          30-60
  
fescue-clover          Sep-Oct      6-8       3-4          21-35

fescue-clover          Nov-Jan      4-12+     1-2          60-120

bermudagrass           Apr-May      2-4       1-2          21-30
  
bermudagrass           Jun-Jul      2-4       1-2          10-21

bermudagrass           Aug-Sep      2-4       1-2          20-40

alfalfa                Apr-May    3 to bud    3-4          10-21

alfalfa                Jun-Oct    bud-bloom   2-3          21-40

alfalfa                Nov-Dec     before     2-3          90-120
                                  leaf drop
         

NOTES:

1. Orchardgrass may be treated much the same as tall fescue. Alfalfa grazed prior to bud stage should be permitted to reach 10 to 25% bloom before the next grazing cycle.

2. Strive to graze the forage in a field within 3-days (to minimize waste and quality changes).

GRAZING UNIT DESIGN

REMEMBER:

The information presented in this publication is intended as a general guide to controlled. Adjust it to your local conditions and management style.