J. Paul Mueller and James T. Green, Jr., North Carolina State University
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.
The purpose of controlled grazing is to improve efficiency of forage use, eliminate negative environmental impact, and to improve net farm return.
Advantages of controlled grazing management compared with traditional pasture management include:
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.
A new management system will present new challenges. Below are some common problems and suggested solutions:
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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
The information presented in this publication is intended as a general guide to controlled. Adjust it to your local conditions and management style.