Controlled grazing includes any system in which the producer controls the grazing pattern of the cattle. It is known by many names, such as rotational grazing, intensive grazing and strip grazing. The best term to use might be 'rotational stocking' because it describes more accurately what is occurring- a large pasture subdivided into several smaller pastures (called paddocks) by cross fencing and animals stocked in one of the paddocks. When the forage has been removed, cattle are rotated to the next paddock.
The major expense involved with growing or maintaining cattle is feed cost. Because grazing is usually the least expensive means to provide nutrients to livestock, a primary goal of beef cattle producers should be to utilize pasture for as many months of the year as possible and minimize dependence on stored feed. This sounds very simple in theory, but in reality is often difficult to accomplish.
The difficulty relates to the seasonal growth pattern for most pastures. Tall fescue is the predominant forage in most Tennessee pastures, and is most productive during spring and fall, but high temperatures and limited rainfall during the summer cause a decrease in growth (Figure 1). This fluctuation in forage production creates a dilemma for cattle producers. How many cattle can be carried on the farm? If stocking rates are based on summer forage production, excessive spring growth will result in pastures that are undergrazed, forage will mature and drop in quality, and large amounts of forage may be wasted because of selective grazing and trampling. If pastures are stocked based on spring growth, then overgrazing during summer months could damage plant stands, and result in the need to supplement the diet of the grazing animals. If stocking rates are set somewhere in between, then there will be problems in both seasons, even though they will be less severe.
Figure 1. Yield distribution of tall fescue during the year.
One solution to the stocking rate problem is to buy or sell animals every couple of weeks, depending on the amount of forage produced. If pastures are growing well and getting ahead of animals, then a few head can be purchased to increase grazing pressure. If pasture growth slows, then a few animals can be sold to decrease grazing pressure. Animal numbers could be adjusted as necessary to prevent under or overgrazing. This is not a practical solution, however, because of health and behavioral problems which invariably occur with frequent changes of this nature.
The method that can best be used to match forage production to livestock numbers is not by changing the number of animals stocked on the farm but by increasing or decreasing the amount of pasture that they have access to. This is the concept behind controlled grazing. The number of paddocks created by cross fencing may vary from only a few to 12 or more. The animals may be stocked on the paddock for 1-2 days up to a week. Size and number of paddocks, as well as the length of time livestock have access to a paddock are decisions each producer should make based on their specific situation.
Phenomenal claims have been made about the benefits of controlled grazing. Everything from doubling forage production to eliminating fertilizer applications has been listed. For controlled grazing to be worthwhile, the ‘bottom line’ needs to be improved profit, which can occur through more efficient utilization and harvest of forages. There are several factors that work together to make controlled grazing a successful management tool. Following are brief discussions of advantages of controlled grazing.
1. Increase beef production per acre- This is the primary reason for improved profitability with controlled grazing. Research has shown that stocking rates can usually be increased with controlled grazing. This results in more pounds of beef produced per acre (Figure 1). Concentrating more animals on a smaller area of land forces them to graze more of the available forage and waste less. The average daily gain of individual animals may not increase, and might actually decrease. But there should be and increase in beef production per acre, which is a direct result of increased stocking rate because of improved forage utilization and less forage going to waste.
Figure 1. Yield distribution of tall fescue during the year.
2. Easier to use excess forage for hay production- Because smaller paddocks are more uniformly grazed and less forage is wasted, surplus forage from ungrazed paddocks can be harvested for hay. During the spring, abundant forage production might result in one or two paddocks being used exclusively for hay production instead of grazing. When production declines during the summer, these paddocks can be included again into the grazing rotation pattern.
3. Improve persistence and productivity of many pasture species- Plants such as orchardgrass, endophyte-free tall fescue and alfalfa are not tolerant of the stresses associated with close, continuous grazing. Rotational stocking allows these plants to rest for several weeks after grazing. This rest period allows sensitive plants time to regenerate food reserves and recover from the trauma of grazing. Certain plant species, such as white clover, are not as competitive and tend to be sensitive to shading by other plants. Allowing a pasture to grow tall without being grazed or clipped may result in the death of these plants due to a lack of light and excessive competition from other plants. Rotational stocking results in paddocks that are grazed or clipped at least once every 4-6 weeks, thereby preventing the prolonged shading that may cause the loss of shade-intolerant plants in a pasture.
4. Better livestock husbandry- Experience has shown that livestock often become more docile and easier to handle when they are managed using a controlled grazing system. The animals become trained to move from paddock to paddock, and will often be waiting near the gate. In a rotation system, livestock are observed more often, which results in the opportunity to determine any health problems that may occur.
5. Improve pasture management skills- The key concept in controlled grazing is the movement of livestock depends on the forage availability in paddocks. This requires that producers frequently observe and evaluate forage growth and the amount of forage removed by grazing. Frequent observation causes producers to become more aware of the characteristics of the pastures, both in terms of overall production and species composition.
By utililizing an effective grazing system, the producer gains control of the grazing animal, and therefore gains control of how forage plants are managed. Each farm is different, as is each manager and each season, so there is not a single “best” method of controlled grazing. Decisions concerning paddock size, when livestock should be moved, where fences should be placed, etc., are often based on judgement and experience. Controlled grazing is very much an art that is learned by ‘doing’. When the system is being designed it should be kept as simple and flexible as possible.
The first requirement for controlled grazing is fencing. Permanent boundary fences should be established to hold livestock on the farm. Temporary fencing can be used to split large pastures into smaller paddocks. Interior fencing is often some type of electrified single-strand fence that is easily constructed. There are many types of fencing that can be effective in restricting areas to which animals have access.
Paddock Size, Layout, and Number
The next step in initiating a controlled grazing system is dividing a large pasture into paddocks. Keeping in mind that the goal of controlled grazing is the efficient use of forage, the degree of control producers have over grazing livestock increases as size of paddocks decrease and number of paddocks increase. Some producers may want to gain very close control, to the extent that cattle are moved each day. In this case 25-30 paddocks will be needed. A general rule of thumb for paddock size and number is that 5-7 days should be required to remove the available forage from the paddock. If more days are required , then plant regrowth from areas already grazed will be utilized in preference to existing forage. Ideally, following this 5-7 day grazing period will allow 3-4 weeks of rest. This will require 5 or 6 paddocks. Remember that forage production will vary according to the season. During the spring, paddock size may need to be decreased to be grazed in a week. This will result in a greater number of paddocks, some of which will be cut for hay. As forage growth slows during the summer, livestock can be rotated quicker among paddocks , or paddock size can be increased. All paddocks do not need to be the same size or shape. Long, narrow paddocks that are 4-5 times longer than their width should be avoided. Livestock will often not graze them uniformly, and long traffic lanes often encourage soil erosion. Several factors need to be considered when dividing pastures:
(1) Water - fences should be placed so that existing water sources can be used as efficiently as possible. Paddocks can sometimes be laid out so livestock in two or three paddocks can be watered from a single source. If new water sources need to be provided, keep in mind that the system should be kept as flexible as possible, and that fences are temporary and may be moved at various times during the year. When designing the watering and fencing systems, try to limit the distance cattle have to travel to water to no more than 600-800 feet.
(2) Topography - the lay of the land is a major factor determining paddock layout. Areas with steep slopes should be fenced so they can be grazed first, since these areas are difficult to harvest for hay. Bottom land should be harvested for hay and grazed as needed during the year. Whenever possible, arrange paddocks to minimize cattle movement “up and down” slopes. This will decrease erosion potential due to cow paths.
(3) Soil type - Oftentimes, the forage production potential from different areas of a large pasture is dramatically influenced by the soil type. Even if the same forage is grown on both soils, the amount of grazing that will be provided between areas may be different enough to warrant division by a fence.
Many times producers plant forage species based on soil type. For instance, to use alfalfa for grazing, a field that is deep and well-drained should be selected. Different forage species should be fenced separate from each other because of the different management and production characteristics of various plant species.
Filling Production Gaps with Different Forage Species
One of the major goals of cattle producers should be to provide grazing forage to their cattle for as much of the year as possible. This will reduce the hay requirement, which is one of the most expensive components of a cow-calf operation. It will also help to reduce the amount of time in which the pastures are overgrazed because forage demand exceeds forage production. This overgrazing results in poor cattle performance, but also contributes to poor stand persistence and increased weed pressure. When trying to decide which forages to use on a farm, several factors need to be considered. A step-by-step process can help make the decision a lot easier. In fact, it can often make the decision obvious. Following are the items that should be considered.
(1) Determine your farm's current forage production curve. Before adding any new forages, it is important to determine what are the best and worst production seasons for your farm. In general, if cool-season grasses form the base of a program, spring and fall are productive periods, while summer is a period of forage deficit.
(2) Select forages that complement the current program. If a new forage species is to be added, be sure that its production will improve the farm's forage availability during the time of the year when forage is lacking. If a pasture is planted to a cool-season grass, when all the other pastures are already producing during the spring and fall, the problem of poor summer production has not been helped.
(3) Use perennials over annuals, if possible. In general, forage from perennial pastures is more economical and dependable, with less risk of environmental problems. Establishment costs can be prorated over several years, whereas annuals must be seeded every year. A minor drought can be devastating to the establishment and production of an annual crop, while it may only reduce or delay the production of a perennial pasture.
(4) Consider the forage quality needed by the herd. The forage selected should be able to provide the appropriate quality for the animals on the farm. A forage that is too low in protein or too high in fiber will reduce the performance of grazing cattle. If a forage is higher in quality than is required by the grazing animals, it will not be used efficiently. A spring-calving cow herd does not have very high nutrient requirements during the summer, so a medium quality forage like bermudagrass will be more economical than alfalfa. However, if a producer is stockering beef calves, the high quality of alfalfa may be a profitable forage because of the high nutrient requirements of these animals.
(5) Consider the ease of management. If all other characteristics are similar, choose the forage that will be the easiest to manage and maintain. Forages that require a high level of management to produce and persist will be more difficult to deal with than a forage that is persistent under the stressful conditions that can occur in Tennessee. In general, grasses are easier to maintain and require less careful management that do legumes.
For most operations in Tennessee, tall fescue is the primary forage. The ease of establishment, persistence and long production season make it an excellent species to use for cow-calf operations. The biggest weakness in forage production with tall fescue comes during the summer months. The cool-season perennial grass does not produce well during the hot, dry summer conditions (Figure 2). Since the summer is the period with the greatest lack of forage, a warm-season forage is the best choice for a type of species to add (Figure 2). Seeding a new field to orchardgrass will not help the summer forage lack, and will only add more forage during the spring and fall. If the cattle on the farm are a spring calving cow herd, minimal forage quality is needed by the cows during this period. Warm-season grasses are probably the best choices.
Figure 2. Growth curves of cool vs. warm-season grasses.
Movement of Animals Between Paddocks
A controlled grazing system will not be effective just because animals are rotated. The system is effective because a producer is better able to manage the cycles of abundant and limited forage production. Movement of animals and harvest of excess forage should be based on the amount of forage available in the paddock.
A producer should not rotate animals to a new paddock on a specific time schedule, but should move them based on the amount of forage in the paddock, and on the rate of growth of the forage. As stated earlier, a 5-7 day grazing period is optimum for most producers. Following the recommendations, the first month it may take four days to graze a paddock, while the next month it may take six days. The difference may be caused by temperature, rainfall or many other factors. Regardless of the reason, moving animals based on forage availability and forage growth allows producers to be flexible and efficiently utilize the forage produced, while rotation on a fixed schedule might still result in a certain level of under or over-grazing.
In the spring when all of the paddocks begin to grow at the same time, it will be necessary to start grazing in some of the paddocks before the optimum amount of forage is present. If grazing is delayed until all paddocks have the optimum amount of forage, then paddocks later in the grazing sequence will get too mature before livestock are modved into them. The paddocks grazed early should be grazed to the recommended height, which may take only a couple of days.
There are many opinions concerning the value of clipping a paddock after grazing. Harvesting all forage by grazing or clipping is ideal, but seedhead production during spring sometimes results in the need for amid-summer clipping of paddocks to remove old seedheads. This can also be timed to help remove weeds before they produce seed.
AN OVERVIEW OF CONTROLLED GRAZING- Dr. Gary Bates
he University of Tennessee Institute of Agriculture
2621 Morgan Circle, Knoxville, TN 37996