Craig C. Sheaffer, University of Minnesota
The information presented in this fact sheet is not intended to take the place of professional legal advice. In developing any written lease agreement, it is highly recommended that all parties seek professional legal advice.
It’s estimated that about one fourth of the country’s current Conservation Reserve Program (CRP) acres will become grazing lands when contracts expire. For the many CRP acres that are highly erodable, grazing might be the most effective way to harvest forage. Grazing systems can provide adequate forage for livestock while maintaining environmental quality.
There are two major types of grazing management: continuous and controlled. With continuous grazing, the livestock decide what and when they eat. Fencing, watering, and labor inputs are lower for continuous grazing than for controlled grazing. With controlled grazing, the farmer manages and controls the duration and extent of pasture use. There are several variations of controlled grazing (see Table 1).
Some advantages of controlled grazing include:
Under intensive rotational grazing systems (see Table 1), livestock generally graze several paddocks in sequence. Fields are rested between grazings. For example, milking cows usually graze new forage every 12 hours, providing them with fresh forage and minimizing the waste from defecation and trampling. Beef cows and sheep, in contrast, use paddocks for up to a week. Graziers can maximize profits with properly developed rotational grazing systems. Table 2 compares advantages and disadvantages of intensive rotational grazing, continuous grazing, and confinement feeding systems.
Forages Graziers can meet livestock nutrient needs by providing season-long availability of nutritious, palatable, non-toxic forage. Season-long grazing is best achieved using a combination of permanent and cropland pastures.
The leading forage plants in many pastures and CRP lands are perennial grasses such as smooth bromegrass and quackgrass (see Persistence of Planted Forages on CRP Land in this series). These grasses produce more forage in the spring than in mid-summer. This uneven production does not meet the nutritional needs of most livestock. One solution lies in diversifying forages in pastures. Diversification can help graziers get uniform yields of quality forage throughout the season.
Perennial legumes can improve seasonal forage production. However, their coverage of CRP fields that were planted to cool season grasses or grass-legume mixtures is only 23 percent. Graziers should consider introducing perennial legumes like birdsfoot trefoil, alfalfa, or kura clover into these fields. To avoid legume bloat in livestock, legumes should be mixed with perennial grasses. Forages with complimentary yield patterns should be selected (see Renovating CRP Lands for Forage Production in this series).
Graziers should consider whole-farm pasture systems that include both permanent pastures on former CRP land and cropland pastures. Many CRP lands are highly erodable. Pastures on these lands will be most productive in the spring and fall and should be the backbone of the pasture system. Permanent pastures can be supplemented with cropland pastures during the summer and other periods when forage deficits exist. Cropland pastures may be planted with perennial legumes such as alfalfa or other annual crops such as brassicas and sudangrass. Some cropland pastures can be harvested for hay in the spring when not being grazed. New lightweight, portable fencing systems help convert cropland to pasture quickly.
Livestock graze for extended periods of time confined by a single perimeter fence.
Producers manage forage availability, quality, and utilization.
Livestock graze from 2 to 40 or more sub-pastures or paddocks in sequence.
Intensive rotational grazing (also called management intensive grazing)
A rotational grazing system in which the grazing period is typically less than 4 days.
A predetermined amount of forage is allotted to the animal on a daily, weekly, or longer basis.
A rationed grazing system in which a pasture is grazed in strips to enhance the utilization rate. No further grazing is anticipated. If regrazed, it would be a rotational system.
Livestock graze a limited amount of high quality forage for a short period, usually once or twice daily, as a supplement to lower quality forage.
Rotational grazing involving two groups of livestock with different nutritional needs. The group with higher requirements grazes a paddock first to select prime feed. The second group grazes after the first group has been moved to a fresh paddock.
Forward creep grazing
A modified first/second grazing system using cow-calf pairs. Calves are first grazers but retain access to the paddock where the second grazer cows are confined.
Source: Adapted from Gerrish, 1990 (see Other Resources #3).
Grazing and rest periods
Within a week following grazing, most grasses and legumes will begin regrowth. Therefore, short grazing periods of 1 to 3 days will improve the persistence of desired forages by preventing grazing of the regrowth. Grazing periods that are longer than one week deplete the supply of palatable legumes and grasses as livestock actively seek these forages.
Forage legumes like alfalfa, red clover, and birdsfoot trefoil usually will not remain unless their reserves can be replenished with a 4-week rest period. Therefore, in continuously grazed pastures, perennial grasses are the predominant species after a few years. Cool season grasses like smooth bromegrass, timothy, and Kentucky bluegrass need a short rest of 2 weeks during cool weather and 5 to 7 weeks during hot weather. Warm season grasses need 5 to 6 weeks of rest when it’s cool and about 3 weeks during hot weather.
Since crop development can be affected by temperature, drought, and fertility, it’s important that plant development be used to decide when to start grazing. Livestock usually begin grazing legumes when they are 10 to 12 inches tall. Tall-growing grasses such as smooth bromegrass or orchard grass are grazed when they reach 7 to 12 inches. Kentucky bluegrass is consumed starting at 4 to 5 inches.
Intensive Rotational Grazing
Source: Minnesota Department of Agriculture, Sustainable Agriculture Program
Height of grazing
The height to which forage is grazed determines the amount of leaf area left for regrowth and, consequently, the rate of regrowth. The higher the remaining stubble, the more rapidly the plant will regrow following grazing. Most legumes and tall-growing grasses should be grazed to a 2- to 4-inch stubble height, followed by a 4-week rest period. Since plant tops are leafy and usually high quality, the height of grazing can influence animal performance. Animals with high nutritional needs, such as milking cows, can increase their energy intake by eating only the tops of plants. Forward creep feeding (see Table 1) is an example of this type of grazing management.
Stocking rates and herbage allowance
Herbage allowance greatly influences animal performance and per-acre production. When livestock have high herbage allowance due to low stocking rates, their individual performances increase but the total production per acre decreases (see Figure 1). At low stocking rates, high gain per head occurs because animals can graze high quality forage, but overall yield per acre is low because forage is wasted. At higher stocking rates, competition among animals for forage increases and gain per head decreases. However, gain per acre is usually greater. The stocking rate and herbage allowance necessary to get the best balance between gain per head and gain per acre vary with grazier goals.
Supplementing pasture forages
The diets of grazing cows must be balanced to meet their nutrient requirements. Pastures should be sampled and tested to determine the nutrient concentration. Forage consumption also should be estimated.
It’s generally believed that milk production from cows grazing high quality pastures is limited primarily by the intake of digestible energy. Supply of bypass protein is a second limiting factor. Cows consuming high quality pasture that is low in fiber often need to be fed hay. The supplemental feeding of energy and bypass protein can have a major effect on milk production and cost. Ultimately, the cost-effectiveness of rotational grazing is determined by balancing the cost of feed supplements and the return per unit of milk.
Modern Fencing Systems
The development of new fencing materials has advanced rotational grazing. Modern fencing systems consist of perimeter and subdivision fencing of high-tensile wire and lightweight portable fencing for temporary subdivision. Modern fence energizers repel livestock effectively and are more reliable than older systems. Modern low-impedance energizers deliver a stronger shock. Today’s systems are less likely to fail due to faulty insulators or contact with vegetation. (See Other Resources #3 for more information on fencing.)
Barbara Weisman, Conservation Program Specialistbarbara.email@example.com or 1-800-967-2474Ag Marketing & Development Division