The UK Forage publication ID-143: Rotational Grazing provides a good overview of the goals of grazing management. “Good grazing management achieves the right balance between standing availability of forage, forage utilization, and animal performance. A good manager stocks pastures heavily enough to graze available forage down to a target height that will allow rapid and maximum forage regrowth (during the growing season) without compromising nutritional needs of livestock. A good manager will observe pastures frequently for overgrazing and undergrazing and will periodically adjust the stocking rate or movement of cattle as needed.”

This publication also provides a table with guidelines for beginning and ending grazing heights and usual days of rest for several pasture crops (see below). While all of these points are very important for good grazing management, the ending grazing height changes as you move into the late fall in preparation for winter. Simply put, you do not expect regrowth after grazing in the late fall. That’s your last grazing before the winter and then that pasture will be rested and not grazed until spring. Your main goal with fall grazing management is to ensure good regrowth next spring. Fall grazing management guidelines vary depending on the type of forage.

Cool Season Perennial Grasses — i.e. orchardgrass and tall fescue. During the grazing season, the recommended ending grazing height for orchardgrass is 3 to 6 inches and for tall fescue 3 inches. Our basic recommendation is to maintain a grazing height at or above 3 to 4 inches for these cool season grasses. Grazing to this height allows leaf area to remain after grazing for continued photosynthesis and energy production. Also, the base of each grass shoot or stem is where energy is stored for regrowth. In the late fall, it is not necessary to leave leaf area for photosynthesis since it will be frosted back over winter, but it is important to leave the base of the shoots so that energy storage remains for faster regrowth in the spring. In other words, a late fall ending grazing height of 3 inches is recommended so that your pasture will green-up sooner in the spring. The exception is when you are planning to frost seeding clover in February.

Tap-rooted Legumes — i.e. red clover and alfalfa. During the grazing season, the ending grazing height for alfalfa is 2 to 4 inches. The reason that close grazing is fine is that the energy reserves needed for regrowth are stored in the taproot below ground. This same principle holds true over winter since spring regrowth will come from these root energy reserves. With alfalfa and red clover though, close grazing in the late fall can lead to more weed growth over winter. In addition, leaving some stubble can help winter survival if there is a heavy wet snow or ice that freezes solid next to the ground. The stubble will prevent ice encasement from smothering the plant crowns.

Spreading Forages — i.e. Kentucky bluegrass and white clover. Both of these forage plants are referred to as “spreading” types. Kentucky bluegrass spreads by underground stems called rhizomes, and white clover spreads by above ground stems called stolons. Since both of these structures are either just below or just above the soil surface, they are not affected by grazing height. The thickness of rhizomes and stolons allows them to store energy needed for regrowth. In short, these forages can be grazed close in the late fall and will still show rapid green-up in the spring.

Warm Season Annuals — i.e. pearl millet, sudangrass, sorghum/sudangrass. Since these grasses are annuals, they will not regrow in the spring. During the growing season it is very important to leave a tall ending grazing height. The recommended 8-12 inches limits the removal of their growing point and leaves several nodes on the stem below grazing height. Both of these ensure a rapid regrowth after grazing. In the late fall though, it is fine to graze them as low as possible. A low grazing height is all the more important if you are seeding a winter cereal or new permanent pasture into this field.

Native Warm Season Grasses — i.e. eastern gamagrass, big bluestem, indiangrass, switchgrass. During the grazing season with native grasses, it is important to end grazing at an average height of 8 to 10 inches. Similar to the warm season annuals, this limits removal of the growing point and allows more rapid regrowth after grazing. With these grasses, their energy is stored at the base of the stems over winter. Therefore, it is fine to graze them much closer once they go dormant after frost. The most important fall grazing management is that you allow 6 to 8 weeks of regrowth before frost so their energy reserves are increased going into the winter.

Preparing for Frost Seeding

There is always an “exception to the rule” and this is definitely true in relation to late fall grazing when planning to frost seed in February. The standard recommendation is to graze as close as you can in the late fall or winter before frost seeding. A close grazing in the late fall or winter means less shading of the new clover seedlings when they emerge in the spring. In addition, close grazing slows down spring green-up which gives additional time for the clover plants to get started. This is one reason frost seeding works so well after close grazing of stockpiled fescue.

Categories: 
Fall
Extending the Grazing Season