University of Vermont

Article Pasture Management Through the Season

Sid Bosworth, Extension Associate Professor, Department of Plant and Soil Science, University of Vermont sid.bosworth@uvm.edu


Spring Management
It is important to consider that what you do with your pasture in the spring can determine what will happen for the rest of the year in terms of pasture and animal productivity. Here are a few things to consider that might help you improve pasture and animal performance.

  • Start grazing on time. Spring is when grasses have the highest growth rate during the year. If you start too late, the animals will never catch up. A good rule of thumb is to start grazing when the grasses reach about 3 inches in height if it is Kentucky bluegrass or 4 inches in height if it is a tall grass like orchardgrass. Once your animals have moved through the rotation, you can allow grazing to begin when bluegrass reaches 5 to 6 inches or tall grasses, 7 to 10 inches.
  • Adjust stocking rate so animals keep up with the grass. Besides a high growth rate in the spring, grasses also have the urge to produce a seed head. Once that process starts, your grasses have definitely gotten away from you. The results can have a significant negative impact on your pasture. Forage quality goes down. The pasture is usually poorly utilized. Tillers that grow from the base of the sward (the foundation for summer production) will be inhibited because of lack of light. Legumes, such as clovers, are also inhibited to grow because of competition by the tall, rank clumps of grass.
    • The best way to control this is to have a stocking rate that keeps up with the grass growth and inhibits or delays the grasses ability to send up a seed head. Stocking rate is simply the number of animals per acre grazing. In the spring, you might start with about one animal unit (1000 lb cow) per half acre. In other words, a 30 cow herd would run on about 15 acres in the spring. You may need to make adjustments from this depending on the productivity of your pasture.
    • If possible , divert the rest of your pasture area for hay or silage. This means that you should put your worse ground into spring grazing (that land that cannot be harvested). If you cannot divert half of your pasture toward an hay harvest, you might consider adding additional animals to your spring pasture program. This might include backgrounded youngstock or stockers. Another option - make an arrangement with neighboring dairy farmers to graze their dry cows and heifers during this period.
  • Manage the pasture so that it is grazed at least twice before June 1. This is easiest to do if you have a Voison type rotational grazing system. By checking the regrowth of the earliest grazed paddocks, you can decide when to start the second rotation. The rest of the pasture that is ungrazed is then used for hay. If your animals are grazing one large area, it is more difficult to monitor but a temporary fence can be used to adjust stocking rate.
  • Supplement with a magnesium mineral supplement to prevent grass tetany. This is especially important for cows soon to freshen or with calves at side that are grazing predominantly grass pasture. Avoid fertilizing the pasture with potash or fertilizers containing potash in early spring as this will make grasses more "tetany prone." If your pasture has a significant amount of legume, it is much less likely to cause a tetany problem.
  • During the first week of grazing, slowly introduce animals to pasture and supplement with some dry hay to avoid bloat. This can be a problem when hungry animals quickly consume clovers, alfalfa or even young, lush grass.
Summer Management
With adequate pasture available, most livestock farms should be able to provide a relatively inexpensive feed during the summer months. Only during periods of extended drought, should there be a need to supplement cows with hay or silage. Here are a few things to consider that might help you improve pasture and animal performance during the summer months:
  • Allow an adequate rest period between grazings utilizing rotational grazing. Base this on the regrowth of the pasture, not a certain number of days. In the summer months this may be anytime between 25 and 40 days depending on weather conditions. In most pasture systems, areas will vary in soil productivity, thus, pasture growth rates will also vary. Therefore, it is best to not to use a set rotational scheme but move animals to those paddocks that have reached their optimum available pasture. Rule of thumb: allow grazing to begin when tall grasses reach 6 to 7 inches in height or short grasses such a Kentucky bluegrass when they reach 5 to 6 inches.
  • Avoid overgrazing. Animals must be moved when the available pasture falls below its optimum range or animal performance will decline. As a rule, remove animals when grass heights are 2 to 3 inches for tall grasses and 1 to 2 inches for bluegrass.
  • Supplement if necessary. If pasture becomes short during summer dry spells, it is often tempting to just let the animals continue to move through the pastures eating what they can. If pasture plants are eaten too often and too close, both plant production and animal production will decline. When pasture becomes short, either supplement with hay, haylage or increase pasture acreage.
  • Forward creep graze your calves. Calves need a higher quality pasture than brood cows. Utilizing a "creep" gate can allow growing calves to graze the next fresh paddock and still return for suckling, much the same principle as a creep grain feeder. Forward creep grazing can also allow you to force the cows to clean up each paddock before moving them, without jeopardizing the growth of the calves.
  • Begin stockpiling pasture in late summer. If you have additional pasture or hay ground, you can use this for late fall grazing. Simply keep the animals off starting in mid- August. If the pasture is primarily grass, you can increase it's productivity by applying approximately 50 lbs of nitrogen per acre (about 100 pounds of urea). Allow this pasture to "stockpile" until your other pastures are completely grazed in the fall. Then you can strip graze this pasture in late fall.


Fall Management
Although you can get significant forage during the fall months, it is also a time of preparation for winter and the next year. The following are some thoughts on managing in the fall.

  • Soil test early in the fall to determine any lime, phosphorus, potassium or magnesium needs. Fall is a good time to do this and to apply most soil amendments.
  • Manage your crops so that you reduce the risk of winter injury. This will vary somewhat according to the particular species.
    • It is generally recommended to avoid grazing Timothy, smooth bromegrass, red clover and birdsfoot trefoil from early September to mid-October to allow for adequate accumulation of energy storage. A late grazing after mid-October may be made, but only graze down to about 4 to 6 inches. This allows enough stubble to catch snow and protect the basal portions of the plants.
    • Other species such as orchardgrass, bluegrass, perennial ryegrass, tall fescue or white clover are not as sensitive and can be grazed throughout the fall months. These grasses can also tolerate a quicker rotation. However, too short of a grazing or harvest interval can still deplete energy reserves and weaken a stand. If the stand has been subjected to many grazings through the year, it would be best to give it a longer rest period before grazing.
    • For alfalfa in Vermont, it is generally best not to take a fall grazing or harvest. It reduces yield the following year and increases the risk of winter injury. If you do harvest in the fall, be sure there has been at least 45 days since the last cut and that your soil potassium level is up to optimum on your soil test. If not, apply some right after a late summer grazing or harvest while there is still time for the plants to take some up before they go dormant. Also, leave 4 to 6 inches of stubble to help catch any snow during the winter.

This site is maintained by Sid.Bosworth@uvm.edu, Plant & Soil Science Department, University of Vermont.

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Last modified May 26 2004 01:29 PM

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