Sunday, Dec 2, 2012
Garza County News

Photo by Texas AgriLife/Twain Butler


Grazing Johnsongrass

AgriLife Extension Extras

Published July 27, 2012 @ 6 a.m.

I have had a few calls over the last couple of weeks about grazing johnsongrass. Here is some general information concerning this topic.

Livestock producers can quickly lose animals if forage is not carefully monitored especially when pasture conditions in the area are continuing to decline due to droughty growing conditions. This has resulted in most pastures starting to have a late-summer appearance. One “forage” that seems to be surviving the drought and doing quite well, in many areas, is johnsongrass. With the lack of adequate grazeable forage, what is the possibility of grazing johnsongrass?

Johnsongrass is very competitive with other forage if left unchecked. It is also drought tolerant and is often one of the last plants to stop growing during a drought. Johnsongrass yields can approach 3 to 5 tons/acre under good growing conditions. Nutritive value estimates of 10% crude protein and near 60% TDN are common. In addition to nitrate toxicity potential, another potential negative to utilizing johnsongrass is that it has high potential to produce hydrogen cyanide (HCN). This is more commonly known as prussic acid. The forages used are most likely to produce toxic levels of HCN are the grain sorghums, johnsongrass, sorghum-sudangrass hybrids, and sudangrass.

Safety Measures

During droughts, grazing pastures that are mainly johnsongrass should be avoided, if possible. Do not rely solely on drought-damaged forages as the only source of forage. It is important to keep some other form of dry forage available at all times.

  1. Testing for prussic acid- especially during dry periods after small rain events.
  2. Do not graze cattle if they are hungry. Feed hay and begin grazing in late afternoon.
  3. Restrict grazing until plants are at least 24 inches tall. Young, succulent growth and regrowth has greater concentrations of HCN than more mature growth.
  4. Do not graze regardless of height within four days following a good rain. This is the time when rapid, new growth of young plant tissue occurs.
  5. Do not graze wilted plants or plants with young regrowth; ribbon-like appearance on the leaves is normally an indication of prussic acid.  The best management practice will be to harvest this as hay


Extension Extras

South Plains Fair Entries - If you are planning on entering, the South Plains Fair entries are due in the office on August 9th no later than 5:00p.m. For more information please contact the Extension office.

Goat and Lamb Validation Tag orders are due in the office no later than 5:00 p.m. on Wednesday, August 22. For more information please contact the Extension office.

Extension Office: 215 W Main (806) 495-4400
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.  The Texas A&M University System, U.S. Department of Agriculture, and the County Commissioners Courts of Texas Cooperating.

The copyright for all articles is held by the respective authors and/or The Garza Post. All rights reserved. Any publication, rewriting, or redistribution is prohibited without prior written permission.
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