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Seedhead |
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Bermudagrass
(Cynodon dactylon)
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Bermudagrass is a bluish-green, perennial sod
grass having both rhizomes and long stems or runners that take
root at the nodes. The internodes are flattened. The seed head
has three to six purple spikes and resembles a bird’s foot.
Along one edge of the seed are hairs visible only with a microscope.
Many varieties and hybrids of bermudagrass have been planted
throughout the state.
Distribution and habitat
This plant or its hybrids are found in all regions of Texas.
It is the most important warm-season perennial grass planted
for improved pastures in the state. Regions: 1,
3, 5,
6, 7,
8, 9,
10.
Toxic agent
The toxic agents in bermudagrass are not known. Two of the
toxic syndromes associated with this plant are related to
fungal growth. The first syndrome, bermuda-grass staggers,
results from an unknown tremorgenic mycotoxin produced by
an endophyte (a fun-gus within the plant). Seen only in cattle,
the staggers syndrome may result from the consumption of the
stable toxin in hay or from pastures, usually in the fall.
The second syndrome produces liver damage and secondary photosensitization
when the grass being grazed has a heavily moldy thatch beneath
it. A third disease, fog fever or pulmonary adenomatosis,
occurs when extremely lush bermudagrass is grazed. This grass
contains unusually high levels of the amino acid tryptophan,
which is converted by rumen microbes to the lung toxin 3-methyl
indole.
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Livestock
signs
Bermudagrass staggers is similar to dallisgrass staggers except
that there is less hyperexcitability. Signs become pronounced
upon exercise and there may be:
• Head bob
• Muscle tremors
• Incoordination
• Collapse when forced to make rapid movement
• Inability to regain feet
• The condition worsens if the animal is
assisted.
The staggers syndrome is reversible, and most cattle recover
unless there is a fatal accident. Animals with liver damage
caused by bermudagrass have photosensitization. Those with
fog fever have severe breathing difficulty, and can die from
lack of oxygen.
Integrated management strategies
Remove cattle with staggers from the toxic hay or pasture,
supply them with feed and water and allow them to remain
as quiet as possible. Complete recovery may take up to 3
weeks. Hay and grass in the pasture should be destroyed.
Place animals with secondary photosensitization in shade,
feed them sun-bleached hay having no green color and treat
them symptomatically. Feeding monensin, a feed additive
that shifts the population of rumen microbes, may prevent
fog fever problems. Vacate pastures causing the problem
for 14 days.
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