Sudangrass (forage sorghums) contains a compound called "dhurrin," which isbroken down in the digestive tract to release cyanide. This occurs
particularly easily in ruminants, due in part to the neutral pH of the
rumen and/or the repeated crushing affects of chewing cud. (I've read that
cattle are slightly more susceptable than sheep, but I wonder how that data
was developed.)
In any case, sudangrass contains much higher levels of dhurrin when it is
young (and short) than when it matures. Therefore, the common prudent
recommendation is to never graze sudangrass when it is less than 18 inches
tall. Some varieties have lower levels of dhurrin than others, but I would
recommend to your farmer to keep animals off until the grass is at least
18". Sudangrass that is 18" tall is still a good feed.
Also, young regrowth of sudangrass, like after a droughty period or after
fertilization, can have high concentrations of dhurrin.
Woody
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Woody Lane, Ph.D. | Nutrition & Management Consulting
Lane Livestock Services | voice: 541-440-1926
240 Crystal Springs Lane | fax: 541-440-1007
Roseburg, OR 97470 | email:
[email protected]
