Sorghum
General poisoning notes:
Sorghum (Sorghum bicolor) is a cultivated plant grown as ensilage, as poultry feed, or sometimes as broomcorn, for its long, flexible, high-quality broom fibers. Sorghum can contain a cyanogenic glycoside that can produce HCN during times of stress or if damaged by frost or mastication. Modern sorghums have been developed for their low HCN potential and are normally safe. Sorghum can also accumulate toxic levels of nitrates. Cattle and rarely horses have been poisoned (Kingsbury 1964, Gray et al. 1968, Clay et al. 1976).
Description
Annual. Culms erect, robust, 3–5 m tall, 2–5 cm in diam.; nodes glabrous or pubescent. Leaf sheaths glabrous or slightly farinose; leaf blades linear or linear-lanceolate, 40–70 × 3–8 cm, glabrous; ligule subrounded, ciliate. Panicle very variable, lax or dense, cylindrical or pyramidal to obovate in outline, up to 60 cm, main axis elongate to very short; primary branches ascending or spreading, lower branches sometimes almost as long as panicle, stiff or pendulous; racemes tough at maturity, composed of 2–6 spikelet pairs. Sessile spikelet variable, broadly obovate to subglobose, 3.5–5.5 mm; callus hispid; lower glume leathery to papery, glabrous to pilose, pale creamy-green to dark brown or blackish at maturity, upper lemma usually awned; awn 0.4–1.5 cm. Pedicelled spikelet male or barren, linear-lanceolate, persistent or deciduous. Caryopsis large, often exposed between the gaping glumes. Fl. and fr. Jun–Sep. 2n = 20.
Nomenclature:
Scientific Name: Sorghum bicolor (L.) Moench
Vernacular name(s): Sorghum
Scientific family name: Gramineae
Vernacular family name: grass
Sorghum bicolor (L.) Moench
Geographic Information
Plant or plant parts used in or around the home.
Notes on Poisonous plant parts:
Damaged leaves and stems can release HCN. Since HCN is volatile, silage made from this plant is generally safe (Cheeke and Schull 1985).
Toxic parts:
Leaves, stems.
Notes on Toxic plant chemicals:
In the presence of plant enzymes released by damage, a cyanogenic glycoside, dhurrin, produces hydrocyanic acid (HCN) in the animal''s system. Levels of cyanide at 250 mg/100 g of plant tissue have been measured after damage. A lethal dose of cyanide is 0.5-3 mg/kg of body weight. Some sorghum plants have been measured with levels 10 times a lethal of HCN (Cheeke and Schull 1985).
Toxic plant chemicals:
Dhurrin
Dhurrin
Nitrate
Chemical diagram(s) are courtesy of Ruth McDiarmid, Biochemistry Technician, Kamloops Range Station, Agriculture and Agri-Food Canada, Kamploops, British Columbia, Canada.
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
Cattle
General symptoms of poisoning:
Abortion, coma, convulsions, cyanosis, death, dyspnea, gait, staggering, methemoglobinemia.
Horses
General symptoms of poisoning:
Abortion, incoordination, urinary incontinence.
Notes on poisoning:
In the United States sublethal doses of HCN caused degeneration of the lumbar and sacral segments of the spinal cord in horses after they ingested sorghum. Large quantities of sediment occur in the urine. If forced to move, affected horses sway from side to side and dribble urine, a condition known as sorghum cystitis ataxia. Other symptoms include an extremely enlarged bladder and patchy encephalomalacia with axonal degeneration. Damage is permanent. When fed sorghums during early pregnancy, mares have aborted. The causal toxin has not been determined yet (Fuller and McClintock 1986, Morgan et al. 1990).
