Melica decumbens

Abstract

DISTRIBUTION: It grows usually in the shade of trees or shrubs between rocks. Most common on hillsides, but also on plains and roadsides.

BOTANICAL DESCRIPTION: General: A relatively short, coarse, densely tufted grass. Leaves: Very coarse, erect and usually rolled. Flowers: The spikelets are covered with soft hairs and mostly arranged on one side of the axis. Glumes are papery and usually purple. October to April.

TOXIC PRINCIPLE: Indications are that mycotoxin producing endophytes are the cause of the syndrome.

SYNDROMES: “Dronkgras poisoning”.

SYSTEMS AFFECTED: Central nervous system.

CLINICAL SIGNS: A tremorgenic, usually non-fatal, not uncommon syndrome of cattle and sheep on Melica decumbens in late winter and early spring, following good winter rain in the eastern Karoo and Eastern Cape Province where this grass is prevalent. Essentialy identical to Kweek tremors. • Stimulation and exertion (exercise) often precipitate symptoms. • All stages of nervous derangement seen from: Hypersensitivity; Mild involuntary trembling to spastic tremors of individual muscle groups; Nodding of head, shaking of limbs or trunk. • Ataxia, stiff-legged gait, side-ways progression, falling and inability to get up to complete prostration (recumbency). • Some cases show hypersensitivity and paddling movements like heartwater. • Adopt position of sternal recumbency. Except for outspoken cases, animals remain alert and retain their appetites. When withdrawn from infected pastures recover rapidly over a few days.

NECROPSY: • Nothing specific.

TREATMENT: • Symptomatic. • Remove from infected pasture and allow to recover.