Pennisetum clandestinum

Abstract

DISTRIBUTION: • Mainly utilized as a pasture or a lawn grass, but it also escapes and grows in moist fertile places in the wild. • It grows naturally in the highlands of Kenya, Uganda, Tanzania, DRC, Ethiopia, Rwanda and Burundi. • It has been introduced to many other parts of the world.

BOTANICAL DESCRIPTION: General: This is a dense mat-forming perennial grass that has both stolons and creeping rhizomes. Leaves: Leaf blades are flat, folded or rolled with a prominent midrib and leaf sheaths are overlapping. Flowers: During the flowering season (August - April) long white filaments can be seen, but there are no visible inflorescences.

TOXIC PRINCIPLE: • Grass invaded with Spodoptera exempta (army worms, kommandowurms). • The worms themselves are not toxic and the kikuyu grass in itself appears to be non-toxic, but a combination of these two results in toxicity through an unknown mechanism. • It takes ±10 days for the grass to become toxic after an army worm infestation and the toxicity is retained for 4 - 6 weeks after the worms have gone (life-cycle is completed, or they are killed by insecticides). Rumenitis can also occur when the grass was not previously invaded by army worms, but when there was a growth spurt during hot weather, following high nitrogen fertilization and irrigation of kikuyu.

SYSTEMS AFFECTED: Gastro-intestinal system.

CLINICAL SIGNS: Latent period of 24 hours or longer. 1. Gastrointestinal signs: • Ruminal atony and tympany. • Colic: Grunting and kicking at the abdomen • Usually a constipation. • Ruminal irritation results in an excess accumulation of fluids, sloppy ruminal contents which may gush from the mouth and nose at death. • It also results in severe dehydration with sunken eyes and a unpliable skin. 2. Neuromuscular signs: • Bulbar paralysis (“shamdrinking” and severe salivation due to inability to swallow). • Muscle tremors• Ataxia, the animal lies down and rises with difficulty. Dies 2 - 4 days later. Most deaths within 48 hours.

NECROPSY: Macroscopical findings: • Excess and severely fluid ruminal contents (bright green). • Hyperaemia and large necrotic areas of the forestomach mucosa. • Severe dehydration.

HISTOPATHOLOGY: Non specific.

TREATMENT: • Symptomatic and supportive. • A high percentage of affected animals die.

PREVENTION AND CONTROL: • Prevent infestation of pasture. • Control worms with pesticides. • Withdraw animals from pasture for at least 40 days from last army worm presence. • Test for toxicity by using less valuable tracer cattle for four days prior to allowing rest of herd back onto pasture.