Parasites of sheep at the international Livestock Centre for Africa Debre Berhan station, Ethiopia

Abstract

Prevalence of gastrointestinal parasites was investigated using monthly faecal samples and necropsy data in sheep treated regularly and irregularly at the International Livestock Centre for Africa research station at Debre Berhan. Maximum infection rates with nematodes, Fasciola and coccidia in the irregularly treated sheep were 18%, 10% and 37%, respectively, compared with 5%, 3% and 41% for the host treated regularly. Strongylosis was diagnosed mainly in July–November (wet-early dry) season, fasciolosis in January–June (late dry-early wet) season and coccidiosis all the year round. Signs of helminthiasis occured in August–November, primarily in the irregularly treated flock. A single deworming of the latter flock with fenbendazole (November) resulted in low worm-egg output and the absence of clinical helminthiasis as in the regularly dewormed flock. The management of the supplementary feeding of the untreated flock resulted in weight gains superior to the treated group during the entire 1987 period. Haemonchus contortus, Trichostrongylus colubriformis, T. axei, Ostertagia spp., Trichuris ovis, Chabertia ovina and Fasciola hepatica were helminths encountered at necropsy. Free-living stages of H. contortus and Trichostrongylus spp. may appear on pastures in May–July and July–September, respectively. Two broad-spectrum anthelmintics given at the start of the long and short rains should suffice to control the endoparasitism.