The effects of a controlled-release albendazole capsule (Proftril-Captec) on parasitism in grazing Corriedale ewes in the Nyandarua district of Kenya.

摘要

The effects of intraruminal sustained-release capsules (IRSRCs) containing albendazole on parasitism in grazing Corriedale ewes were investigated over 119 days (4 June to 30 September 1993) using 40 ewes of about 2 years of age and divided into 2 groups of 20 ewes each. Each ewe in the treatment group received an IRSRC and the controls were untreated. The groups were placed on adjacent 2.5-acre paddocks obtained by subdividing a 5.0-acre permanent pasture which had previously been grazed by young untreated sheep. The faecal egg counts, herbage larval counts and worm burdens of the major gastrointestinal parasites of sheep were significantly reduced by the use of the IRSRC. Identification of larvae obtained by coproculture indicated that Haemonchuscontortus eggs predominated in both groups followed by Ostertagia spp., Trichostrongylus spp., Cooperia spp., Oesophagostomum spp. and Nematodirus spp. The IRSRC-treated ewes also had increased live weight gains and heavier fleeces. The control ewes required occasional salvage treatments during the trial and the herbage on their paddock was heavily contaminated with infected larvae. High worm burdens were found in control ewes on PM examination at the end of the trial as were also found in 3 sets of two 5-month-old tracer sheep introduced into the paddocks during the initial (day 30), interim (day 58) and final (day 89) stages of the experiment. The tracers were allowed to graze for 2 weeks before being removed and housed under parasite free conditions for 3 weeks before killing and PM examination. Most capsules were exhausted within 95 days of administration and there was a rise in the faecal egg counts in the treated group towards the end of the study.