ANTHELMINTIC RESISTANCE OF TRICHOSTRONGYLIDS IN SHEEP IN THE HIGHVELDOF ZIMBABWE

A survey was conducted on the occurrence of anthelmintic resistance of trichostrongylids on commercial sheep farms in the highveld of Zimbab we. On ten farms the efficacy of fenbendazole, levamisole and rafoxani de was tested by a faecal egg count reduction test. Benzimidazole resi stance was additionally examined using an egg hatch assay with thiaben dazole. Results of the faecal egg count reduction tests and larval dif ferentiations showed fenbendazole resistance of Haemonchus sp. on all investigated farms. Resistance of Haemonchus sp. against rafoxanide wa s demonstrated on all farms with reliable egg counts. Levamisole resis tance of Haemonchus sp. was found on most farms but 2 farms showed an efficacy of 100%.