genetic parameters for resistance to haemonchus contortus in merino sheep in south africa.resistance to natural infections of haemonchus contortus (wireworm) was studied in merino sheep. from february 1995 to july 1996 data were collected from the otk merino stud on the farm wildebeesfontein near hendrina in mpumalanga province. from march 1998 to january 2000 another merino flock at irene in gauteng province was included in the study. in both cases, 50 randomly-chosen animals from each group of lambs weaned were sampled weekly for faecal egg count (fec) until a mean of 2500 eggs per ...200212088074
how long before resistance makes it impossible to control some field strains of haemonchus contortus in south africa with any of the modern anthelmintics?this paper describes an exceptional spectrum of multiple anthelmintic resistance in two strains of haemonchus contortus in south africa, one from howick in kwazulu-natal, and the other from badplaas, in mpumalanga. apparently for the first time, a helminth strain is described with resistance to compounds from all five of the modern anthelmintic groups used for nematode control in sheep; also, two strains of h. contortus show resistance to the two substituted phenols, dinitrophenol and nitroxynil ...19979195715
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