Effect of the morantel sustained-release bolus, used during one grazing season, on the sensitivity of Ostertagia and Cooperia to morantel tartrate in calves.
Infective 3rd-stage larvae of Ostertagia and Cooperia, obtained from the feces of nonmedicated and morantel sustained-release bolus (MSRB)-treated calves, were orally administered to 2 groups of parasite-free calves. After a 42-day maturation period, a therapeutic dose of morantel tartrate was administered to half of the calves from each group. All calves were necropsied 7 days after treatment. After comparing the nematode counts for the nonmedicated and morantel-treated calves of each group, morantel tartrate was demonstrated to be equally effective against the nonmedicated-derived and MSRB-derived nematode populations. The sensitivity of Ostertagia spp and Cooperia spp to morantel tartrate, therefore, was not diminished after use of the MSRB for a single grazing season.
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D003692:Delayed-Action Preparations; D005243:Feces / Q000469:parasitology; D009015:Morantel / Q000494:pharmacology* / Q000627:therapeutic use; D010029:Ostertagiasis / Q000188:drug therapy / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D011743:Pyrimidines / Q000494:pharmacology*; D012621:Seasons; D014251:Trichostrongyloidea / Q000187:drug effects*; D014252:Trichostrongyloidiasis / Q000188:drug therapy / Q000662:veterinary*
D003692:Delayed-Action Preparations; D011743:Pyrimidines; D009015:Morantel