Abstract
An investigation was undertaken to confirm the existence of a mebendazole-resistant strain of Ostertagia spp. on a ram-breeding property in Taihape. The results indicated that while a strain of Haemonchus conforms from this farm was highly resistant to mebendazole, an isolate of Ostertagia spp. was fully susceptible. Possible reasons for the discrepancy between previous and present findings are briefly discussed.