Abstract
An ivermectin ‡ ‡ Stated to be 22,23-dihydroavermectin B1. Supplied by Merck Sharp and Dohme (N.Z.) Ltd., as test material. View all notes formulation, MK 933, when administered subcutaneously at the rate of 200 ώg/kg to steers aged 12-14 months, gave a significant (POstertagia (predominantly O. ostertagi) spp. The lowest, median and highest post-treatment counts of early and later fourth stage worms combined were: controls 33,000, 143,500, 233,000; animals treated with MK 933; Trichostrongylus axei.