OVERBERG RESEARCH PROJECTS .16. 1ST-STAGE LARVAL REDUCTION TEST VERSUS THE CONTROLLED ANTHELMINTIC TEST TO ASSESS THE EFFICACY OF ANTHELMINTICS AGAINST NEMATODE PARASITES OF SHEEP

Results of a first-stage larval reduction test (L1RT) were compared wi th those of a controlled anthelmintic test (CAT) done on naturally inf ected sheep which grazed on spray-irrigated grass/legume pastures at T ygerhoek Experimental Farm near Riviersonderend in the southern Cape P rovince. The 3 anthelmintics used were morantel, ivermectin and levami sole. According to the L1RT, treatments reduced the geometric means of Strongyloides by 74,2 to 95,2 % and those of the adults of all the ot her genera (Haemonchus, Nematodirus, Oesophagostomum, Teladorsagia, Tr ichostrongylus and Trichuris) by 99,4 to 99,75 %. By contrast the resu lts of the CAT were more variable, placing the reliability of the L1RT in doubt. In addition, the CAT could also evaluate the effect against fourth larval stage Teladorsagia.