RESISTANCE OF NONLACTATING EWES AND LAMBS OF INDIGENOUS AND CROSSBREDS TO NATURAL INFECTION WITH HAEMONCHUS-CONTORTUS

The resistance of non-lactating Nali, 50% Nali x 50% Russian Merino/Co rriedale, 37.5% Nali x 62.5% Russian Merino/Corriedale and 25% Nali x 75% Russian Merino/Corriedale ewes naturally infected with Haemonchus Contortus was compared. No significant differences were found between ewes of Nali and 50% Nali while 37.5% Nali and 25% Nali ewes tended to show higher egg counts. Further, the susceptibility of weaned lambs b elonging to Nali and its crosses (50% and 37.5% Nali) showed no signif icant differences except significantly higher body weights in 50% Nali lambs compared to Nali. Sentinel lambs indicated that pastures were c ontaminated.