Comparison of the post-parturient rise in faecal egg counts of indigenous and cross-bred ewes

The breed differences in post-parturient rise (PPR) in faecal egg counts in lambing ewes of different breeds naturally infected with Haemonchus contortus were compared. The ewes of Nali, 50% Nali x 50% Russian Merino/Corriedale and 37.5% Nali x 62.5% Russian Merino/Corriedale were treated with fenbendazole while ewes of the above three breeds as well as 25% Nali x 75% Russian Merino/Corriedale, were kept untreated. Observations from 3 weeks before lambing to 12 weeks post-lambing at weekly intervals revealed that in treated ewes, egg counts of Nali did not differ significantly with 50% Nali whereas 37.5% Nali had significantly higher egg counts than those of Nali and 50% Nali. In untreated ewes egg counts of 50% Nali were significantly higher than that of Nali on some occasions, while 25% Nali had significantly higher egg counts than the other three breeds. None of the ewes from the Nali breed showed signs of haemonchosis, whereas few lambing ewes of the three Nali crosses (50%, 37.5% and 25% Nali) showed signs of haemonchosis and one ewe of the latter breed died.