Epidemiology of nematode infections of weaner sheep in the cereal zone of South Australia

Abstract

Trichostrongyloid nematode infections of weaner sheep were investigated at the Turretfield and Minnipa Research Centres in the cereal zone of South Australia over a three-year period (1982-1985). Acquisition of nematode larvae from pasture occurred over a limited period each year, principally during the winter months, and coincided with the elimination of, or a reduction in the numbers of adult nematodes; sheep subsequently resisted challenge by infective larvae. Faecal egg counts were elevated during the summer, but declined to negligible levels during the winter months when larval challenge was at its maximum. Scouring, which was common in untreated sheep during winter at Turretfield, did not occur in regularly treated sheep, but no adverse effects were noted at Minnipa.