The effects of late turnout on the epidemiology and control of ostertagiasis in calves.

The main purpose of this experiment was to study the importance of time of turnout on the epidemiology and impact of ostertagiasis in calves pastured for the first time. When time of turnout onto permanent pasture was postponed from mid-May to mid-June, fewer overwintered larvae were picked up and re-contamination of pastures was markedly diminished. Consequently, the acquisition of loss-producing parasite burdens in the late part of the season was significantly reduced. Late turnout as a control strategy is discussed in relation to other preventive measures.