Parasitic gastro-enteritis of cattle: The distribution and survival of infective strongyle on pasture

Abstract

Observations are reported on the behaviour and longevity of infective cattle strongyle larvae in faecal pats and on pasture in south-eastern Queensland. Environmental conditions within the pat were favourable for the development of infective larvae at all seasons of the year except midsummer and midwinter. Larvae were distributed for the most part either in the pat or on pasture vegetation. Larvae migrated laterally from the pat for distances up to at least 3 ft, but usually not more than 1 ft, and these movements occurred only after suitable rain. At no time was a single mass movement of all larvae in the pat observed. If rainfall was continuous, migration was continuous, and when rainfall was alternated with periods of dryness, migration occurred in waves. Pats exposed in the summer remained a source of larvae for 5 months. This period was extended to 7–8 months with pats exposed in the winter. Larvae survived on pasture for up to 6 and 8 weeks respectively for these seasons of the year. Vertical migration on pasture was also observed.