Seasonal incidence of infective trichostrongyle larvae on pasture grazed by lambs

Abstract

Abstract Seasonal fluctuations in numbers of infective larvae on herbage of two pastures were determined by regular pasture sampling from January 1967 until August 1969. During this period eight genera of nematode larvae were recovered, viz, Trichostrongylus, Ostertagia, Haemonchus, Cooperia, Nematodirus, Bunostomum, Chabertia , and Oesophagostomum . Larval recoveries suggest a fairly regular annual pattern, with a small peak of larvae in the spring and a larger peak in the autumn. The more common nematode larvae occurred in both the spring and the autumn peaks, many of the genera overwintering on the pasture each year. A relationship exists between larval availability and climate.