Seasonal changes in the level of infective strongylate nematode larvae on pasture in the coastal savanna regions of Ghana.

The level and type of infective strongylate nematode larvae on pasture were followed from March 1994 to April 1995 in the coastal savanna regions of Ghana. The number of infective larvae on pasture was high, reaching 2458 kg-1 dry matter of grass during the period of and soon after the rains, and very low or none in the absence of rainfall. The number of infective larvae on pasture was directly related to the pattern of rainfall, but it was also influenced by the number of raindays in the period. The following genera were found in order of prevalence: Haemonchus, Oesophagostomum, Trichostrongylus, Cooperia. The mean total adult worm burdens of tracer lambs released monthly were related to the levels of herbage infective larvae.