Parasitic gastro-enteritis of cattle: the effect of age on the infectivity of strongyle larvae

Abstract

Experiments were carried out to determine whether aged infective larvae of the cattle strongyles Haemonchus placei, Cooperia punctata, C. pectinata, and Oesophagostomum radiatum were still able to complete their parasitic life cycle. Mature adult parasites were obtained in calves, reared worm-free, following the ingestion of larvae of H. placei stored on moist filter paper for 150 days or of larvae of Cooperia spp. and O. radiatum kept in water for a similar period of time. Some larvae of all species developed to adults after 182 days' exposure on pasture. Many larvae of O. radiatum survived under these conditions; but only very few of H. placei.