MOISTURE AND TEMPERATURE REQUIREMENTS IN FECES FOR THE DEVELOPMENT OFFREE-LIVING STAGES OF GASTROINTESTINAL NEMATODES OF SHEEP, CATTLE ANDDEER

Isolates from eight gastrointestinal nematode species parasitic in she ep, cattle and deer were maintained in sheep, to provide eggs in simil ar faecal environments and to compare temperature and moisture require ments for their development. Faecal cultures were processed at differe nt temperatures (for four species) and moisture contents (for the eigh t species). At 60% of faecal moisture content (FMC), maximal rates of development (expressed as L3/100 hatchable eggs estimated by an extrac tion technique from the faeces) were observed at 20, 23 and 28 degrees C respectively for Ostertagia Ieptospicularis, O. ostertagi, Teladors agia circumcincta and Trichostrongylus colubriforms. For the eight spe cies, the curves of development rates as functions of FMC were Gaussia n, without modification between 18 and 28 degrees C. Optimal developme nts were when the FMC ranged from 57 to 68%; low developments of 1L3/1 00eggs were observed when the FMC ranged from 85 to 95% and from 25 to 55%. The main differences between species were in the ability of the eggs of Teladorsagia circumcincta, Trichostrongylus colubriformis, T. vitrinus and Chabertia ovina to develop at lower FMC than Haemonchus c ontortus, O. ostertagi, O. leptospicularis and Cooperia oncophora.