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Parasitic Gastroenteritis (view source)
Revision as of 16:21, 26 December 2008
, 16:21, 26 December 2008→Rate of Infection
*stock ingest remaining overwintered L3
*stock ingest remaining overwintered L3
*strongyle eggs passed out with faeces onto pasture
*strongyle eggs passed out with faeces onto pasture
c) ''Development from egg to L3'':
*strongyle eggs passed in host faeces for most of the grazing season
*development of egg to L3 depends on dung-pat microclimate and requires:
**'''high relative humidity''' (nearly 100%) - dungpat acts as a "buffer" against drought; and
**'''warmth''' (optimum temperature 25°C) - dungpat cannot buffer against changes in macroclimate temperature.
*development is therefore influenced largely by '''macroclimate''' and '''temperature'''. Net result = concertina effect.
d) ''Translation of infective larvae''
*movement of larvae from dungpat onto grass in order to infect final host
*L3 must cross a zone of repugnance around the dungpat (up to 45cm) - normally left ungrazed
*L3 cross zone by swimming in a film of moisture. Also, beetle and earthworm activity, rain splash, soil migration, etc.