Studies on parasitic worms of sheep in Scotland

Abstract

Laboratory studies on the embryonic and larval development of Haemonchus contortus under constant temperatures of 0·0°, 7·2°, 11°, 14·4°, 21·7° and 37° C., and varying moisture conditions were carried out. Reports of preliminary studies on Ostertagia spp., Trichostrongylus spp. and Oesophagostomum venulosum are included. Observations showed that eggs in the same culture may behave in several ways: (1) eggs may develop at different rates; (2) eggs may exhibit intermittent stages of active and inhibited development; and (3) eggs may fail to develop and die at any stage from unknown causes.