Experimental study on the causative agents of hypobios is of Haemonchus contortus in sheep in Iran

Abstract

For determination the inducing factors of arrested development of 3th stage larvae of Haemonchus contortus as early L4 in sheep in 2 out of 4 climatic conditions of Iran, 24, six month old native sheep (shall breed) were randomly allocated into 3 equal groups I, II and III. Each sheep in each group received 10000 local isolate of H.contortus larvae not known to exhibit hypobiosis as follow: (i)Freshly collected larvae were given to group I, (control group).(ii)Larvae stored at 8- 10(oc) and 70% humidity for six weeks (simulating autumn climatic conditions of zone I) to group II.(iii)-larvae exposed to 30-350(oc) and 40% humidity for six weeks (simulating autumn climatic conditions of zone III) to group III. Two lambs in each group at 12, 21, 35 and 60 days post infection were necropsies and the number of adult and larvae were counted. Our findings suggest that the rate of arrested larvae in group II were statistically significant (p<0.01), whereas in two other groups only a very small number of larvae were subjected to hypobiosis. Meanwhile the number of adult worms recovered from group I receiving fresh larvae was higher than the other two groups.