1Department of Parasitology, College of Veterinary Medicine, Lorestan University, Lorestan, Khorramabad, Iran
2Department of Pathobiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3Department of Parasitology, Faculty of Specialized Sciences of Veterinary Medicine, Science and Research Campus, Islamic Azad University, Tehran, Iran
4Department of Parasitology, College of Veterinary Medicine, Lorestan University, Lorestan, Khorramabad, Iran;
Ten female lambs of 7-month-old were divided into two equal groups and raised under a helminth-free conditions. Animals in group 1 were immunized two times by whole gut homogenate (WGH) of Haemonchus contortus emulsified in Freund’s adjuvant. In group 2 (control), animals were injected by phosphate buffered saline emulsified in the same adjuvant. Animals were challenged by 10000 third-stage larvae (L3) of Haemonchus contortus on day 33 after the first immunization and then humanely killed on day 42. Animals were tested for serum antibody and eggs per gram of faeces (EPG) throughout the study and nematodes in their abomasom were counted after necropsy. The results indicated that animals immunized with WGH showed a higher level of serum antibodies. A significant difference was observed in mean optical density of sera in ELISA between the two groups (P<0.05) and a 77 and 78% reduction in EPG and nematode counts at necropsy, respectively (P<0.05).