RESUMEN
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]