Lesion scores of broiler chickens immunized with clostridial proteins. Chickens were immunized subcutaneously with the indicated vaccines on days 7 and 17, challenged with C. perfringens, and the lesions scores assessed at day 28. The solid horizontal bars represent the average lesion score in each group. Intestinal lesions in the small intestine (duodenum to ileum) were scored as previously reported: 0, no gross lesions; 1, thin or friable walls; 2, focal necrosis or ulceration (1 to 5 foci); 3, focal necrosis or ulceration (6 to 15 foci); 4, focal necrosis or ulceration (16 or more foci); 5, patches of necrosis 2 to 3 cm long; 6, diffuse necrosis typical of field cases. (a) Birds were immunized and challenged orally with EHE-NE18 (days 24 and 25). (b) Birds were immunized and challenged in-feed with EHE-NE18 (days 26 and 27). (c) Birds were immunized and challenge in-feed with WER-NE36 (days 26 and 27). Error bars represent SEM.