Experimentally induced foot rot in feedlot cattle fed rations containing organic iodine (ethylenediamine dihydriodide) and urea.

Foot rot was experimentally induced in feedlot cattle with a mixed inoculum of Fusobacterium necrophorum (Sphaerophorus necrophus) and Bacteroides melaninogenicus. Both bacteria were isolated from the lesions. Isolates of F necrophorum from 2 of the lesions were serologically compared, using a passive hemagglutination test with the strain used to induce the lesions. These isolates were serologically similar but not identical, indicating antigenic change had occurred during animal passage. The addition of ethylenediamine dihydriodide or urea to the rations did not affect the frequency of experimentally induced foot rot.