Abstract
The effects of Eimeria ovinoidalis on the establishment of Escherichia coli K99+ Ent+ Nalr in the digestive tract were observed during the entire cycle of parasite development in nine gnotobiotic lambs. As compared to a saprophytic strain of autochthonous E.coli 35a from lamb colon and caecum which becomes established within 24 h, the development of a pathogenic allochthonous strain exhibited different profiles. Depending on the animal, the strain either did not become established or its development was retarded and then remained at an intermediate level (107/g), or was maximal (109-1010/g). In the first two cases, the mechanisms which inhibited or limited the development of E.coli K99+ in healthy animals were not effective when there was coccidia development.