A wire-obstacle model has no effect on typical lesions and positive re-isolations after an infection with <i>Enterococcus cecorum</i> in SPF broilers

Enterococcus cecorum lesions include bacterial chondronecrosis with osteomyelitis (BCO) of the femur and free thoracic vertebrae (FTV). Mechanical stress can be applied using wire-obstacle models and has been suggested as a predisposing factor for BCO. Here, the effect of a wire-obstacle model was assessed following inoculation with E. cecorum.Two groups SPF broilers were orally inoculated at day of hatch with 107.6 colony-forming units of E. cecorum in peptone physiological saline (PPS) per bird. In one group, a wire-obstacle was placed between the feed and water. This obstacle had a 66% slope, a height of 30 cm and was covered with iron mesh. Additionally, two control groups, were inoculated with PPS, with an obstacle placed in one group. At 3, 7, 10, 14, 21, 28, 35 and 42 days post-inoculation, twenty birds from the E. cecorum-inoculated groups and eight birds from the PPS-inoculated groups were euthanized and macroscopically examined. Samples from spleen, femur and FTV were subjected to bacteriological examination.No significant differences in the number of birds with typical lesions or positive re-isolations were observed between the E. cecorum-inoculated groups with and without obstacle. Typical lesions were observed in 58 of the 320 inoculated birds, with pericarditis being the most common lesion (46 birds). Femoral BCO was observed in 7 birds. E. cecorum was re-isolated in 45 of the 320 inoculated birds and in none of the controls. A wire-obstacle model does not predispose for BCO in an E. cecorum model using SPF broilers.