Differences in lesion development of slow- and fast-growing meat-type chickens after experimental challenge with Enterococcus cecorum

Field observations suggest genotype-associated differences in susceptibility to infection with Enterococcus cecorum (EC). We hypothesized that slow-growing (SG) chickens show less clinical signs and reduced lesions compared to fast-growing (FG) chickens after experimental challenge with EC. At 1-day post-hatch (dph), 97 FG and 97 SG chickens were randomly assigned to four groups: control, SG (CSG), control, FG (CFG), EC-inoculated, SG (ESG), and EC-inoculated, FG (EFG). After oral inoculation with 107 colony forming units EC or mock inoculation with physiological saline, chickens were monitored for clinical signs and samples were collected weekly for further analysis via ELISA, real-time PCR, and flow cytometric analysis. The final necropsy of 40 chickens per group was carried out at 43/44 dph. Clinical signs and pathological findings were observed in a reduced number of chickens in group ESG compared to EFG. Extra-intestinal colonization with EC at 43/44 dph was significantly reduced in group ESG compared to EFG (P P