Purpose: The purpose was to determine differences in E. coli and Enterococcus spp. prevalence in commercial broiler chickens in conventional housing versus those housed at the Teaching Animal Unit (TAU) at NCSU.
Methods: Day-old chicks from the same hatchery and parent flock (hatched on the same day) were placed in an offsite conventional house (n=19,600; sister flock (SF)) and the TAU (n=4,000). Ceca (n=6) and spleen (n=6) were collected weekly from both systems until processing (eight weeks). A loop-full of macerated spleen and cecal contents were plated onto mEnterococcus and MacConkey agars for isolation of Enterococcus and E. coli, respectively. Presumptive positive isolates were selected phenotypically and speciated/confirmed using MALDI-TOF mass spectrometry. A maximum of eight isolates per sample were selected. Significance was determined using the student t-test (P<0.05).
Results: A total of 880 E. coli and 800 Enterococcus isolates were selected from all samples. Collectively, Enterococcus durans (25.8%) was observed more often than Enterococcus faecalis (20.8%), Enterococcus hirae (19.1%), and Enterococcus faecium (2.3%). Enterococcus prevalence was higher in ceca from TAU (46 of 48; 95.8%) versus SF (41 of 48; 85.4%). However, a significant difference (P< 0.04) was observed from the spleen of SF (5 of 48; 10.4%) versus TAU birds (1 of 48; 2%). Escherichia coli was recovered from all ceca (100%); no significant difference was observed in E.coli from spleen (TAU (12.5%); SF (14.5%)).
Significance: Differences in recovery of Enterococcus spp. from spleen versus ceca was unexpected and warrants further investigation. This observation may be useful for developing mitigation strategies.