Figure 2.

Whole blood bactericidal assay. Heparinized whole blood was collected from the wing vein of hens in conventional (CC, dashed column; A–D) and cage-free (CF; E–H) environment at early (white), peak (light gray), and late (dark gray) lay and pooled (n = 5 hens) within barn into CO2 independent media. The strains APEC O1 (A and E), APEC O2 (B and F), χ7122 (C and G), and MG1655 (D and H) were mixed with the whole blood solution. Values represent the average of data from 4 independent pools, assayed in triplicate. Statistical differences were calculated using one-way ANOVA and Tukey's test for multiple comparisons between maturity stages. ∗, P < 0.05. APEC, avian pathogenic Escherichia coli.