Table 1.
Date, age of parent flock (weeks), day (0 or 5), and dose (non-inoculated, or 0.5 mL of 101 or 102 cfu/mL) of challenge and intervention (none (-), CEP, or SYN) for experiments 1 (n = 70 broilers), 2 (n = 70 broilers), and 3 (n = 80 broilers).
| Experiment | 1 | 2 | 3 | |||
|---|---|---|---|---|---|---|
| Date | 12 April–3 May 2017 | 24 May–14 June 2017 | 23 Oct–13 Nov 2017 | |||
| Parent flock1 | A, 54 wk | A, 60 wk | B, 57 wk | |||
| Day of challenge2 | Day 0 | Day 5 | Day 5 | |||
| Isolator | Challenge (cfu/mL)3 | Intervention4 | Challenge (cfu/mL)3 | Intervention4 | Challenge (cfu/mL)3 | Intervention4 |
| 1 | Non-inoculated (-) | - | Non-inoculated (saline solution) | - | Non-inoculated (saline solution) | - |
| 2 | 101 | None (-) | 101 | None (-) | 102 | None (-) |
| 3 | 101 | CEP | 101 | CEP | 102 | CEP |
| 4 | 101 | CEP | 101 | CEP | 102 | CEP |
| 5 | 102 | None (-) | 102 | None (-) | 102 | SYN |
| 6 | 102 | CEP | 102 | CEP | 102 | SYN |
| 7 | 102 | CEP | 102 | CEP | 102 | SYN |
| 8 | 102 | SYN | ||||
Abbreviations: CEP, competitive exclusion product; SYN, selection of pre- and probiotics.
In all 3 experiments, the eggs were disinfected with formaldehyde before incubation and in the hatcher before hatching.
Challenge with Escherichia coli E38.27 with blaCTX-M-1 on IncI1 plasmid.
Inoculated birds (n = 5 out of 10 in each isolator) received 0.5 mL of the mentioned challenge dose.
Intervention was implemented in all experiments from day 0, 4:00 pm until day 14, 4:00 pm. In experiment 1, supply of the intervention started immediately after challenge.