Table 3 Number of ESBL/ AmpC Escherichia coli (EEC) challenge organisms (mean log₁₀ cfu/g of 4 birds) in caecal contents of broiler chickens pre-treated with a competitive exclusion (CE) culture on day 1 of life or untreated controls exposed to seeder birds infected with EEC 1475 N (CTX-M-15) or EEC 1476 N (TEM 20) at 2 days of life (5 contact birds/ 1 seeder bird) (experiment 3)

1

20 contact birds pre-treated with a CE culture

20 contact birds untreated

20 contact birds pre-treated with a CE culture

20 contact birds untreated

2

Addition of 4 seeder birds infected with EEC 1475 N (10⁵ cfu/ bird)

Addition of 4 seeder birds infected with EEC 1475 N (10⁵ cfu/ bird)

Addition of 4 seeder birds infected with EEC 1476 N (10⁵ cfu/ bird)

Addition of 4 seeder birds infected with EEC 1476 N (10⁵ cfu/ bird)

Caecal contents

Caecal contents

Caecal contents

Caecal contents

9

2.8^a

7.2

5.6^b

8.6

16

5.3^a

7.9

6.6^b

9.1

23

6.1

7.3

6.8^b

8.5

30

5.9^a

7.6

6.1^b

7.8

37

3.7^a

6.1

5.7^b

7.8