Table 2.

E. coli counts in cecal samples on days 17 and 38 of the trial on MacConkey medium without and with antibiotic supplementation, shown as log₁₀ MPN/g values and standard deviations (± SD); 24 positive samples.

Antibiotic	Day	NC	CC	AB	FA	SA
None	17	6.83 ± 1.36	6.78 ± 1.14	7.83 ± 1.01	6.66 ± 1.70	6.27 ± 1.19
	38	6.04 ± 1.35	5.57 ± 1.47	5.23 ± 1.54	4.96 ± 1.2	4.46 ± 1.72
Ampicillin, cephalexin	17	0 (0/24)	0.97 ± 1.21 (16/24)	1.86 ± 0.31 (14/24)	1.66 ± 0.99 (16/24)	1.77 ± 1.18 (14/24)
and nalidixic acid	38	0.68 ± 0.53 (5/24)	1.38 ± 1.24 (11/24)	1.14 ± 1.28 (9/24)	1.46 ± 1.17 (16/24)	1.54 ± 1.38 (15/24)

NC, negative control without E. coli challenge; CC, E. coli challenge control; AB, ampicillin; FA, feed additive based on organic acids; SA, multistrain synbiotic.