Table 6.

Percentage reduction in the number of days of antimicrobial usage in E. coli–vaccinated birds in comparison to the control, not vaccinated, chickens at F1 and F2 recorded during experiment 1.

Farm	Cycle	Number of days of antimicrobial usage in not-vaccinated birds	Number of days of antimicrobial usage in E. coli–vaccinated birds	Percent reduction in the number of days of antimicrobial usage in K1
F1	1	19	14	−26.32
	2	20	16	−20%
	3	13	15	+15.38%1
	Average	17.33	15	−10.31
F2	1	11	8	−27.27%
	2	14	7	−50%
	3	9	5	−44.44%
	Average	11.33	6.67	−40.57

Abbreviation: E. coli, Escherichia coli.

¹In production cycle number 3 at F1 an incident of hip joints inflammation associated with Enterococcus spp. infection occurred in E. coli–vaccinated birds, which resulted in higher antimicrobial usage.