Table 3.

Diversity of bacterial communities determined by 16S rRNA T-RFLP signal of litter from 5 sequential flocks of broiler chickens raised on commercial poultry farms. Two houses on each farm contained birds that were fed the AGP flavomycin or flavomycin + virginiamycin; two houses contained birds that were not fed antibiotics.

	No antibiotic		AGP
	Shannon Diversity Index	Richness	Shannon Diversity Index	Richness
Flock 1	3.94 ± 0.57	22.25 ± 4.6	4.11 ± 0.99	26.75 ± 13.1
Flock 2	3.68 ± 0.76	17.5 ± 8.3	3.76 ± 0.94	19.75 ± 13.3
Flock 3	3.85 ± 0.37	22.5 ± 6.4	3.66 ± 0.46	18.5 ± 3
Flock 4	3.42 ± 0.42	18 ± 5.6	3.38 ± 0.06	12.25 ± 8.73
Flock 5	3.27 ± 0.77	13.75 ± 6.2	3.83 ± 0.12	21.75 ± 6.8