Figure 2.

Comparisons of microbial richness (observed OTUs) and evenness (Shannon index) between the control group (top) and the combined treatment group (bottom) by sampling days. The low and high dose groups were collapsed together into a single treatment group to assess the effects of sampling days on microbial diversities. The difference among sampling days was insignificant in control (p > 0.05), but it was significant in the treatment group (p < 0.05). All calves were inoculated with laboratory strains of C. jejuni on day 5; the BRD groups were challenged with M. hemolytica on day 13; and the treatment groups were administered enrofloxacin on day 21.