FIG. 1.

Schematic representation of the timeline of the experiment. Day numbers are shown within dietary feeding regimen. Animals were fed a silage-based diet and were then transitioned to, and maintained on, a grain-based diet. Gray regions indicate periods during which antibiotics were top dressed onto feed in the trough. Periodic dark rectangles indicate sampling dates, upon which two fecal swabs were obtained from each of the 300 steers.