Figure 2.

Community carriage of tetO (A) and tetW (B) in feces from beef cattle administered chlortetracycline and sulfamethazine (AS700) or no antibiotics in feed, and housed in a beef cattle confined feeding operation for 32 weeks (i.e., as a percentage of total bacteria). After 28 weeks, administration of AS700 ceased for 4 weeks to meet mandatory withdrawal requirements. Vertical lines with histogram bars represent standard errors of the mean (n = 5). AS700 treatment histogram bars indicated with an asterisk (*) differ (p < 0.050) from the control treatment at the corresponding sample time.