While few beef/cow-calf operations use antibiotics for production purposes, they were fed to an estimated 49 percent of cattle at large-scale feedlots in 2011, according to the study. In both 1994 and 2011, more than three-quarters of feedlots with at least 1,000 head provided antibiotics in feed or water, where the purpose is often growth promotion.
The share of finishing hogs sold or removed from operations administering antibiotics to promote growth fell from 52 percent to 40 percent between 2004 and 2009, the study concluded. The share from operations stating they did not know or did not report whether antibiotics were administered for growth promotion rose from 7 percent to 22 percent. The share of nursery hogs sold or removed from operations administering antibiotics for growth fell from 29 to 23 percent over 2004-2009, and the share from operations stating that they did not know or report whether antibiotics were administered rose from 5 to 20 percent, the study stated.
The share of broilers raised without antibiotics, except for disease treatment, rose from 44 percent to 48 percent between 2006 and 2011. The percentage of birds removed from operations reporting they did not know whether their birds were raised without antibiotics, except for disease treatment, rose from 29 percent to 32 percent, according to the study.