Sub-therapeutic Antibiotics and Impacts on U.S. Hog Farms

Antimicrobial drugs are fed to hogs at sub-therapeutic levels to prevent disease and promote growth. However, there is concern that the presence of antimicrobial drugs in hog feed is a factor promoting the development of antimicrobial drug-resistant bacteria. This study describes the extent to which antibiotics are used in hog production and how this changed between 2004 and 2009. This study also uses a sample-selection model to examine the impact that use has on the productivity of U.S. hog operations. Using hog producer data from 2004, the analysis did not find a relationship between productivity and sub-therapeutic antibiotics fed during finishing, but productivity was significantly improved when fed to nursery pigs. These results are being evaluated using similar data from 2009. *The authors are with the U.S. Department of Agriculture, Economic Research Service. The views expressed herein are those of the authors and do not necessarily reflect the views or polices of the U.S. Department of Agriculture. Direct any correspondence to: [email protected] , (202) 694-5577. Sub-therapeutic Antibiotics and Impacts on U.S. Hog Farms Sub-therapeutic levels of antimicrobial drugs have been fed to hogs to prevent disease, promote growth, and improve overall animal health since the 1950‟s. A 1999 study by a National Academy of Sciences committee (National Research Council) concluded that most drugs and drug residues found in animal-derived foods posed a relatively low public risk so long as the drugs were used responsibly and according to label instructions. However, there has been concern that the presence of antimicrobial drugs in hog feed is a factor promoting development of antimicrobial drug-resistant bacteria. Since many of the drugs used to treat hogs are the same or similar to drugs used in human health care, the worry is that resistant organisms may pass from swine to humans through the handling of swine or their food products (Mathews). Concerns about antimicrobial drug-resistant bacteria prompted several European countries to ban the use of growth-promoting antimicrobial drugs in hog production as a precautionary measure. Sweden, Norway, Finland, and Denmark were among the first to impose bans (Hayes et al.). A European Union-wide ban on the use of antibiotics as growth promoters went into effect in 2006. Sub-therapeutic use of antimicrobial drugs for hog production in the U.S. has faced increasing scrutiny by public interest groups and the federal Food and Drug Administration. Some major U.S. food companies have announced that they will stop supplying consumers with livestock products that were raised using antibiotics for growth promotion (Hayes and Jensen; USA Today). Legislation has also been introduced to ban selected antibiotics (see Mathews for an overview of the scientific and legislative history).