Not long ago some articles featuring FDA’s suggestions for phasing out antibiotic use in meat animal production (though the headlines just said meat, which is woeful). Of course, a flurry of E-mails ensued between myself and many colleagues — looking for information that could support or refute some of the more questionable points being made. Anyway, this response came from Dr. Bill Henning, Professor Emeritus of Animal Science and Food Science at Penn State. He’s been faced with this challenge for years, it seems (comment was shared with Bill’s permission):
The THEORY is that long term feeding of antibiotics to livestock will cause pathogens to develop that have resistance to that antibiotic. The antibiotic resistant Salmonella is generally held up as an example. Most research shows this is not reproducible, but there are many forces pushing this. While very little antibiotic is used at low levels for growth promotion, there are some such as some tetracyclines (aureomycin especially) used to prevent illness in animals when they first arrive at a new facility after a long shipment or other high stress. Unfortunately, this will kill the use of some product like Rumensin (monensin) that have some antimicrobial properties and is fed to ruminants to change the flora in the rumen to enhance the production of proprionic acid (as compared to other volatile fatty acids) and improves the conversion of feed by about 10% (thus reducing manure and so-called green house gases). It is NOT used in human medicine but the industry is in danger of losing it and other such products. At one time, it was common to use antibiotics at low levels through the feeding phase of most poultry and swine. This is no longer the case. This whole issue has been around a long time. I attended a conference while in grad school at KY in about 1970 to address the question. The biological science still shows it is not a problem, but the political science has changed.
I am in favor of limiting use of antibiotics, but hate to have some anti-meat zealots making the rules.