Antibiotic use in livestock
Antibiotic use in livestock is the use of antibiotics for any purpose in the husbandry of livestock, which includes not only the treatment or prophylaxis of infection but also the use of subtherapeutic doses in animal feed to promote growth and improve feed efficiency in contemporary intensive animal farming. Antimicrobials (including antibiotics and antifungals) and other drugs are used by veterinarians and livestock owners to increase the size of livestock, poultry, and other farmed animals. The use of some drugs is banned in some countries due to food contamination or concern about increasing antibiotic resistance and what some consider antibiotic misuse. Other drugs may be used only under strict limits, and some organizations and authorities seek to further restrict the use of some or all drugs in animals . Other authorities, particularly those in animal industry, food animal medicine, and pharmacology industry, say that concerns for bacterial resistance in humans is overblown and restricting the availability of medicine is detrimental to animal health and the economical production of food.
- 1 History of the practice
- 2 Drugs and growth stimulation
- 3 Use in different livestock
- 4 Regulatory context
- 5 How drugs are given
- 6 When drugs are given
- 7 Use by country
- 8 Concerns about antibiotic resistance
- 8.1 Positions of advocates for restricting antibiotic use
- 8.2 Moderate positions
- 8.3 Positions of advocates for status quo
- 8.4 Effects of restricting antibiotic use
- 8.5 Difficulties with determining relevant facts
- 8.6 Specific resistance that has been identified
- 8.7 Mechanisms for transfer to humans
- 8.8 Action and advocacy by country
- 9 References
- 10 External links
History of the practice
In 1910 in the United States, a meat shortage resulted in protests and boycotts. After this and other shortages, the public demanded government research into stabilization of food supplies. Since the 1900s, livestock production on United States farms has had to rear larger quantities of animals over a short period of time to meet new consumer demands. Along with the new large animal densities came the threat of disease, therefore requiring a greater disease control of these animals. In 1950, a group of United States scientists found that adding antibiotics to animal feed increases the growth rate of livestock. American Cyanamid published research establishing the practice.
By 2001 this practice had grown so much that a report by the Union of Concerned Scientists found that nearly 90% of the total use of antimicrobials in the United States was for non-therapeutic purposes in agricultural production.
Drugs and growth stimulation
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Certain antibiotics, when given in low, sub-therapeutic doses, are known to improve feed conversion efficiency (more output, such as muscle or milk, for a given amount of feed) and/or may promote greater growth, most likely by affecting gut flora.
|Antibiotic Growth Promoters used in Livestock Production|
|Bambermycin||increase feed conversion ratio; growth promotion in poultry and cattle|
|Lasalocid||Ionophore||increase feed conversion ratio|
|Monensin||Ionophore||increase feed conversion ratio; increase weight gain in cattle and sheep|
|Salinomycin||Ionophore||increase feed conversion ratio; increase weight gain|
|Virginiamycin||peptide||promotes growth of poultry|
|Bacitracin||peptide||promotes growth of poultry|
Use in different livestock
In swine production
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The use of antibiotics to increase the growth of pigs is most studied of all livestock.
In production of other livestock
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The use of drugs in food animals is regulated in nearly all countries. Historically, this has been to prevent alteration or contamination of meat, milk, eggs and other products with toxins that are harmful to humans. Treating a sick animal with drugs may lead to some of those drugs remaining in the animal when it is slaughtered or milked. Scientific experiments provide data that shows how long a drug is present in the body of an animal and what the animal's body does to the drug. Of particular concern are drugs that may be passed into milk or eggs. By the use of 'drug withdrawal periods' before slaughter or the use of milk or eggs from treated animals, veterinarians and animal owners ensure that the meat, milk and eggs is free of contamination.
These restrictions include not only poisons or drugs (such as penicillin) which may result in allergic reactions but also contaminants which may cause cancer. It is illegal in the USA to administer drugs or feed substances to animals if they have been shown to cause cancer.
One of the main restrictions is the amount that is administered to animals in the industry. These drugs should be administered to healthy livestock at a low concentration of 200 g per ton of feed. The amount distributed is also altered throughout the lifespan of livestock in order to meet specific growth needs.
Legality of the use of specific drugs in animal medicine varies according to location.
Just as in human medicine, some drugs are available over the counter and others are restricted to use only on the prescription of a veterinary physician. In the USA, the Food and Drug Administration (FDA) requires specific labels on all drugs, giving directions on the use of the drug. For animals, this includes the species, dose, reason for giving the drug (indication) and the required withdrawal period, if any. Federal law requires laypersons to use drugs only in the manner listed. Veterinarians who have examined an animal or a herd of animals may issue a replacement label, giving new directions, based on their medical knowledge. It is illegal in the USA for any layperson to administer any drug to a food animal in a way not specific to the drug label. Over-the-counter drugs which may be used by laypersons include anti-parasite drugs (including fly sprays) and antimicrobials. These drugs can be applied as sprays, creams, injections, oral pills or fluids, or as a feed additive, depending on the drug and the label.
In December 2013, the FDA updated its regulations to try to begin reducing use of antibiotics for growth enhancement. Significant lobbying comes from all directions, from those against tighter regulation to those who complain it doesn't go far enough.
Nearly all hormones and painkillers are illegal for laypersons to use in food animals. Additionally, there are very few drugs labelled for use in laying hens, ducks, goats, meat rabbits, or other minor species.
If a layperson gives a drug to a food animal, they are responsible for ensuring that an adequate withdrawal period is allowed to ensure that the meat or milk is not contaminated.
For drugs that can not be legally given by lay persons, or if the animal or herd does not respond to treatment, a veterinary physician may prescribe a different drug or one at a different dose than is on the label. The veterinarian will also give directions as to the appropriate withdrawal period.
How drugs are given
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Drugs can be administered to animals in a variety of means, just as with humans. Among these are topical (on the skin), by injection (including intravenous, subcutaneous, subcutaneous implants, intramuscular and intraperitonial), and orally. Oral drugs can be in pill or liquid form, or can be given by mixing with feed or water. The appropriate route for treatment depends on the specific case and can vary by: illness, severity of illness, selected drug, age or condition of the animal, species of the animal, type of housing and other factors. For animals that are not regularly fed a concentrated feed or which can be handled repeatedly, a slow-release injection might be the most appropriate. Some drugs are not available or appropriate in this form and should be delivered orally. For animals that are fed regularly (rather than grazing freely) or that can not be easily handled, the most appropriate means of administering the drug may be to include the drug in feed or water. This eliminates the stress of daily (or more frequent) handling of animals, which can make the animals more ill. Poultry are most commonly medicated in this fashion, as they are easily stressed to the point of dying. Administering the drug by feed also prevents injection wounds in animals.
When drugs are given
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The timely administration of drugs is key to preventing animal suffering and economic loss to the farmer. Animals which are ill can infect other animals, and may become so ill that they can not be sold. A variety of techniques are used to monitor animals for illness so that they can be treated appropriately. Stress reduction, adequate nutrition, shelter, and quarantine of incoming stock are all important factors to promote growth and reduce illness and the need for active treatment. The age and status of an animal is also important in determining correct treatment - a young animal or pregnant animal is at greater risk and are treated more aggressively than an older animal.
One complicating factor for treating illnesses in animals is the difficulty in catching a disease before a large number of animals are infected. In many significant diseases, the animal may be infectious for several days before showing signs of the illness. Others may be carriers of the disease but do not actually show illness themselves. In these cases, a flock or herd of animals may have a mix of sick animals, completely well animals, and animals which are infected but are not yet showing signs. In these cases, attempting to separate the ill animals would be of little help, as the extra stress would only serve to make the situation worse. In these cases, treating the entire group would result in the most rapid recovery of the sick animals with the least amount of suffering and death.
Use by country
Although the European Union banned the use of antibiotics as growth agent in 2006, its use has not changed much until recently. In Germany, 1,734 tons of antimicrobial agents were used for animals in 2011 compared with 800 tons for humans. On the other hand, Sweden banned their use in 1986 and Denmark started cutting down drastically in 1994, so that its use is now 60% less. In the Netherlands, the use of antibiotics to treat diseases increased after the ban on its use for growth purposes in 2006. In 2011, the EU voted to ban the prophylactic use of antibiotics, alarmed at signs that the overuse of antibiotics is blunting their use for humans.
In 1952, 2 million pounds of antibiotics were produced, by 1998 at least 50 million pounds were produced, about half of which was used for human treatment and about forty percent of which was used in animals, the "lion's share" of which was mixed into feed to promote growth. in 2011 80% of antibiotics went to livestock production.
Of all countries, China produces and consumes the most antibiotics.
Half of the antibiotics manufactured in China are used in the production of livestock.
In 2012 India manufactured about a third of the total amount of antibiotics in the world.
Brazil is the world's largest exporter of beef and the government regulates antibiotic use in the cattle production industry.
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Concerns about antibiotic resistance
More recently, there has been increased concern about the use of anti-microbials in animals (including pets, livestock, and companion animals) contributing to the rise in antibiotic resistant infections in humans. The use of antimicrobials has been linked to the rise of resistance in every drug and species where it has been studied, including humans and livestock. However, the role of antibiotic use in food animals - in contrast to the use of antibiotics in humans - in the rise of resistant infections in humans is in dispute. The use of antimicrobials in various forms is widespread throughout animal industry, and is presented as key to preventing animal suffering and economic loss. It is linked by some activist groups to animal welfare concern, large scale commercial agriculture, international food trade, agricultural protectionist laws, environmental protection (including climate change) and other topics, which make the aims of some groups on both sides of the debate difficult to untangle.
Positions of advocates for restricting antibiotic use
The practice of using antibiotics for growth stimulation is problematic for these reasons:
- it is the largest use of antimicrobials worldwide
- subtherapeutic use of antibiotics results in bacterial resistance
- every important class of antibiotics are being used in this way, making every class less effective
- the bacteria being changed harm humans
Donald Kennedy, former director of the United States Food and Drug Administration, has said "There's no question that routinely administering non-therapeutic doses of antibiotics to food animals contributes to antibiotic resistance." David Aaron Kessler, another former director of the FDA, said that "We have more than enough scientific evidence to justify curbing the rampant use of antibiotics for livestock, yet the food and drug industries are not only fighting proposed legislation to reduce these practices, they also oppose collecting the data."
Some scientists have said that "all therapeutic antimicrobial agents should be available only by prescription for human and veterinary use."
The Pew Charitable Trusts have stated that "hundreds of scientific studies conducted over four decades demonstrate that feeding low doses of antibiotics to livestock breeds antibiotic-resistant superbugs that can infect people. The FDA, the U.S. Department of Agriculture and the Centers for Disease Control and Prevention all testified before Congress that there is a definitive link between the routine, non-therapeutic use of antibiotics in food animal production and the challenge of antibiotic resistance in humans."
Positions of advocates for status quo
In 2011 the National Pork Producers Council, an American trade association, has said "Not only is there no scientific study linking antibiotic use in food animals to antibiotic resistance in humans, as the U.S. pork industry has continually pointed out, but there isn't even adequate data to conduct a study." The statement contradicts scientific consensus, and was issued in response to a United States Government Accountability Office report that asserts "antibiotic use in food animals contributes to the emergence of resistant bacteria that may affect humans".
Effects of restricting antibiotic use
When government regulation restricts use of antibiotics the negative economic impact is not often considered.
Difficulties with determining relevant facts
It is difficult to set up a comprehensive surveillance system for measuring rates of change in antibiotic resistance. The US Government Accountability Office published a report in 2011 stating that government and commercial agencies had not been collecting sufficient data to make a decision about best practices.
Specific resistance that has been identified
In the late 1980s doctors in Europe first reported that certain bacteria were becoming resistant to vancomycin. They began to study whether there was a connection between resistance and the practice of feeding a drug related to vancomycin to animals as a growth stimulant. Vancomycin-resistant enterococci can spread from animals to humans.
Mechanisms for transfer to humans
When manure from antibiotic-fed swine is used as fertilizer elsewhere, the manure may be contaminated with bacteria which can infect humans.
Action and advocacy by country
Legislation and activism worldwide have aimed at restricting antibiotic use in livestock.
Some grocery stores have policies about voluntarily not selling meat produced by using antibiotics to stimulate growth. In 2012 in the United States advocacy organization Consumers Union organized a petition asking the store Trader Joe's to discontinue the sale of meat produced with antibiotics.
Some proposed legislation in the US has failed to be adopted. The Animal Drug and Animal Generic Drug User Fee Reauthorization Act of 2013 proposes other regulation.
In the United States the danger of emergence of antibiotic-resistant bacterial strains due to wide use of antibiotics to promote weight gain in livestock was determined by the United States Food and Drug Administration in 1977, but nothing effective was done to prevent the practice. In March, 2012 the United States District Court for the Southern District of New York, ruling in an action brought by the Natural Resources Defense Council and others, ordered the FDA to revoke approvals for the use of antibiotics in livestock which violated FDA regulations. On 11 April 2012 the FDA announced a program to phase out unsupervised use of drugs as feed additives and, on a voluntary basis, convert approved uses for antibiotics to therapeutic use only, requiring veterinarian supervision of their use and a prescription.
In 2012 an American newspaper described the Chinese government's regulation of antibiotics in livestock production as "weak".
In 2011 the Indian government proposed a "National policy for containment of antimicrobial resistance". Other policies set schedules for requiring that food producing animals not be given antibiotics for a certain amount of time before their food goes to market.
Antibiotic resistant bacteria have been found in Brazilian cattle.
In 1998 some researchers reported use in livestock production was a factor in the high prevalence of antibiotic resistant bacteria in Korea. In 2007 The Korea Times noted that Korea has relatively high usage of antibiotics in livestock production. In 2011 the Korean government banned the use of antibiotics as growth promoters in livestock.
In 1999 the New Zealand government issued a statement that they would not then ban the use of antibiotics in livestock production. In 2007 ABC Online reported on antibiotic use in chicken production in New Zealand.
- Ogle, Maureen (3 September 2013). "Riots, Rage and Resistance: A Brief History of How Antibiotics Arrived on the Farm". Scientific American. Retrieved 5 November 2013. This reference should be replaced with citations to a book later published by the same author
- Reported locally in these:
- "To Become Vegetarians", Mansfield (O.) News, January 17, 1910, p2
- "150,000 at Cleveland Stop the Use of Meat" Syracuse Herald-Journal, January 25, 1910, p1
- "Boycott on Meat is Rapidly Spreading; Men Who Are Blamed For High Price", Atlanta Constitution, January 25, 1910, p1
- Ogle cites To meet this new consumer demand for animal meat, the improved health management has since introduced about seventeen classes of antimicrobial drugs is approved for use in food animals in the United States today.
- "They've Doubled Gains With New Drugs". Successful Farming 48 (6): 45. June 1950.
- "Antibiotics Now Proved in Hog and Poultry Ratios, They're the Biggest Feeding News in 40 Years!". Successful Farming 49 (3): 33. March 1951.
- "Hogging It!: Estimates of Antimicrobial Abuse in Livestock". Union of Concerned Scientists. 2001.
- Christopher D. Reinhardt, MS, PhD, Last full review/revision March 2012 Merck Veterinary Manual: Antimicrobial Feed Additives
- Reinhardt, Christopher D. (2012), "Antimicrobial Feed Additives", in Aiello, Susan E.; Moses, Michael A., Merck Veterinary Manual, Merck & Co. and Merial, retrieved 4 November 2013
- Graham, JP; Boland, JJ; Silbergeld, E (Jan–Feb 2007). "Growth promoting antibiotics in food animal production: an economic analysis.". Public health reports (Washington, D.C. : 1974) 122 (1): 79–87. PMID 17236612.
- Dennis, Brady (2013-12-11), "FDA finalizes voluntary rules on phasing out certain antibiotics in livestock", Washington Post.
- Plumer, Brad (2013-12-14), "The FDA is cracking down on antibiotics at farms. Here's what you should know.", Washington Post.
- Koch, Julia (20 Nov 2013). "Cutting Antibiotics: Denmark Leads Way in Healthier Pig Farming". Spiegel Online International. Retrieved 2014-05-22.
- Cogliani,, Carol; Goossens, Herman; Christina Greko (2011). "Restricting Antimicrobial Use in Food Animals: Lessons from Europe". Microbe Magazine. Retrieved 2014-05-22.
- Gilbert, Natasha (10 Jan 2012). "Rules tighten on use of antibiotics on farms". Nature.
- Levy, Stuart B. (March 1998). "The Challenge of Antibiotic Resistance". Scientific American: 46–53. Retrieved 26 August 2013.
- Philpott, Tom (29 July 2011). "What the USDA Doesn't Want You to Know About Antibiotics and Factory Farms | Mother Jones". motherjones.com. Retrieved 27 August 2013.
- Tatlow, Didi Kirsten (18 February 2013). "Global Health Threat Seen in Overuse of Antibiotics on Chinese Pig Farms". rendezvous.blogs.nytimes.com. Retrieved 28 August 2013.
- Wei, R.; Ge, F.; Huang, S.; Chen, M.; Wang, R. (2011). "Occurrence of veterinary antibiotics in animal wastewater and surface water around farms in Jiangsu Province, China". Chemosphere 82 (10): 1408–1414. doi:10.1016/j.chemosphere.2010.11.067. PMID 21159362.
- Hu, X.; Zhou, Q.; Luo, Y. (2010). "Occurrence and source analysis of typical veterinary antibiotics in manure, soil, vegetables and groundwater from organic vegetable bases, northern China". Environmental Pollution 158 (9): 2992–2998. doi:10.1016/j.envpol.2010.05.023. PMID 20580472.
- Zhao, L.; Dong, Y. H.; Wang, H. (2010). "Residues of veterinary antibiotics in manures from feedlot livestock in eight provinces of China". Science of the Total Environment 408 (5): 1069–1075. doi:10.1016/j.scitotenv.2009.11.014. PMID 19954821.
- Wu, Alex (12 January 2012). "Livestock in China Given Too Many Antibiotics". The Epoch Times. Retrieved 28 August 2013.
- Gale, Jason; Narayan, Adi (7 May 2012). "Drug-Defying Germs From India Speed Post-Antibiotic Era – Bloomberg". bloomberg.com. Retrieved 28 August 2013.
- Millen, D. D.; Pacheco, R. D. L.; Meyer, P. M.; Rodrigues, P. H. M.; De Beni Arrigoni, M. (2011). "Current outlook and future perspectives of beef production in Brazil". Animal Frontiers 1 (2): 46. doi:10.2527/af.2011-0017.
- Silbergeld, E. K.; Graham, J.; Price, L. B. (2008). "Industrial Food Animal Production, Antimicrobial Resistance, and Human Health". Annual Review of Public Health 29: 151–169. doi:10.1146/annurev.publhealth.29.020907.090904. PMID 18348709.
- McVeigh, Karen (19 September 2012). "Scientists: overuse of antibiotics in animal agriculture endangers humans". theguardian.com. Retrieved 26 August 2013.
- Kessler, David Aaron (27 March 2013). "Antibiotics and the Meat We Eat". The New York Times (New York City: NYTC). ISSN 0362-4331. Retrieved 26 August 2013.
- Gilchrist, M. J.; Greko, C.; Wallinga, D. B.; Beran, G. W.; Riley, D. G.; Thorne, P. S. (2006). "The Potential Role of Concentrated Animal Feeding Operations in Infectious Disease Epidemics and Antibiotic Resistance". Environmental Health Perspectives 115 (2): 313–316. doi:10.1289/ehp.8837. PMC 1817683. PMID 17384785.
- The Pew Charitable Trusts (15 October 2012). "Pew Comments on Proposed Antibiotics Legislation". pewtrusts.org. Retrieved 26 August 2013.
- de La Hamaide, Sybille (11 January 2012). "Antibiotics for livestock vital to feed world: OIE | Reuters". reuters.com. Retrieved 28 August 2013.
- National Pork Producers Council (15 September 2011). "Nat'l Pork Producers Council Issues Statement About GAO's Report on Antibiotic Resistance". growinggeorgia.com. Retrieved 29 August 2013.
- Philpott, Tom (21 September 2011). "Meat Industry Still Denying Antibiotic Resistance". motherjones.com. Retrieved 29 August 2013.
- The Pew Charitable Trusts. http://www.pewhealth.org/uploadedFiles/PHG/Content_Level_Pages/Issue_Briefs/HHIFBibliographyFinal%20with%20TOC%20_071712.pdf. Missing or empty
- United States Government Accountability Office (7 September 2011). http://www.gao.gov/products/GAO-11-801. "Antibiotics have saved millions of lives, but antibiotic use in food animals contributes to the emergence of resistant bacteria that may affect humans." Missing or empty
- Couric, Katie (10 February 2010). "Animal Antibiotic Overuse Hurting Humans?". CBS News. New York City: CBS. Retrieved 29 August 2013.
- Phillips, I.; Casewell, M.; Cox, T.; De Groot, B.; Friis, C.; Jones, R.; Nightingale, C.; Preston, R.; Waddell, J. (2003). "Does the use of antibiotics in food animals pose a risk to human health? A critical review of published data". Journal of Antimicrobial Chemotherapy 53 (1): 28–52. doi:10.1093/jac/dkg483. PMID 14657094.
- Yukhananov, Anna (11 April 2012). "U.S. seeks voluntary antibiotic limits in livestock". reuters.com. Retrieved 28 August 2013.
- Bax, R.; Bywater, R.; Cornaglia, G.; Goossens, H.; Hunter, P.; Isham, V.; Jarlier, V.; Jones, R.; Phillips, I.; Sahm, D.; Senn, S.; Struelens, M.; Taylor, D.; White, A. (2001). "Surveillance of antimicrobial resistance-what, how and whither?". Clinical Microbiology and Infection 7 (6): 316–325. doi:10.1046/j.1198-743x.2001.00239.x. PMID 11442565.
- Government Accountability Office (7 September 2011), "Antibiotic Resistance: Agencies Have Made Limited Progress Addressing Antibiotic Use in Animals", gao.gov, retrieved 27 August 2013
- Baragona, Steve (12 May 2010). "Use of Antibiotics in Livestock Debated". voanews.com. Retrieved 29 August 2013.
- Wegener, H. C. (2003). "Antibiotics in animal feed and their role in resistance development". Current Opinion in Microbiology 6 (5): 439–445. doi:10.1016/j.mib.2003.09.009. PMID 14572534.
- Knox, Richard (21 February 2012). "How Using Antibiotics in Animal Feed Creates Superbugs". npr.org. Retrieved 26 August 2013.
- Carlet, J.; Jarlier, V.; Harbarth, S.; Voss, A.; Goossens, H.; Pittet, D.; Participants of the 3rd World Healthcare-Associated Infections Forum (2012). "Ready for a world without antibiotics? The Pensières Antibiotic Resistance Call to Action". Antimicrobial Resistance and Infection Control 1 (1): 11. doi:10.1186/2047-2994-1-11. PMC 3436635. PMID 22958833.
- Vieira, A. R.; Collignon, P.; Aarestrup, F. M.; McEwen, S. A.; Hendriksen, R. S.; Hald, T.; Wegener, H. C. (2011). "Association Between Antimicrobial Resistance inEscherichia coliIsolates from Food Animals and Blood Stream Isolates from Humans in Europe: An Ecological Study". Foodborne Pathogens and Disease 8 (12): 1295–1301. doi:10.1089/fpd.2011.0950. PMID 21883007.
- Zhang, S. (2013). "Pig-manure fertilizer linked to human MRSA infections ". Nature. doi:10.1038/nature.2013.13752.
- European Commission (22 December 2005). "EUROPA – PRESS RELEASES – Press release – Ban on antibiotics as growth promoters in animal feed enters into effect". europa.eu. Retrieved 26 August 2013.
- "Meat Without Drugs". Consumers Union. Retrieved 27 August 2013., which is described in the following works
- Gore, Al (2013). "The Reinvention of Life and Death: Antibiotics before Swine". The Future : Six Drivers of Global Change (First edition. ed.). New York: Random House. pp. 227 and citation on 475. ISBN 9780812992946.
- Hurd, Scott (26 June 2012). "Commentary: 'Meat without Drugs' could be inhumane". Bovine Veterinarian. Retrieved 27 August 2013. "All peer-reviewed scientific risk assessments have demonstrated a negligible risk of human health harm due to livestock antibiotic use."
- Greenaway, Twilight (20 June 2012). "Your meat on drugs: Will grocery stores cut out antibiotics?". Grist. Retrieved 27 August 2013.
- Rogers, Laura (28 December 2012). "Laura Rogers: A New Year's Resolution: Put Animals on an Antibiotics Diet". huffingtonpost.com. Retrieved 26 August 2013.
- Wallinga, David (12 February 2013). "David Wallinga, M.D.: Animal Antibiotic Use Continues Upwards, FDA Keeps Blinders on". huffingtonpost.com. Retrieved 27 August 2013.
- Philpott, Tom (17 Sep 2010). "UPDATED: With the food safety bill dead, time for the FDA/USDA to grow some backbone". Grist. Retrieved 27 August 2013.
- John Gever (23 March 2012). "FDA Told to Move on Antibiotic Use in Livestock". MedPage Today. Retrieved 24 March 2012.
- Gardiner Harris (11 April 2012). "U.S. Tightens Rules on Antibiotics Use for Livestock". The New York Times. Retrieved 12 April 2012.
- "FDA's Strategy on Antimicrobial Resistance - Questions and Answers". U.S. Food and Drug Administration. 11 April 2012. Retrieved 12 April 2012. "“Judicious use” is using an antimicrobial drug appropriately and only when necessary; Based on a thorough review of the available scientific information, FDA recommends that use of medically important antimicrobial drugs in food-producing animals be limited to situations where the use of these drugs is necessary for ensuring animal health, and their use includes veterinary oversight or consultation. FDA believes that using medically important antimicrobial drugs to increase production in food-producing animals is not a judicious use."
- Salamon, Maureen (11 February 2013). "China's Overuse of Antibiotics in Livestock May Threaten Human Health". health.usnews.com. Retrieved 28 August 2013.
- Thacker, Teena (13 April 2011). "Govt wants to limit use of antibiotics in animals – Indian Express". indianexpress.com. Retrieved 28 August 2013.
- Sinha, Kounteya (25 November 2011). "New norm to curb antibiotic resistance – Times of India". indiatimes.com. Retrieved 28 August 2013.
- Sinha, Kounteya (6 April 2012). "In a first, antibiotics bar on food-producing animals – Times of India". indiatimes.com. Retrieved 28 August 2013.
- Pereira, M. S. V.; Siqueira-Júnior, J. P. (1995). "Antimicrobial drug resistance in Staphylococcus aureus isolated from cattle in Brazil". Letters in Applied Microbiology 20 (6): 391–395. doi:10.1111/j.1472-765X.1995.tb01328.x. PMID 7786507.
- Kim, Woo Joo; Park, Seung Chull (1998). "bacterial Resistance to Antimicrobial Agents: An Overview from Korea". Yonsei Medical Journal 39 (6): 488–494. Retrieved 29 August 2013.
- Won-sup, Yoon (25 June 2007). "Antibiotics in Livestock Harm Human Beings". The Korea Times. Retrieved 29 August 2013.
- Flynn, Dan (7 June 2011). "South Korea Bans Antibiotics in Animal Feed". foodsafetynews.com. Retrieved 29 August 2013.
- staff (7 January 1999). "NZ holds off ban on animal antibiotics – National – NZ Herald News". nzherald.co.nz. Retrieved 29 August 2013.
- Williams, Robyn; Cook, Greg (11 August 2007). "Antibiotics and intensive chicken farming in New Zealand – The Science Show". abc.net.au. Retrieved 29 August 2013.
- PBS report on antibiotics in livestock production
- Fix Food, Fix Antibiotics, a 90 second video explaining the problem of antibiotic resistance and campaigning for action
- 2011 FDA report on antibiotics in animals in the United States
- Pew Trust campaign for restricting antibiotic use
- Antibiotic Resistance and the Use of Antibiotics in Animal Agriculture: Hearing before the Subcommittee on Health of the Committee on Energy and Commerce, House of Representatives, One Hundred Eleventh Congress, Second Session, July 14, 2010