PBS writes that ranchers and farmers have been feeding antibiotics to the animals we eat ever since they discovered decades ago that just small doses of antibiotics administered daily would make most animals gain as much as 3 percent more weight than they otherwise would. Due to the fact that profits are measured in pennies per animal in this industry, such weight gain was revolutionary. Although it is still not completely clear why feeding small "sub-therapeutic" doses of antibiotics, like tetracycline, to animals makes them gain weight, there is some evidence which indicates that the antibiotics kill the flora that would normally thrive in the animals' intestines, thereby allowing the animals to utilize their food more effectively. In a news release on Feb. 11, 2013, Michigan State University reported, Unchecked antibiotic use in animals may affect global human health.
The increasing production and use of antibiotics, about half of which is used in animal production, has been mirrored by the increasing number of antibiotic resistance genes, or ARGs, effectively lowering antibiotics’ ability to fend off diseases, in animals and humans. China, which is the world’s largest producer and consumer of antibiotics, and many other countries, don’t monitor the powerful medicine’s usage or impact on the environment, according to a study in the current issue of the Proceedings of the National Academy of Sciences. James Tiedje, a Michigan State University professor, has said, on Chinese commercial pig farms, researchers discovered 149 unique ARGs, some at levels which were 192 to 28,000 times higher than the control samples.
Tiedje has commented, “Our research took place in China, but it reflects what’s happening in many places around the world. The World Organization for Animal Health and the U.S. Food and Drug Administration have been advocating for improved regulation of veterinary antibiotic use because those genes don’t stay local.” The use of antibiotics in China are weakly regulated, and the country uses four times more antibiotics for veterinary use than the United States uses. Becuase the medicine is poorly absorbed by animals, much of it ends up in manure, in an estimated 700 million tons annually from China alone. This manure is traditionally spread as fertilizer, sold as compost or ends up downstream in rivers or groundwater, which takes ARGs with them. The daily exposure to antibiotics,
such as those seen in animal feed, allows microbes carrying ARGs to thrive.
The ARGs can reach the general population via food crops, drinking water and interactions with farm workers. Tiedje has said, due to this undesirable cycle, ARGs pose a potential global risk to human health and should be classified as pollutants. It is important to protect the effectiveness of our current antibiotics because discovering new ones is very difficult. The development of multidrug resistance is a global problem and must be addressed in a comprehensive manner. An area that needs to be addressed is more judicious use and management of wastes which contain ARGs.