The most obvious use for antibiotics in cattle is in treating illness. Vets administer them, along with other medicines, as needed to treat various bovine ailments. The feedlot lifestyle tends to encourage various common ailments as well as introducing new ones, so feedlot finished cattle tend to need more antibiotics. In fact, feedlot cattle are often fed a steady diet of antibiotics mixed with their food to help prevent illness before it occurs (Pollan, 2002).
A less obvious, but common use of antibiotics in beef production is to boost something ranchers refer to as “feed efficiency.” To put it simply, a steer with a regular intake of antibiotics, even when not ill in any way, will gain more muscle mass than a steer not given antibiotics but fed the same amount of food. Antibiotics used to boost feed efficiency or prevent disease are known as “sub-therapeutic antibiotics.”
Grain is expensive, and the value of beef cattle is found in the amount of meat on them. Thus, if a farmer can get more beef for his grain using cheap antibiotics, and come out ahead in the end, he has a strong financial incentive to do so.
70% of antibiotics and related drugs used in the United States are used in the agricultural production of livestock & poultry. According to FDA estimates, almost 29 million pounds of antibiotics were sold for use in food animals in 2009 (McKenna, 2010). In 2001 the Union of Concerned Scientists estimated that 24.6 million pounds of sub-therapeutic antibiotics were used (McKenna, 2010).
There is evidence that extensive antibiotic use in agriculture can lead to the development of antibiotic-resistant strains of bacteria (Union of Concerned Scientists). In 2006 Time Magazine reported that drug-resistant bacteria were “a factor in the deaths of more than 60,000 Americans each year” (Roosevelt, 2006).
McKenna, M. (2010, December 9). News break: FDA estimates US livestock get 29 million pounds of antibiotics per year. Retrieved October 14, 2011, from Wired.com: http://www.wired.com/wiredscience/2010/12/news-break-fda-estimate-us-livestock-get-29-million-pounds-of-antibiotics-per-year/
Pollan, M. (2002, March 31). Power Steer. Retrieved October 31, 2011, from Michael Pollan.com (previously published in NY Times Magazine): http://michaelpollan.com/articles-archive/power-steer/
Roosevelt, M. (2006, June 11). The Grass-Fed Revolution. Retrieved October 14, 2011, from Time.com: http://www.time.com/time/magazine/article/0,9171,1200759-2,00.html
Union of Concerned Scientists. (n.d.). Prescription for Trouble: Using Antibiotics to Fatten Livestock. Retrieved October 31, 2011, from Union of Concerned Scientists: http://www.ucsusa.org/food_and_agriculture/science_and_impacts/impacts_industrial_agriculture/prescription-for-trouble.html