Why and How Antibiotics Are Used in Swine Production

Abstract

In summary, published research data clearly show that the use of antibiotics during all phases of growth benefits the rate and efficiency of body weight gain, reduces mortality and morbidity, reduces subclinical disease, and improves health in pigs. Also, antibiotics at breeding and during lactation benefits reproductive and lactational performance in sows. The economic benefits are several-fold greater than the cost of the antibiotic when a cost-effective antibiotic is used for this purpose. Monitoring and surveillance of microbial resistance in animals and humans has continued, with no animal-to-human infection path being clearly delineated. Although the incidence of antibiotic resistance in the human population remains high, there is no clear evidence that the levels or patterns have changed. The high levels of antimicrobial resistance in humans likely result from antibiotics prescribed directly to humans, because well over half of the antibiotics produced in the United States is used in human medicine. Whether antibiotic usage in swine, poultry, and other food-producing animals contributes to antibiotic resistance in the human population will continue to be debated. Even though antibiotics have been fed for nearly 50 years to literally billions of animals, there is still no convincing evidence of unfavorable health effects in humans that can be directly linked to the feeding of subtherapeutic levels of antibiotics to swine or other animals. Hopefully, policy decisions in the future regarding the use of antimicrobials in animals will be based on science and sound risk assessment, and not on emotionalism.

Excretion masses and environmental occurrence of antibiotics in typical swine and dairy cattle farms in China

“…vulnerable to infectious diseases (Cromwell, 2002). For example, high concentrations of chlortetracycline, tetracycline, leucomycin and florfenicol were found in the feces and feeds samples for piglets (Table 1 and Table S7).…”

“…Antibiotics are used extensively in animals to treat, prevent microbial infections and promote growth (Cromwell, 2002;Gaskins et al, 2002;Kummerer, 2009;Sarmah et al, 2006). In China, 210,000 tons of antibiotics are produced every year, of which 48% is applied in agriculture and livestock industry .…”

Fate and transport of tylosin-resistant bacteria and macrolide resistance genes in artificially drained agricultural fields receiving swine manure

“…Research has documented the positive effects of antibiotics in swine feed at subtherapeutic levels in a variety of contexts, including: improvement of growth rates, increased feeding efficiencies, reduced mortality rates and heightened reproductive rates (Hays, 1977;CAST, 1981;Cromwell, 1991). These improvements coupled with declining prices has led to approximately 90% of starter feeds, 75% of grower feeds and 50% of finisher feeds incorporating antibiotics (Cromwell, 2002). The most frequently used antimicrobials in the swine industry include: tetracyclines, tylosin, and sulfamethazine or other sulfonamides (McEwen and Fedorka-Cray, 2002).…”

Influence of environmental stress on immunity of swine

“…Analizując mechanizmy stymulacji wzrostu poprzez stosowanie antybiotykowych stymulatorów wzrostu w paszy okazało się, że promocja wzrostu, powodowana przez stosowanie niższych niż terapeutyczne dawek antybiotyków, jest wyższa u świń znajdujących się w pomieszczeniach "brudnych" i wcale lub źle dezynfekowanych niż w kojcach o wysokim standardzie sanitarnym (3).…”