Raising pigs on pasture reduces the risk of fostering antibiotic-resistant bacteria

A herd of pigs that had not been exposed to antibiotics for 126 months was divided into two groups and either housed on pasture or in standard indoor units. Over a 20-month period, fecal coliforms from both groups of pigs were tested for resistance to standard antibiotics. Samples taken from the pastured pigs were far less likely to be antibiotic resistant. "The data from this study suggest that exposure to antibiotics is not the only factor that influences the prevalence of bacteria that are resistant to single and multiple antibiotics in the feces of domestic animals and that considerable research is needed to define the factors influencing antibiotic resistance in fecal bacteria."

Langlois, B. E., K. A. Dawson, et al. (1988). "Effect of age and housing location on antibiotic resistance of fecal coliforms from pigs in a non-antibiotic-exposed herd." Appl Environ Microbiol 54(6): 1341-4.