Iowa State University researchers Isabel Harris and Matthew Erdmann have found that hogs on small farms already have little or no Salmonella.

“These farms have very low levels of Salmonella,” explained D.L. Harris, an ISU Food Safety Consortium researcher and animal science professor. “They’re traditional farms that don’t use antibiotics.”

Harris’ research group surveyed 50 traditional family farms in the Midwest ranging in size from 20 to 150 sows. The pigs there are raised on open lots using management procedures with varying risks of contributing to Salmonella on the premises.

The researchers found that practices such as maintaining small herd sizes, limiting the use of vaccines and refraining from using growth-promoting antibiotics did not translate into high prevalence of Salmonella. But those practices apparently don’t have as much impact on keeping Salmonella levels low as do other practices such as the use of meal feed and straw bedding, low stocking densities or rodent control. The lesson here, Harris noted, is that avoidance of antibiotics by itself isn’t enough to keep Salmonella out. The other factors play more important roles.