WASHINGTON – A series of studies conducted by US Department of Agriculture scientists and their collaborators explore non-antibiotic methods to reduce foodborne pathogens that are found in the gut of food animals.

Team members include Agricultural Research Service microbiologist Todd Callaway, with the agency's Food and Feed Safety Research Unit in College Station, Texas; ARS animal scientist and project leader Jeffery Carroll with the agency's Livestock Issues Research Unit in Lubbock, Texas; and John Arthington at the Univ. of Florida in Ona, according to ARS’ Rosalie Marion Bliss.

According to early studies, citrus products provide cows with good roughage and vitamins, and the essential oils in such products provide a natural antibiotic effect. Callaway's early data highlighted the feasibility of using orange pulp as a feed source to provide anti-pathogenic activity in cattle. Consumption of citrus byproducts (orange peel and pulp) by cattle is compatible with current production practices, and the byproducts are palatable to the animals, the research also indicated.

He next shed light on how to exploit the essential oils inside the peel and pulp that are natural antimicrobials. Collaborations with researchers Steven Ricke and Philip Crandall at the Univ. of Arkansas in Fayetteville also have identified specific essential oils that kill the pathogenic bacteria.

Callaway recognized that citrus peel can be heavy and expensive to ship long distances from the time he began studying citrus as an animal gut cleanser, so his latest studies have investigated the use of processed orange peel pellets.

Dried orange peel pellets were fed to sheep by the team in one study as a model for cows for eight days. As a result, they found a tenfold reduction in Salmonella populations in the animals' intestinal contents.

A grant was awarded to Callaway from the National Cattleman's Beef Association (Beef Checkoff funds) to help fund the study. Results from the 2011 study were published in Foodborne Pathogens and Disease.