Watch out, foodborne illness. You have a new enemy you probably never saw coming: orange peels. A new study from the USDA’s Agricultural Research Service (ARS) suggests that feeding the citrus skins to cattle can drastically reduce the prevalence of pathogenic bacteria (such as E. coli and salmonella) in cows’ gastro-intestinal tracts. Ultimately, cutting down on internal bacteria in living cows could translate into lower rates of dangerous pathogens in meat — and also help reduce the livestock industry’s dependence on potentially dangerous antibiotics.
The ARS study, lead by microbiologist Ted Callaway, brings together two long-running strains of research. The older one, stretching back as far as 1924, has demonstrated the anti-microbial properties of citrus oils time and time again.
The younger and smaller one has tried to find ways to use citrus wastes as animal feed. The Florida orange industry alone produces five million tons of orange peels and pulp, from products like orange juice and canned oranges, so the demand for a use for waste — other than the garbage dump — is high. Studies have shown that citrus peels contain a chemical, d-limonene, that is toxic to pigs and poultry. But cows, with their four stomachs, can digest orange peels without a hitch.
The ARS study demonstrated the potential antimicrobial efficacy of orange peels in cattle feed by feeding pelletized orange peel to sheep, which are ruminants like cows. (Pellets are considered more viable than raw skins because the latter are hard to ship.) The researchers then tested the digestive tract of the sheep for the presence of pathogens. They found that the orange peel pellets led to a “10-fold reduction in Salmonella and E. coli O157:H7 in the animals’ intestinal contents,” according to Food Safety News.
Callaway has said that his team’s next move will involve field-testing the new feed in cattle around the country.