14 September 1998
‘Feed cattle on hay to avoid E coli 0157

SCIENTISTS at Cornell University have shown that grain-based diets promote the growth of the food poisoning bacterium E coli 0157. This is the variety which caused a fatal outbreak in Scotland in 1996.

Cattle that are fed on hay do not show the same effect, the scientists report.

The research finds that cattle do not have enough of an enzyme which digests starch to process the grain-based diet fully. It means the starch gets through the digestive system to the colon, where it ferments.

This acidifies the colon. When bacteria grows under these acidic conditions, it develops the extreme acid resistance necessary to survive the stomach acids in humans, which are supposed to protect against food-borne pathogens.

The researchers found that switching cows to a hay-based diet before they are slaughtered means that the incidence of acid-resistant bacteria is reduced.