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Thurston County Extension

Food Safety: Food Borne Illness

Cows’ Diet Could Reduce E. Coli Risk

The Olympian, October 21, 1998

 Recently, Cornell University released the results of a exciting new study that may dramatically improve food safety in beef production. 

 Land Grant universities such as Cornell and Washington State University, often in association with the U.S. Department of Agriculture and Cooperative Extension, are frequently involved with research studies that directly impact the quality and safety of our food supply,  including research that could decrease the incidence of pathogenic or disease causing E. Coli in beef products. 

QUESTION:  Why is this research important to consumers?

 ANSWER:  The digestive tracts of cattle can promote the growth of pathogenic strains of E. Coli including E. Coli 0157:H7.  While most strains of E. Coli do not cause illness, the few that do can contaminate processed beef such as hamburger and infect manure that may find it’s way into our food chain. 

 The preliminary findings of this study indicate that changing the diet of the cattle from grain to hay for several days prior to slaughter could significantly reduce the risk of food-borne E. Coli infection. 

QUESTION:  Could you briefly explain the basics of the research project? 

ANSWER:  The Cornell scientists think that the E. Coli outbreaks may be due to diet changes in beef cattle in the last 20 years.  Basically the research team studied the gastrointestinal tracts of 61 cattle receiving three different kinds of diets for three or more weeks. 

 The diets consisted of hay or grass, 60 percent corn, and 80 percent corn.  After consuming the diets, the researchers studied amounts and types of E. Coli present in their intestinal tracts and feces.  It’s important to know that not all strains of E. Coli are pathogenic or disease causing. 

 They found dramatic differences in the number and acid resistance of E. Coli bacteria among the three groups of cattle.  The grain fed cattle had more than 6 million cells in every gram of feces, while the hay group showed 20,000 cells per gram.  They also found that the grain fed cattle had colon contents that were up to 100 times more acidic than those of hay fed cattle. 

The scientists think that the cattle have a more difficult time breaking down the starch found in the grain.  Therefore more grain passes into their intestines undigested and leads to a fermentation process that provides nutrients or food for bacteria like E. Coli to grow and multiply.  The fermentation process also produces acid, and the bacteria that survive become tolerant or resistant to it rather than be destroyed.  The head of the project at Cornell University, James Russell says that their research work showed that if you feed cattle hay for five days you can eliminate all acid-resistant E. Coli.

B.    Susie Craig

Area Faculty

WSU Cooperative Extension Thurston County

WSU Extension programs and employment are available to all without discrimination.  Evidence of noncompliance may be reported through your local Extension Office.   Cooperating agencies: Washington State University, U.S. Department of Agriculture, and the county of Thurston.

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