Ithaca, New York
From: "The Stockman Grassfarmer"
According to a recent study, not only can conjugated linoleic acid (CLA) reduce
the incidence of heart disease, diabetes, and certain types of cancer, but it
can also prevent outbreaks of E. coli food poisoning. The best source of CLA is
from grazing ruminants and simply feeding cattle a hay diet for a few days
before slaughter could prevent E. coli food poisoning, researchers said.
Tests showed the grain diet now fed to most cattle created just the right conditions to allow bacteria such as E. coli to become dangerous. But some say the problem is easily solved by just cleaning out the guts of the cattle with a little bit of hay.
James Russel, a USDA microbiologist, and a team at Cornell University tested a herd of cattle and found that grain feeding created acid conditions in the digestive tracts of cattle.
"Most bacteria are killed by the acid of stomach juice, but E. coli from grain fed cattle are resistant to strong acids," Russel said. He also said that now that they know where the acid resistant E. coli is coming from, they could control them with a relatively inexpensive change in diet.
According to the team's report, their studies indicated that cattle could be given hay for a brief period immediately before slaughter to significantly reduce the risk of food-borne E. coli infection.
When E. coli is grown in a slightly acidic environment, it becomes acid-resistant. Then when people eat food or drink water infected with the bacteria, it can survive the acid in the stomach. It then makes it through to the intestines, causing diarrhea and other problems.
E. coli is one of the most common bacteria and lives in the intestines of many animals, including cattle and humans. In recent years a dangerous form, known as E. coli 0157, has emerged. This form infects about two percent of cattle and can be passed to humans through beef, or on fruits and vegetables that have been fertilized with manure. It does not hurt cattle but can give people diarrhea. Those with weak immune systems, such as children and the elderly, can die of kidney failure.
The problem stems from the fact that most cattle don't live in green fields, munching on grass. The cattle may start out that way, but in order to increase the growth rate, cattle are taken to large feedlots. At the feedlots they are fed diets that are rich in grain. Their guts are not designed for digesting starchy grain and much of it passes undigested into the colon, where it becomes the perfect breeding environment for acid-resistant bacteria.
Cattle in the study that were fed grass had non-acidic environments in their intestines, while those that got corn had acid gut contents. The E. coli from the cattle with acid guts survived the equivalent of human stomach acid, while the E. coli from the less-acid cow guts was killed by stomach acid. When switched to a hay diet, the acid-resistant E. coli numbers plummeted. Russell said the Cornell cattle did not produce the 0157 strain of E. coli, but he believed all strains of the bacteria would respond favorably to the hay diet.
This E. coli problem is becoming more and more common. In 1996, dozens of people became ill and one child died after drinking apple juice contaminated with E. coli bacteria. Last July, a two-year-old Georgia girl was exposed to E. coli 0157 in a public pool and died. And last year, an outbreak of E. coli prompted the USDA to close the Hudson Foods Inc. beef plant in Columbus, Nebraska, and recall 25 million pounds of the plant's ground beef.