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Animal feed: render unto salmonella.

We're careful about the animal foods we eat. But what about the foods that are eaten by the animals we eat? One of those foods may be responsible for thousands of case of salmonella food poisoning every year. What is it? Animals.

The rendering industry has any number of polite terms for the 36 billion pounds of slaughterhouse waste it recycles every year: animal byproducts, viscera, offal (maybe tha should be "awful").

Just about anything left over after livestock is turned into Sunday dinner is ground up, boiled down, and sent back to the farm as animal feed. Ears and intestines. Tails and toes. Chicken heads and feet. Even poultry feathers are collected and transformed into a barnyard treat called hydrolyzed feather meal.

Fecal matter still inside animals that were fed too soon before being sent to slaughter?

Whoops. There's that, too. Some rendering plants even take roadkill and dogs and cats left in city pounds.

"From an aethetic point of view, it's a highly repulsive image," says George Mitchell, director of the Office of Surveillance and Compliance at the FDA's Center for Veterinary Medicine (CVM). "But from a biochemistry standpoint, it's perfectly acceptable. The rendering process sterilizes and kills everything that came from those old carcasses."

Rendering may sterilize the animal byproducts that end up in animal feed, but even after sterilization, they're a paradise for new bacteria.

"These are protein-based products that are full of amino acids and nutrients," says the CVM's Mitchell. "When salmonella get into them, they will survice for a long period of time. And given a little bit of extra water, the salmonella will reproduce in large numbers."

How do the salmonella contaminate the rendered byproducts? Through cracked pipes that transport the muck around the plant; wet or poorly cleaned work or storage areas; visitors tracking it into the plant on shoes and clothing; sloppy handling; contaminated trucks; even flies, birds, and rodents.

Once in the feed, salmonella can work their way into the eggs, chickens, and other meat that we eat. The results range from unpleasant--bouts of diarrhea, nausea, and sometimes fever and abdominal cramps--to fatal.

"About 40,000 cases of salmonellosis get reported to us annuall...[although] we think there are actually one to two million cases of salmonella infection each year," says Morris Potter, assistant director for foodborne diseases at the Centers for Disease Control (CDC).

The CDC estimates that about 2,000 deaths a year are caused by salmonella in chicken.

The FDA's Center for Veterinary Medicine is working with the U.S. Animal Health Association--a group of government, industry, and university scientists--to develop voluntary quality assurance programs for feed production and handling. Their stated goal: to reduce salmonella contamination in feed to zero.


Not surprisingly, the feed industry says that zero contamination is impossible. But, says CVM microbiologist Daniel McChesney, to aim for anything less would be pointless.

"Salmonella isn't like a pesticide or a drug. It grows. If you measure for it and find two, in two days it could be two billion. So there's no point in having anything besides zero."

How contaminated is our animal-feed supply? No one really knows. Though the FDA has jurisdiction over feed production, it doesn't routinely test rendering plants and feed mills for salmonella. It only tests when there is a contamination problem that has been traced back to a particular plant or batch of feed.


Feed isn't the only source of salmonella contamination. Birds and rodents carry it, farm environments teem with it, and livestock can pick it up en route to and from, or at, the processing plant.

"Even if we had sterile feed going into the mouth of every chicken, we would not solve all the problems as far as the dinner table is concerned," acknowledges the CVM's George Mitchell.

True. But "if you're going to start with the most contaiminated point in the production process," says North Carolina State University poultry scientist Frank Jones, "it would certainly be feed."

Former Assistant Secretary of Agriculture Carol Tucker Foreman agrees. "Getting salmonella out of feed won't get rid of the salmonella problem. But it's hard to fix the salmonella problem without fixing salmonella in feed."


There are more than 2,000 different species of salmonella, and only a few of the ones that have been found in feed have been linked to cases of salmonellosis in humans--a fact the feed industry never tires of pointing out.

"If you ask the FDA, they'll admit that they don't have a link establishing salmonella in feed as a cuasative agent of salmonella in carcasses," says Richard Sellers, director of feed control and nutrition for the American Feed Industry Association.

And he's right, at least about Salmonella enteritidis, the strain responsible for the recent outbreaks caused by contaminated eggs. But there's no doubt that salmonella can work its way from feed to dinner plate. It's just difficult to trace.

In 1972, though, a rare strain that entered this country in batch of Peruvian fishmeal was found to be the cause of a subsequent outbreak of salmonellosis in Arkansas. And the FDA is in no mood to quibble about which strains are a potential threat to public health.

"It's nonsense to say there's no 'smoking gun,' because all salmonella are pathogenic," says CVM Director Gerald Guest. "Some cause greater disease problems than others, but they're all pathogens."

Another common refrain of feed producers is echoed by the Feed Industry Association's Richard Sellers. "We wouldn't have problems if we could just get people to handle and cook meat properly."

That's good advice, but it's a bad excuse. It unfairly places all the burden on the consumer, and it diverts attention from an industry that refuses to clean up its act.


So how do we clean up feed? One way--the route chosen by the CVM--is to leave it up to the feed producers.

The American Protein Producers Industry (APPI), a renderers association, says that it has a program aimed at tightening contamination controls. The APPI claims to have test results showing that contamination levels have dropped by almost 50 percent at some rendering plants, but it refused to show us any data.

Robert Brown, president of Food-Animal Concerns Trust, a poultry operation with egg farms in Pennsylvania and Maine, says that attention to detail at the feed mills can make a big difference.

"We only buy feed that tests zero for all salmonella, and we don't have any problem getting it," he says. "It's a matter of good housekeeping, not a trip to the moon." It helps that he orders feed with roasted whole soybeans instead of meat and bone meal, which are the primary carriers of salmonella.

"We can't guarantee that our eggs are completely salmonella-free," he says. "But we've greatly reduced the chances of them having Salmonella enteritidis. And if tiny us can do it, why can't the big guys?"

They can't because they won't...not unless the FDA forces them to.
COPYRIGHT 1992 Center for Science in the Public Interest
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:includes related article on bovine spongiform
Author:Kuznik, Frank
Publication:Nutrition Action Healthletter
Date:Apr 1, 1992
Previous Article:Food irradiation: zapping our troubles away?
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