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Reducing
the presence of E. coli may come down to the producer
level |
Excerpts
taken from: Beef Today 12/15/02, by Holly Foster
& Steve Cornett
Recent news of contaminated beef
being recalled has raised concern about the levels of E.
coli in our country’s beef supply.
Packers and processors have been taking measures on
their part to reduce contamination, but the next step may be
for producers to reduce the levels of E. coli in the cattle
before they reach the processor.
“We’ve already reached our limit at the
processing level, and preharvest measures will make the most
difference in the future,” says Mindy Brashears, a food
safety researcher at Texas Tech University.
That’s
the thought behind a raft of research aimed at helping
producers find ways to provide packing plants with cleaner
animals. If E. coli shedding rates on live animals are
reduced even 50%, then postharvest intervention methods will
be that much more effective, according to Rob Elder, a
USDA– Agricultural Research Service scientist. For years,
most producers have stuck to the position that bacterial
contamination is a packer problem. But in a paper
co-authored by Elder in the 2000 Proceedings of the National
Academy of Sciences, what were previously thought to be low
rates of E. coli on animals entering packing plants
(approximately 1%) were actually hovering closer to 60%.
“Dealing
with E. coli O157:H7 on farms and feedlots is really the
next step to make a large impact,” says Elder. “Even a
50% to 75% reduction of E. coli levels in cattle before they
get to the plant will vastly increase the effectiveness of
postslaughter intervention methods.”
Whether
it is a question of liability or a lack of understanding,
producers have been reluctant to join the fight against E.
coli, but the issue may soon be forced upon them. Kansas
State University just received a grant from USDA Cooperative
State Research, Education and Extension Service for $534,153
to develop and implement a voluntary HACCP program for the
commercial feed industry. There are several intervention
methods that hold a lot of promise.
A draft document from the American Meat Institute Foundation
lists several that are currently being researched:
Feed additives
•Probiotics (Lactobacillus strain and certain E. coli
strains)
•Chlorates
•Colicins
•Tasco-14 better known as brown seaweed from Nova Scotia
•Water treatments
•Chlorine
•Chlorates
•Several other chemicals are being looked at, but the
highly variable rates of contamination in water troughs may
be a limiting factor
•Vaccines
•Several research institutions are investigating vaccine
protocols. The seasonality of O157:H7 shedding—which peaks
in September—makes it time consuming to validate the
effectiveness of a vaccine. It will likely be some time
before a vaccine is commercially available.
•Cattle washing and dehairing
•Some chemical washes for live cattle show promise, but
none is currently approved. Postmortem, chemical dehairing
has already been applied commercially, but waste disposal is
a challenge.
Brashears has spent the last five years looking at
direct-fed microbials or probiotics that have reduced
O157:H7 on hides by 80%. The
University of Nebraska and researchers in Canada have been
able to show similar results and have high hopes for this
product, which is already approved for use in the industry
to improve feed efficiency. However,
probiotics and several other methods under study will
require more validation as safety intervention methods
before they can be cleared for use.
Elder has been investigating the prudent feeding of neomycin
sulfate as another method of decreasing pathogen loads on
live cattle. “We can use this antimicrobial to treat
end-stage cattle, and neomycin has also been shown to
eliminate O157:H7 from fecal material,” he says. The
antibiotic is already approved for use in beef cattle.
While there is no
requirement or limit for the amount of E. coli contamination
for live cattle coming into plants, it is a problem that
beef producers may soon have to face as they consider
marketing their animals.
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