Wisconsin's Mad Deer Epidemic-
The Feed Connection


CWD: Report from Ground Zero

Did the push for a bigger. better buck create the conditions for a tragic

By Mike Irwin
Special to The Capital Times (Madison, Wisconsin)
July 20, 2002

TOWN OF VERMONT - One chilly evening in the winter of 1990 a
group of local deer hunters - farmers, neighbors and kin - gathered
for a chili supper at a farmhouse here to brainstorm about how to build
a better buck.

Out of the conversation came a pact. They agreed to a long-term plan to
refine the white-tailed herd in their area, including 12 square miles in the
northwestern part of the town of Vermont, in western Dane County.

Beginning that year, they would shoot many does but spare young bucks.
They would give the males three to five years to develop the big bodies and
splendid antlers that could qualify them as trophy candidates for the Pope
and Young and Boone and Crockett record books.

So Part 1 of the pact was selection. Part 2 was nutrition.

"We'd come from dairy farming families, so we took our cues for improving
the herd from that background," recalled a woman who took notes after the
chili supper.

"We asked: 'What do the animals need that they might not be getting from the
environment?' " Their ground was flinty, she noted, and forest soils were
not high in calcium or phosphorus, the stuff that nursing does and
fast-growing bucks "in velvet" need.

Deer were ruminants, like sheep or cattle, they reasoned. Why not supplement
their diets, as farmers did for livestock, with pasture lots and licks?
"Couldn't hurt, might help," one farmer said at the meeting.

So the group agreed to start - or, since some had already started, continue
- a long-term program of supplemental mineral feeding of wild deer aimed at
doe-fawn and buck health and the making of big antlers.

Within a few years, the results began to appear in the trophy books.

Of 152 Dane County bucks earning enough total points for registration
between 1980 and 2000 in the Pope and Young Club's "Bowhunting: Big Game
Records of North America," 136 were registered between 1990 and 2000.

Of the 136, 84 were killed between 1996 and 1999. Bucks with the highest
scores for antlers dominated the years 1996, 1997 and 1998.

Clearly, something was working. Then, this year, something horrible

Eleven cases of chronic wasting disease - a devastating brain disease not
before seen east of the Mississippi River - showed up in deer specimens
taken by the Wisconsin Department of Natural Resources from land, including
one DNR-owned parcel, in the 12 tightly clustered square-mile sections of
the town of Vermont. This was the area where the chili supper group was

DNR epidemiologist Julie Langenberg said in an interview that the cluster
"suggests original cause. We're gathering data and asking questions."

Do the questions include whether the innocently begun nutrition and
selection practices of local hunters may have created the conditions for the
introduction of the disease and given it the years it needs to develop?

The DNR did collect feed samples in the days immediately after the first
cases were reported. Thomas Solin, chief of special operations in the DNR
Bureau of Law Enforcement, said Thursday that wardens canvassed the area "to
get a snapshot" of conditions. Part of that involved collecting feed blocks
from farmers and hunters and also purchasing blocks from local suppliers.

"A lot of people there were actively feeding. Once we captured the
information we turned it over to the Department of Agriculture, because they
regulate the feed. If they want to test, we have samples available."

But Eric Nelson, feed program manager for the state Department of
Agriculture, Trade and Consumer Protection, says there are no procedures to
test feed products for the presence of CWD. "With feed microscopy you can
tell the difference between mammals and birds and that's about it," he said
in an interview Friday.

"We did inspect feed manufacturers and deer feeders and found all products
to be in compliance with the federal regulation banning rendered ruminant
materials. There were no prohibited materials in any materials we

The science

Thirty-five years of scientific study show that epidemics of the fatal brain
diseases of the class known as transmissible spongiform encephalopathies
(TSEs) have been largely bred by human behavior and spread by animal

Chronic wasting disease (CWD), like its cousins mad cow disease and sheep
wasting disease or scrapie, is caused by a protein fragment called a prion,
not a bacterium or a virus but a chain of amino acids that lives in the
brain and nervous tissue. As was found in England, it can be introduced from
dead animals to living ones through feed containing rendered meats and bones
of diseased animals.

To do its full damage to a living animal, it must have years to develop.
Studies report the incubation period between first contact and visible
symptoms in deer is between one and a half and five years.

As the disease develops, the animals may spread it through many kinds of
contact. It may go from deer to fawn. If wild herds are concentrated rather
than dispersed - in areas such as Mount Horeb, where urban development
narrows their range and feeding intensifies contact - it may be spread
through saliva on food blocks, and in areas where deer bed down and leave
their droppings. The prions can contaminate the soil where deer congregate.

One study in 1999 showed that feed itself can transmit the disease. In the
study, mule deer fawns were fed a preparation of brain tissue taken from a
mule deer with CWD. The protein marker, evidence of infection, was found in
the lymph tissue of the digestive tract after fawns were sacrificed. At 42
days the first fawn autopsied showed infection. All of the fawns showed
infection after 53 days.

Wisconsin's Eric Nelson scoffed at that study Friday. "They were using raw
brain material and it wasn't natural feeding," he said. "If it had been
rendered, the infectivity would have been greatly reduced."

He adds flatly: "There is no evidence to support the idea that CWD can be
spread by feeding."

Researchers have found TSE prions to be nearly indestructible. They can
remain viable on sterilized surgical tools. Clinical studies report that
heats of 680 degrees Fahrenheit are required to kill these agents.
Controlled studies have shown them to live in soils for seven or more years.

Richard Marsh, a renowned UW-Madison researcher, once warned a statewide
farming audience that Wisconsin was especially vulnerable to TSE outbreaks
because "we have so many animals here and so much rendering of them."

In 1982-83, Marsh asked Blair McMillan, a post-doctoral researcher and
Madison-based epidemic microbiologist, for some help. McMillan's mentor then
was UW epidemiologist Robert Paul Hanson. The three sought to understand
transmission of the TSEs, but also the makeup of their infectious agents.

"I looked at this tiny, tiny fragment of protein - nucleic acid, this prion
or virino, from a sheep scrapie-infected brain," McMillan said in an
interview. "What I learned above all was that it was so small you couldn't
kill it. It took intense heat. Even if you tried to irradiate it, you had to
find it first."

McMillan, now a senior microbiologist and epidemiology specialist teaching
at Madison Area Technical College, approaches the town of Vermont CWD
outbreak with the caution of a scientist.

"You've got a true disease cluster out there. You've got your index (the
first case) identified. Maybe the disease was there first, but now science
has seen it," he said. "The geographic boundaries and timeline of the
outbreak suggests a sole source of infection."

Still, to settle on a single cause for transmission makes McMillan very
uncomfortable. Was that source deer feed containing animal byproducts? Or
was it animal-to-animal contact? Or prions lurking in the soil at feeding
stations where animals also had contact?

"You have science showing soil contact is possible, science that doe and
fawn eye-to-mouth or afterbirth contact is possible. Moving across species
to a new form, sheep to deer or cattle to deer is possible, but less likely.
Next, you show me that deer are eating with infected deer, or eating
rendered, infected deer" - and you'll have it."

But until then? He shakes a handful of pepper grains into his palm and
tosses them toward the sidewalk just as a breeze comes up. "There are your
infectious prions. They're out there. Go find them," he says.

The feed barns

As early as 1991, the U.S. Department of Agriculture created a voluntary ban
on feeding rendered sheep byproducts to cattle.

On Aug. 4, 1997, in the wake of Britain's mad cow epidemic, the federal Food
and Drug Administration placed a more extensive ban on ruminant-to-ruminant
feeding. Ruminants included cattle, sheep, elk, buffalo, goats, antelope and
deer, according to the rule.

But between 1991 and 1997, before the ban and while the deer feeding program
was under way in the town of Vermont, Wisconsin deer carcasses and body
parts did go to rendering plants. There they were processed into meat meal
and bone meal and could legally be fed back to healthy deer.

In the 1994-95 fiscal year alone, just under 26,500 road-killed or seized
white-tailed deer were picked up statewide by contractors for disposal at
rendering facilities, according to 1995 DNR Bureau of Law Enforcement

A Wisconsin Meat Trades Association official, who asked not to be
identified, recalled that before 1991, all his slaughterhouse offal and body
parts went "down the road together" to rendering plants. After that, he
said, unused sheep parts were rejected. But until August 1997, deer, cattle
and other mammal body parts continued to be collected together for rendering
in the same containers, dumpsters and vats.

Processing and rendering industries' common practices help explain how the
CWD agent could have ultimately entered animal feeds and mineral

Larry Meicher, a hunter since 1976 who lives on the eastern side of the town
of Vermont, outside the cluster, remembers seeing "deer blocks with animal
products" ingredients on the label in 1995 at a suburban feed outlet west of
Madison. If deer were accidentally fed contaminated feeds or minerals
between, say, 1991 and 1997, the CWD disease symptoms clearly would be
showing up now.

Between the mid to late 1980s until Aug. 4, 1997, it was legal and everyday
practice in Wisconsin farm co-ops and private feed mills to blend ruminant
feeds to include dry, prepared, rendered animal products. These specifically
included meat meal, bone meal or both.

They used rendered materials because they were inexpensive compared, for
example, to soybean meal. The rendered meat meal contained an average of 50
percent protein. The rendered bone meal contained 8 percent to 12 percent
calcium and 4 percent to 6 percent phosphorus.

For deer muscle and antler growth, the bone meal seemed a good supplement.
One of the women in the town of Vermont quality-deer group happened to work
at a local co-op during the pre-ban years. "I was one of the promoters," she
said. "We recommended 4 percent bypass (rendered) protein. We'd put it in
dairy rations," she said, and recalled that pasture minerals had bone meal
in their recipes as well.

"But even before we came in 1987, they were feeding mineral supplement out
here," her husband said. "It's what farmers did. We all were doing it.
People out here were putting together their own formulas. The whole
community was doing it."

DNR investigates

In talking with local residents and hunters, this reporter collected three
firsthand, eyewitness "sick deer, skin-and-bones deer" stories going back
four to five years.

DNR wardens no doubt heard some of the same stories and acted on them. Well
before the 2001 hunting season, through deer brain sampling at the Mount
Horeb deer registration station, DNR specialists had formed a working
hypothesis that the disease was present -- at least in western Dane County.

Last year, they bore down on the Mount Horeb station. Of all deer brain
testing done statewide during last falls gun hunt across Wisconsin, fully a
quarter of all samples, 82 out of 345, were from the Mount Horeb station and
from Management Unit 70A. Three positives for CWD appeared. They came from
Sections 19 and 21 in the northwest part of the town of Vermont. The first
positive, what epidemiologists call "the index case," came from Section 21.

This information prompted the March-to-May shoot of this year that added 416
samples from other Dane and Iowa County towns abutting the town of Vermont.
It also eventually established a fully identifiable disease cluster, with 11
of 18 total cases, 63 percent, appearing in 12 abutting square-mile sections
of the town of Vermonts northwest corner.

With the cluster identified, what would the next logical step be? Harvard
University epidemiologist Melissa Perry suggested in an interview: "Your
state people might find the mineral feeding sites in the disease cluster and
try to correlate them with sites where they found deer testing positive" for
the disease.

The DNR did just that.

"I never had thought about feeding as a possible way to spread the disease
until a warden came over this spring and asked, Whats in your mineral
supplement? " one landowner said in an interview. "I never thought about
animal byproducts being in our mineral supplements before 97. Maybe mineral
feeding was a link."

The DNR responded to what it found with a proposal to ban baiting and
feeding in the CWD outbreak study area. On June 25, the Wisconsin Natural
Resources Board, despite intense opposition, imposed a statewide ban on deer
feeding as part of its emergency policy to halt the epidemic.

DNRS Solin said Thursday: "We do know that feed concentrates the herd, and
thats why the ban was put in place. Feed concentrates animals, and if a
lateral transmission occurs through saliva, stopping feeding reduces the
chance of spreading it. Its going to take research and time to figure out
what happened."

Scorched earth

Today, the group that met a dozen years ago with dreams of cultivating
awesome trophy bucks feels devastated, as the order has gone out to kill the
entire wild herd in their area and in an expanded area around them, an
estimated 25,000 deer.

"Out here, we are a community that is grieving. We know our lives will never
be the same again," one of the hunters said in a phone conversation late in
May. "We've loved and respected the deer so much."

But the man, whose wife described him as the kind of sportsman who is
"awestruck over the greatest buck or the tiniest fawn," is doing his part to
stop the spread of CWD. With his DNR-issued special landowner permit, he has
taken up his rifle.

"I shot eight deer for the DNR this past month, and by the eighth I was
numb," he said. "I had no feeling at all."

Published: 6:58 AM 7/20/02

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