|
 In Oklahoma, farm workers are mixing manure from swine sick with
the disease, known as Porcine Epidemic Diarrhea virus (PEDv), into
the food of healthy animals to build their immunity.
In Kansas, farmers are spraying a mixture of hog manure containing
the virus and water on the noses of pigs to create a "natural
vaccine."
Across the Farm Belt, U.S. pork producers are doing whatever they
can to shore up their herds' defenses against the virus that killed
up to 8 million pigs, a tenth of the nation's herd, two years ago,
and that farmers fear could return this winter.
The virus, which causes severe diarrhea that kills baby pigs,
thrives in cold weather, and declining immunity in the U.S. herd has
raised the risk of another outbreak to the highest level since 2013,
when pork prices soared to record highs, veterinarians said. A
resurgence could drive up prices again and hurt profits for
processors including Tyson Foods and JBS USA [JBS.UL], which have
benefited from low hog prices.
Farmers are better prepared to fight the disease than they were two
years ago after implementing procedures to prevent the spread of the
virus via farm vehicles, workers' shoes and animal feed.
Veterinarians said that attempts to deliberately expose hogs to the
virus also help reduce the risk of an outbreak as big as the one
that began in 2013, although it is not clear how many farmers are
taking such precautions.
Michael Blackwell, chief veterinarian officer for the Humane Society
of the United States, said feeding baby pigs to other hogs "seems to
be pretty barbaric," but that he understands why farmers are doing
it. "It is not as inhumane as having millions of piglets killed in
an outbreak," he said.
VACCINES AND "FEEDBACK"
Veterinarians said commercial vaccines available from Zoetis Inc and
Merck & Co-owned Harrisvaccines offer limited help preventing
outbreaks. They do not specifically target the gut and are mainly
effective on hogs that have already been exposed to the virus.
Harrisvaccines said that vaccines are not a "silver bullet," and
Zoetis said there was not enough data that prove that vaccines
effectively protect herds that have not previously been infected.
Such limitations, along with concerns that immunity levels have
waned, make farmers turn to methods such as "feedback," where
intestines of piglets killed by the virus are fed to female pigs
used for breeding. Immunity has declined because a growing number of
hogs have never been infected, meaning they lack natural immunity
they could pass on to their babies, veterinarians say. Also,
immunity wears off over time in hogs that were previously infected.
Feedback allows female hogs to become infected and pass on immunity
to piglets, which are more likely to die from the disease than older
hogs. Those fed infected food or otherwise exposed to the virus
usually become sick for a few days, but then get well again.
[to top of second column] |
Purposefully exposing hogs to the virus is "really important because
that's one way we can have local establishment and local building of
immunity," said Lisa Becton, director of swine health information
and research for the National Pork Board, an industry group.
Matt Ackerman, a prominent hog veterinarian based in Indiana,
estimates that more than a million pigs could die between June 1,
2015 and May 31, 2016, from a return of the virus, far below the
2013 levels. Such losses would occur if 10 percent of sow farms
become infected, which Ackerman said was a "very real expectation"
that would be devastating to producers.
From July 1 to Dec. 4, 2 percent of herds cumulatively reported new
infections, according to an analysis from Bob Morrison, a professor
at the University of Minnesota. That is down from 56 percent between
July 2013 and June 2014 and 9 percent a year later.
For farmers seeking to deliberately expose their herds to the virus,
one step is to identify infected hogs, so they can serve as
"vaccine" donors. At Prestage Farms in Oklahoma, which sells hogs to
Seaboard Corp, workers place pieces of rope into pig pens for hogs
to bite. The rope is then tested for the virus, says Ron Prestage,
who runs a division of the family-owned company.
If the disease is detected, workers scoop up manure from the pens to
mix with feed for female breeding hogs, so they can pass on
antibodies to piglets through their milk, said Prestage, who is also
president of the National Pork Producers Council.
"They get a little bit of a belly ache and have diarrhea and then
get over it," he said.
(Reporting by Danny Na and Tom Polansek in Chicago; Editing by
Tomasz Janowski)
[© 2015 Thomson Reuters. All rights
reserved.]
Copyright 2015 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed. |
