ASO-Lancfciter Farming, Saturday, November 18, 1995
Immune Breeder Flocks Key To Controlling CAV
ANDY ANDREWS
Lancaster Farming Staff
MANHEIM (Lancaster Co.)
It’s been said the best way to fight
disease is to prevent it That may
be the only way to stem the devas
tating'effects of a combination of
diseases that could destroy a flock
once chicken anemia virus (CAV)
takes hold.
Dr. Bob Owen, Hubbard Farms.
Inc., in Walpole, N.H., told neatly
30 poultry producers and agri
industry representatives that the
key to fighdng CAV is to use
immune breeder flocks that have
already been exposed to the virus
and can pass CAV-flghting antibo
dies to the chicks.
Owen spoke Monday afternoon
during the Penn-State sponsored
Poultry Management and Health
Seminar at Kreider’s Restaurant in
Manheim.
Owen admitted how difficult it
is to diagnose the disease. The dis
ease is not new, however. It was
first recorded in Japan in
1978-1979. And (here’s “serolog
ical evidence for this virus several
decades before 1978,” said Owen.
“It appears to be a new disease
to us because we Finally have been
able to diagnose it It’s probably
been around for years and yean
and yean."
The widespread virus is known
by other names, including chicken
anemia agent (CAA), blue wing
disease (seen as gangrenous der
matitis in broilers), as well as
infectious anemia. It affects broil
ers and layers. The disease is
caused by a virus and only recently
has been classified as a member of
the circoviridae family.
Owen said the virus is "the
smallest vims that we know of in
veterinary medicine," part of a
family of viruses that can affect
pigs and birds. The virus is small,
measuring only IS nanometers in
diameter with less than 1,760 base
pairs.
(As a point of measurement,
according to Owen, CAV is 10
times smaller in diameter than the
coronavirus that causes infectious
bronchitis in chickens. The coro
navirus measures 100-120
nanometers in diameter.)
There is only one serotype of
CAV.
In the clinical form, CAV shows
up in the birds at about two weeks
of age as anorexia (the birds don’t
want to eat) and they look pale.
They sit around like any chicken
does when sick, with ruffled feath
ers, according to Owen. Chickens
tend not to gain weight as rapidly
as their unaffected mates. Mortali
ty peaks 5-6 days after the first
sips and can affect from 10-60
percent of the flock.
In the subclinical form, the dis
ease can act in concert with some
of the immunosuppressive viruses
such as infectious bursal disease
virus (IBDV), Marek’s Disease
virus (MDV), and reovirus.
Owen said, “This virus, com
bined with those other viruses,
decreases the immunoresponsive
ness of the birds. Does this sound
like the same picture we used to ’
paint with IBD, that we still paint
with IBD?”
The problem is, CAV alone
doesn’t cause a great deal of dis
ease in the birds but acting
together with other agents, it can
be devastating to flocks.
When examining deceased
birds, veterinarians see gross
lesions. Owen spoke about a trip
made to South Africa to take a look
at 4-week-old bir<)s heavily
infected with CAV. "It’S really
very dramatic when you see it,” he
said. “There were chickens lying
everyplace. Every one of them that
we opened up had no thymus
(gland) at all and the skin was fall
ing off their wings because of
infection. It can be a devastating
infection when it gets into your
birds.”
The blood of clinically infected
birds is very thin and watery. The
bone marrow, rather than being a
healthy, vibrant red, is actually a
pale yellowish brown. There is
muscle hemorrhaging. And broil
ers, particularly, can have dermati
tis that is gangrenous the “wet
lesions” from which the term
“blue wing” originated.
It is difficult to determine if
birds have the ‘ ’subclinical form,’ ’
in which they don’t exhibit signs of
CAV infection but cab pass them
onto offspring. There is research
on coming up with an ELISA test
For Owen’s serology, he sends
samples from the flocks down to
the University of Arkansas where
they do a “virus neutralization”
(VN) test to check for the birds’
antibodies to the disease.
The VN test is inexpensive ($25
Berks Livestock Clubs Hold Banquet
KUTZTOWN (Berks Co.)
On Nov. 4 at the Kutztown
Grange Hall, the Bedes County
4-H Livestock Clubs held their
annual banquet. More than 250
4-H’ers, parents, supporters, and
friends attended the. banquet
4-H’crs were recognized for
their outstanding achievements in
different areas of the livestock
program. This year the 4-H’ers
were given a new challenge?£ach
4-H’er was given an activity book,
for the species they were carrying
as their project. These activity
books were very educational as far
as learning about their species and
also teaching some important life
skills.
Beef club awards are as
follows:
• Troy Gelsinger (most helpful
member, senior showman, senior
fitter, reserve champion steer,
champion heifer)
• Mark Manwillcr (intermediate
showman)
• Ben Weist (junior intermedi
ate showman, most weight gain
steer, junior activity book)
• Kristy Dietrich (junior
showman)
• Kelly'Dietrich (intermediate
fitter and intermediate record
book)
• L';e Gauker (junior intOT.edi
ate fittc;)
' Oath’
Sheep chib awards want to front row, Amanda Millar,
Cathy Lavan, Nicola Knapp, Katie Ramsay. Back row, Las
Gaukar, Justin Lavan.
per flock) and effective, according
to Owen.
Probably the only way to ensure
the clinical form of the disease
doesn’t show up in the flock is to
check to be sure “that we don’t
have any breeder flocks that fall
into this non-immune status,” said
Owen. “We can be assured that
the birds in this that are not going
to be challenged in the breeder
house are probably going to be
challenged in the brooder house.”
Producers should be sure to
have immune breeder flocks.
This is difficult to do with
hand-new houses that are in non
poultry areas of the country. Sev
eral are being constructed in Ten
nessee and managers should be
concerned about the evidence of
the virus.
Because the USDA still believes
theCAV is still an “exotic” virus,
according to Owen, there is no
vaccine available for it in the U.S.,
although researchers ate working
on developing one.
In the meantime, there are few
viable alternatives. One is to
“move” poultry litter from an
established house where the flock
• Melissa Leiby (senior record
book)
• Emilie Miller (junior record
book) .
• Christina Schoener (senior
activity book)
• Josh Krill (intermediate activ
ity book)
• David Newpher (champion
steer and reserve champion heifer)
Swine club awards:
• Jill Schick (senior showman,
senior fitter, reserve champion
carcass hog)
• Anita Manbeck (intermediate
showman)
• Brian Hartman (junior
showman)
• Steven Ynunker (intermediate
fitter)
• Lara Schick (junior fitter)
• Stephanie Manbeck (senior
activity book, senior record book,
reserve champion hog, champion
carcass hog)
• Justin Levan (intermediate
activity book)
• Matt Manbeck (junior activity
book)
• Katie Kochera (intermediate
record book)
• Ben Wcist (junior record
book)
• Troy Gelsinger (champion
hog)
Sheep club awards:
• Cathy Levan (junior shepherd,
- show*"' i)
Dr. Bob Owen, Hubbard Farms, Inc., In Walpola, N.H.,
right, told nearly 30 poultry producers and agri-industry
representatives that tha key to lighting CAV Is to have
Immune breeder (locks that have already been exposed to
the virus and can pass CAV-flghtlng antibodies to the
chicks. At left Is Dr. Bill Weaver, professor and head, Penn
State Department of Poultry Science.
tested positive for it to a new The key to control is prevention,
breeder flock, thus ensuring that and prevention is having positive
the chicks can obtain maternal breeder flocks. “I think every
antibodies to the disease and be breeder flock should be monitored
able to fight it naturally. But this at 8-10 weeks of age,” said Owen,
exposes other threats to the birds. As for CAV, “we need to be
such as Salmonella and other conscious ofand we need to recog
nize it when we see it,” he said.
• Kelly Glaser (senior shepherd,
intermediate showman, intermedi
ate fitter, intermediate record
book)
• Nicole Knepp (senior show
man, senior fitter, senior record
book)
• Amanda Miller (junior fitter,
junior activity book)
Beef club awards went to front row, Melissa Lelby, Troy
Gelslnger, Cathy Levan, Kristy Dietrich, Mark Manwlller.
Back row, David Newpher, Lee Gauker, Ben Welst, Kelly
, rroy. igi .Staphv
Back row, Lara Schick, Brian Hartman, Ban Walat, Stavan
Younkar, Anita Manback.
• Stephanie Bowman (senior
activity book)
■ Justin Levan (intermediate
activity book, reserve champion
lamb)
• Lee Gauker (junior record
book)
• Katie Ramsay (champion
lamb, champion pair of lambs)