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Philadelphia Area
DELAWARE
VALLEY BOBCAT
215-828-2800
Honev Grove. PA
NORMAN 0. CLARK
& SON INC.
717-734-3682
West Lawn. PA
CLARKLIFT
SERVICES
215-670-2950
Bethlehem. PA
215-868-1481
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Nationally, the economic
, impact of Mycoplasma gallisepti
, cum (Mg) on the table egg industry
'has been estimated at between
I $llB million and SISO million
annually.
Commercial egg producers in
southern California alone lost an
estimated $127 million in 1984
With more than 30 attachments available, you truly can do it all
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Write or call for free 32-page Buyer’s Guide.
Melroe Company
P 0 00x6019
Fargo, NO 58108-6019* (701) 241-8700
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Quarrwilla. PA
GRUMELLI’S
FARM SERV.
717-786-7318
EVERGREEN
TRACTOR CO.
717-272-4641
1-800-441-4450
Mill Hall. PA
DUNKLE & GRIEB
717-726-3115
MG INFECTIONS
Paul H. Patterson
Assistant Professor
Dept Of
Poultry Science
* V
1
Muncy. PA
BEST LINE
LEASING, INC.
717-546-8422
800-321-2378
MiHlinbum PA
BS & B REPAIR
717-966-3756
Honesdtla. PA
CHARLES H.
SIEPIELA, INC.
717-253-3334
because of Mg. Losses from this
outbreak, in production and costs
for Mg control programs,
amounted to more than $6.5
million.
Chronic respiratory infections
associated with Mg become more
severe and adversely affect pro
ducer profit if the disease is com
plicated with E. coli, Newcastle
disease, or infectious bronchitis
exposure.
infection can spread from the
hen’s respiratory tract to oviduct,
causing reduced egg production
and poor egg quality. Egg produc
ers experience lost revenues from
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Tgmintffc PA
S.P.E. INC.
717-265-4440
CLUGSTON
AG & TURF, INC.
717-263-4103
Hanovif. PA
FINCH SERVICES
717-632-2345
N-dmow. P*
CLUGSTON
FARM EQUIPMENT
717-573-2250
poor feed conversion, increased
medication costs, higher air sac,
and sep-tox condemnations in
addition to drops in egg production
and poor egg quality.
The preferred method to control
Mg in poultry flocks is to maintain
flocks free of infection and use
good management and sanitation
practices to prevent introduction
from outside sources. Unfortu
nately, in Pennsylvania and many
other states, Mg is already estab
lished on many multi-age farms,
and transmission from mature hens
to replacement pullets ensures its
existence. In situations where
eradication appears out of reach or
unobtainable, controlling the pro
duction losses appears to be the
only viable alternative.
There are several ways to counter the losses
associated- with Mg infections. One is the
therapeutic and prophylactic feeding of anti
biotics to reduce the clinical symptoms and
stress associated with Mg. However, the costs
of adding antibiotics to the feed and the
increased incidence of Mg-resistant organ
isms has made their use less desirable.
Vaccination of the pullets before they are
exposed to field strains of Mg on the laying
farm holds the most promise, according to
some researchers. Numerous studies have
demonstrated that vaccination against Mg can
cut egg production losses in half when com
pared to non-vaccinated birds exposed to the
disease.
Killed oil emulsion Mg-bacterins, live F
strain Mg, and the new Mycovac-L from
Intervet Inc. are the current vaccine alterna
tives. Shortcomings with the bacterins ate the
labor costs associated with injecting individu
al birds, concern for worker safety, and bird
lesions from the injection.
The use of the F-strain has been denied by
some state veterinarians because turkeys in
close proximity are susceptible to the live F
strain Mg. Early communications from the
field suggest that flocks vaccinated with
Mycovac-L are performing well. Unfortu
nately, actual hen performance and cost
analysis compared with non-vaccinated hens
have never been determined under Pennsyl
vania’s conditions.
Some suggest that comprehensive field
evaluations are the best way to evaluate vac
cine efficacy against drops in egg production
after field exposure to Mg. With this premise,
we conducted the following study to evaluate
the potential of Mycovac-L for Single Comb
White Leghorn hens in Pennsylvania. Our
objective was to compare the flock perfor
mance records for pullets immunized with
Mycovac-L with similar flocks given F
strain. Comparisons would include hen body
weight, feed consumption, feed conversion,
mortality, egg production, eggs per hen
housed, and case weights.
To carry out this study, we first identified
Mg-vaccinated flocks from the license appli
cations at the Pennsylvania Department of
Agriculture. Flock owners were contacted for
confidential use of their flock records and any
comments they had regarding bird perfor
mance or egg quality. Production records
from eight flocks immunized with F-strain
and 14 flocks immunized with Mycovac-L
were summarized. The records were pooled
into 10-week periods from 20-29 weeks,
30-39 weeks, 40-49 weeks, and 50-59 weeks
of production, and average values were com
pared statistically between the two
treatments.
The results are as follows. Mortality was
approximately the same between the two
treatments, only in the 40-49 week period was
it statistically higher for F-strain (.46 percent)
vs. Mycovac-L (. 13 percent) vaccinated hens.
Body weight was consistently reduced by F
strain vaccination in every 10-week period
comparison (averaged .16 pound lighter). No
statistical difference in eggs per hen housed
was detected; however, birds given the
Mycovac-L averaged one mote egg during
the periods we considered.
Statistically higher hen day production was
recorded for Mycovac-L treated birds at
30-39 weeks (89.4 vs. 88.3 percent) and at
40-49 weeks (BS.I vs. 83.7 percent) compared
with F-strain. No difference was observed in
feed per dozen eggs or feed consumption per