In broilers, IB often leads to increased use of
medication in the field and higher condemnations
due to airsacculitis and colibacillosis, the veterinarian
reported.
In breeders, IB results in poor hatching, egg
production and mortality. An added complication
is frequent co-infection with avian metapneumovirus,
which requires its own vaccination,
he added.
In one field example cited by Assayag, broiler flocks
affected with IB had watery feces, extremely wet
litter and were depressed and rough-feathered;
they also were severely dehydrated, which was
indicated by dark muscles, and had kidney lesions,
mild airsacculitis and contact dermatitis. Mortality
was elevated by 3%.
A field case involving breeders was characterized
by watery feces, severe dehydration, kidney lesions,
airsacculitis, contact dermatitis and a 0.5% increase
in mortality, he said.
Economic Impact
The economic impact of IB has been significant:
Over US $3 million annually for broilers and nearly
US $4 million for breeders, Assayag continued.
The company, which has its own facilities where
IB viruses can be typed using polymerase chain
reaction (PCR) and genetic sequencing, also
conducts challenge trials in its lab as well as field
trials. It has found that 58% of IB viruses affecting
its flocks are of the Massachusetts serotype and
42% are IB variants, he said.
Brasil Foods uses testing results to adapt its vaccine
programs to the IB challenge as needed. In broilers,
it has administered IB H120 or Ma5, both of the
Massachusetts IB serotypes. “The protection with
an IB Ma5 vaccine is much higher, and it’s a better
vaccine to use because you don’t have to vaccinate
as many times,” Assayag said.
In breeders, the vaccination program used also
varies depending on the IB challenge and is tailored
to meet the needs of these longer-lived birds that
need protection longer than broilers. The company
may use a live IB Ma5, H120 or both vaccines to
start, followed by killed IB vaccines such as Mass
or the variant D274, and then revaccinates during
production with two killed vaccines.
“We use those two inactivated vaccines with good
results when there is a very high IB challenge,”
Assayag said.
The concept of Protectotype — using more than
one IB vaccine from serotypes that have crossprotective
ability — “is a very important way to
look at infectious bronchitis if we want results in
the field,” he said.
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