In broilers, IB often leads to increased use of
medication in the field and higher condemnations
due to airsacculitis and colibacillosis, the veterinarian
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.
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.