Part 2 of a two-part series on diseases that impact egg production and egg safety.
FIGURE 1. IBV ELISA SEROLOGY TWO WEEKS AFTER INJECTION WITH KILLED ND-IB-MG VACCINE.
By Kalen Cookson, DVM, MAM, ACPV
Fort Dodge Animal Health
The first half of this two-part series focused on the importance
of protecting the immune system
This part reviews
vaccination can help
prevent losses from
infectious bronchitis, mycoplasmosis
and E. coli, the three
Kalen Cookson diseases impacting egg-producing
flocks in the United States.
Inadequate administration of vaccine can influence serology.
Immunizing against three
Infectious bronchitis (IB)
The Disease—IBV replicates in and
damages the respiratory and reproductive tracts and, with some strains, the
The organ system which is compromised is determined by a number of
factors including age and immune status of the hen as well as the tissue tropism (preference) of the IBV strain.
Respiratory disease can exhibit as
any combination of signs including
conjunctivitis, swollen heads, rales
(snicking) and terminating in airsaccu-litis. Kidney damage can result in severe flushing, pasty vents and elevated
mortality. Infection of the oviduct before two weeks of age can result in a
significant prevalence of “silent or internal layers.”
Hens infected as chicks become
sexually mature but the oviduct is deformed resulting in either non-produc-tion or deposition of yolks in the body
cavity. Infection of the oviduct during
lay can result in dips in egg production
as well as poor interior (albumen) and
exterior (shell) egg quality.
Vaccination—Pullets should receive
three doses of a live attenuated vaccine when using an “all-live” program.
The first vaccination should be at two
to three weeks of age with subsequent
vaccinations usually spaced about four
to six weeks apart.
It is not uncommon for large in-line
layer complexes to be infected with
persistent variant IB strains.
Accordingly most operations benefit
from the addition of an Arkansas serotype in the pullet program.
Adding Arkansas to Massachusetts
and Connecticut strains for the first
two vaccinations produces the broad-est spectrum of immunity.
Mid-passaged Holland vaccine is
an effective booster for the last application. Programs using only live vaccines during rearing require boosting
of flocks every eight to 10 weeks during production to maintain local tissue immunity. Most IBV vaccines are
invariably given in combination with
Newcastle disease vaccines—either
the B1(early priming) or LaSota (later
Killed (inactivated) vaccines are often administered in place of the last
live vaccination. Because they stimulate much higher circulating antibodies, they provide maximum protection
of the oviduct and kidney when layers