Avishield IBD Plus, Lyophilisate for Use in Drinking Water for Chickens

The optimal vaccination date is influenced by a number of factors, such as status of
maternally derived antibodies, type of bird, infection pressure, housing and
management conditions.
Maternally derived antibodies (MDA) can interfere with the immunity induced by live
IBD vaccines, so the optimum age for vaccination depends on both the level of
residual MDA against IBD in the flock and ability of the vaccine strain of avian IBD
virus to induce the required level of immunity in the presence of MDA. To predict the
age when the MDA titre has sufficiently decreased to allow effective vaccination
(break-through titre), testing of serum samples of at least 18 chicks by serology and
use of the Deventer Formula is advised. When high titres are expected, later
sampling (i.e. on day 7) will give a more reliable estimation of time of vaccination
than sampling on day 0. A break-through titre of 500 (IDEXX standard ELISA) should
be used. If other ELISA kits are used, obtained titre values need to be corrected to
correspond to IDEXX standard ELISA kit.
The Deventer formula is as follows:
Vaccination age = {(log2 titre bird% - log2 breakthrough) x t} + age at sampling +
correction 0-4
In which
Bird% = percentage of the flock that can be efficaciously vaccinated (having MDA
titres below break-through titre)
Log2 titre bird % = ELISA titre to be used is the highest ELISA titre in certain
percentage of all serums taken on sampling day, after their antibody titres are ranked
from the lowest to the highest. This percentage of samples corresponds to the
percentage of flock that can be efficaciously vaccinated (having MDA titres below
break-through titre)
breakthrough = breakthrough (ELISA) titre of the vaccine to be used
t _ = half-life time (ELISA) of the antibodies in the type of chickens being sampled
Age sampling = age of the birds at sampling
Correction 0-4 = extra days when the sampling was done at 0 to 4 days of age.
For examples and more information about the use of the Deventer Formula please
refer to
the Deventer formula, or contact the marketing authorisation holder.
In drinking water use
• Suspend the vaccine in a small amount of cool and clean water without traces
of chlorine, other disinfectants or impurities, in a number of doses
corresponding to the number of birds to be vaccinated. Where the number of
birds is between the standard dosages, the next higher dosage should be used.
• Vaccine should be suspended immediately before use.
• Measure the correct volume of water for the number of birds to be vaccinated.
The volume of water for dilution depends on the age of the birds, breed,
housing conditions and weather conditions.
• The resuspended vaccine should be diluted in the amount of water which will be
consumed within 1.5 to 2.0 hours (taking into account the different types of
drinking systems for poultry).
• In order to determine the quantity of water in which the vaccine will be diluted,
measure the volume of water consumed within a two hours period one day
before vaccination.
• As an orientation guide for younger chickens (until 3rd week of life), apply the
reconstituted vaccine to cold and fresh water at the rate of 1000 doses of
vaccine to 1 litre of water per day of age for 1000 chickens, e.g. 10 litres would
be needed for 1000, 10 days old chickens.
• In order to make the birds thirsty, withdraw the supply of drinking water up to 2
hours prior to immunisation (birds drinking behaviour varies, depending on the
air temperature, type of birds, breed, management, weather conditions).
• The drinking system should be clean, without traces of chlorine, other
disinfectants or impurities.
• If needed, turn the lights down low when the water is turned off. After the
vaccine is in the drinking system, increase light intensity again. Increased light
intensity will stimulate the birds to look for food and water.
• Always make sure that there is food available when vaccinating. Birds will not
drink if they have no food to eat.