Target species
Chickens (Broilers)
Indications for use
For active immunisation of broilers with insignificant levels of maternally derived antibodies (ELISA of 500 or below) to reduce mortality, clinical signs and bursal lesions of Gumboro disease. Such birds can be vaccinated from one day of age. The onset of immunity is 14 days post vaccination and the duration 43 days post vaccination.
Contra-indications
Do not vaccinate sick birds.
Do not use in infected flocks showing clinical signs.
Since no studies to demonstrate the safety of this vaccine when it is administered to layers and breeders have been carried out, its use is not recommended for these categories of the target species.
Special warnings for each target species
Use only in flocks with low levels of maternal antibodies (mean ELISA titres 500). The optimum day of vaccination of broilers with maternal antibodies is calculated according to the Kousenhoven's formula (see section posology).
Due to its residual pathogenicity to the bursa the vaccine should be used only in areas contaminated with vvIBDV, except for infected flocks showing clinical signs.
Special precautions for use in animals
•Do not use water with chlorine or disinfectants to reconstitue the vaccine.
•The vaccine strain spreads to un-vaccinated chickens.
•Appropriate veterinary and husbandry measures should be taken to avoid spread to susceptible species.
Special precautions to be taken by the person administering the veterinary medicinal product to animals
•Wash and disinfect hands and equipment after use.
•In the case of accidental ingestion, contact with the eyes, or spillage onto the skin seek medical advice immediately and show the package leaflet or the label to the physician.
Adverse reactions
The administration of a single dose causes lymphocyte depletion in the bursa of Fabricius (in 50-75% of the follicles). Lymphocyte repopulation is observed from 14 days post vaccination onwards, at 28 days post vaccination there is still some depletion remaining (5-25% of follicles). This lymphocyte depletion does not result in an immuno-suppressive effect.
Use during pregnancy, lactation or lay
Do not use in layers and breeders.
Interactions
No information is available on the compatibility of this vaccine with any other. Therefore the safety and efficacy of this product when used with any other (either when used on the same day or different times) has not been demonstrated.
Amounts to be administered and administration route
Break the vacuum inside the vial by inoculation of 10 ml of drinking water without chlorine or disinfectants. Shake gently until complete resuspension of the freeze-dried powder before administration.
Posology
Serologically negative birds can be vaccinated from one day of age. The optimum age for vacciantion may be calculated using the level of maternal antibody in the chicks at day old (Kouwenhoven's formula) by testing at least 18 birds (preferably 24) of the flock according to the following table. All birds should be given a single vaccination only.
MEAN ELISA TITRE AT 1 DAY OF AGE | OPTIMUM AGE FOR VACCINATION (DAYS) |
≤500 | 1 |
≤750 | 2-3 |
≤1000 | 4 |
≤1250 | 5-6 |
≤1500 | 7 |
≤2000 | 9 |
≤2500 | 11 |
≤3000 | 12-13 |
≤3500 | 14 |
≤4000 | 15-16 |
≤4500 | 17 |
≤5000 | 18 |
≤5500 | 19 |
≤6000 | 20 |
Method of administration
The volume of water for reconstitution depends on the age of the birds and the management practice. Generally, 2 litres of water per 1,000 broilers for every day of age are needed. Hence, 1,000 14 day broilers would need 28 litres of water to reconstitute the 1,000 doses of vaccine. If the birds have higher or lower water requirements, adjust the volumes accordingly.
The way in which this vaccine is administered is critical. The following management consideration have been found to improve the vaccine intake:
Water should be withheld for 1-2 hours before vaccination to ensure that all reconstituted vaccine is consumed within 1-2 hours.
For bell drinkers: go round the house emptying and cleaning the drinkers during the water withholding period. Mix up the vaccine according to the recommendations and at the end of the water withholding period go round all the drinkers and fill them with water containing vaccine.
For nipple drinkers: a considerable amount of residual water may remain in the lines after the water withholding period. It is recommended to drain the lines and load them with water which contains vaccine before allowing the birds to have access to the nipples. Mix up the vaccine and apply to the tank. Calculate the volume that is left in the tank below the outlet valve and be sure to take this volume of water into account when calculating the number of doses to be added.
Always make sure that there is food available when vaccinating (birds will not drink if they have no food to eat). Turn on mains water when all the water containing vaccine has been consumed.
Overdose
The administration of a 10 fold dose causes lymphocyte depletion in the bursa of Fabricius (in approximately 75% of follicles). Lymphocyte repopulation is observed from day 14 onwards and by day 28 post vaccination less then 25% of follicles are affected.
Withdrawal periods
Zero days.