Target species
Chickens
Indications for use
For the active immunisation of chickens against Infectious Bursal Disease (Gumboro).
Contraindications
The vaccine should not be used in birds without maternally derived antibodies. Spread of the vaccine strain to such birds should be prevented.
Special warnings for each target species
A good immune response is reliant on the reaction of an immunogenic agent and a fully competent immune system. Immunogenicity of the vaccine antigen will be reduced by poor storage or inappropriate administration. Immunocompetence of the animal may be compromised by a variety of factors including poor health, nutritional status, genetic factors, concurrent drug therapy and stress. Under certain conditions, for example extreme disease pressure and variant challenge, fully immune birds may succumb to disease. Therefore, successful vaccination may not be synonymous with full protection in the face of a disease challenge.
Special precautions for use
Only healthy birds should be vaccinated.
Operator warning
Wash and disinfect hands after use.
Adverse reactions
The vaccine may cause a transient lymphocyte depletion in the bursa of Fabricius. This does not result in a significant immunosuppressive effect when used in chickens with maternally derived antibodies (MDA).
Use during pregnancy or lactation
Do not vaccinate birds in lay.
Interactions
No information is available on the safety and efficacy of this vaccine when used with any other veterinary medicinal product. A decision to use this vaccine before or after any other veterinary medicinal product therefore needs to be made on a case by case basis.
Amounts to be administered and administration route
The vaccine is administered in the drinking water.
Reconstitution of vaccine
The vaccine may be delivered as a freeze-dried cake in a glass vial or as freeze-dried spheres in cups. In case of the latter presentation the cups may contain 3 up to 400 spheres depending on the required dosages and production yields. In case of the product presented in cups, do not use the product if the contents stick to the container as this indicates that the integrity of the container has been breached. Each container should be used immediately and completely after opening.
The vials should be opened under water or the content of the cup(s) should be poured into the water. In both cases mix the water containing the vaccine well before use. After reconstitution the suspension looks clear. Measure the correct volume of water for the number of birds to be vaccinated (see below). All containers used should be clean and free from any traces of detergent or disinfectant. Mix thoroughly with a clean stirrer, ensuring that all vials used are emptied. Offer to birds immediately.
For reconstitution, use clean cold water, in which chlorine or metals can neither be tasted nor smelled. Where water sanitisers are used consult Intervet technical staff. Chlorine at levels as low as 1 ppm is known to have a detrimental effect on vaccine virus stability, therefore the use of liquid skimmed milk is recommended to prolong the life of the virus. This may be added to the water at the rate of 500 ml (approximately 1 pint) per 10 litre of water. After mixing well, the solution should be allowed to stand for 15 - 30 minutes before adding the vaccine. Only skimmed milk should be used, as the fat in whole milk may block the automatic drinking systems as well as reduce vaccine virus efficacy.
Volumes of water for reconstitution of vaccine
The volume of water for reconstitution depends on the age of the birds and the management practice.
Simple drinking troughs and fountains
The following are guidelines:
1000 doses per litre per age in days up to a volume of 20 litre per 1000 doses.
For heavy breeds, or in hot weather, the quantity of water may be increased up to 30 litre per 1000 doses. Where the number of birds is between the standard dosages, the next higher dosage should be used.
Nipple Drinkers
Drinker line management is known to have a significant effect on the viability of live vaccine virus. The vaccine virus can deteriorate very rapidly and it is essential to ensure that all birds received the correct dose. Special care should be observed concerning the method of administration. For example, small header tanks may require recharging with medicated water several times during a 1 - 2 hour period.
Vaccination programme:
Birds, which should be at least 10 days of age, should be given a single vaccination. The optimum age for vaccination may be calculated using the level of maternal antibody in the chicks at day old (Kouwenhovens formula), but normally lies in the range 12 - 18 days. Further information is available from Intervet technical staff.
Administration:
Water should be withheld before vaccination. For recommendations see below under Management. Ensure that all medicated water is consumed within 1 - 2 hours. Turn on mains water when all the vaccine water has been consumed. Always make sure that there is food available when vaccinating. Birds will not drink if they have no food to eat.
Management:
Great care should be taken to ensure that all birds receive a full dose of vaccine when the product is administered. When used in chickens where maternal antibody still exists, the way in which this vaccine is administered is critical. The following points have been found to improve vaccine "take":
1Water withholding should be kept to a minimum, especially in broiler birds. Approximately half an hour is all that is required if the following management techniques are used.
2Try to vaccinate at a time when birds are likely to be drinking, e.g. morning time for broilers, when food is in the food tracks.
3Turn the lights down low when the water is turned off. For bell drinkers, go round the house emptying and cleaning the drinkers during the half-hour lights low period. Mix up the vaccine according to the recommendations, and towards the end of the half-hour water withholding period, go round all the drinkers filling each with water containing vaccine. Leave the house and turn the light up. The increased light intensity will stimulate the birds to look for water and food. Therefore, it is important that food is available or the birds will not be interested in drinking. In some cases, it helps to run food tracks at the time the light intensity is increased.
4For nipple lines a substantial volume of residual water may remain in the lines after the half-hour water withholding/dark period. It is advisable to drain the lines and prime with vaccine loaded water before allowing the birds to have access to the drinker lines. Mix up the vaccine and apply to the header tank(s). Calculate the volume of water that is left in the tank below the outlet valve and make sure you add extra vaccine to this volume of water. For example, if 10 litre remain below the outlet pipe and you are using 10 litre/1000 birds to vaccinate, add one extra vial of vaccine when mixing up vaccine for that tank. The use of this extra vaccine is important.
5Once the vaccine has been consumed, resume management practices as normal. This approach to vaccination will ensure a more even vaccination of the crop and will be less stressful to the birds. Performance should therefore be less adversely affected.
Overdose
No particular symptoms at ten times dose.
Withdrawal period
Zero days.