For administration to broiler chickens via the drinking water from two weeks of age when maternal antibody levels have declined to a low level.

1. Make sure that all conduit pipes, tubing, troughs, drinkers etc are thoroughly clean and free of any trace of disinfectants, detergents, soap, etc.

2. Allow water to be consumed so that levels in drinkers are minimal before vaccine is applied. If water is still present, drain lines before applying vaccine. Apply vaccine over up to 3 hours, ensuring that all birds drink during this time. Birds drinking behaviour varies. It may be necessary to withhold water on some sites prior to vaccination in order to ensure that all birds drink during the vaccination period. The aim is to give every bird one dose of vaccine.

3. Water used for drinking water administration of a live virus vaccine must be non-chlorinated and contain as few as possible metal ions. This can be achieved by allowing mains water to stand for 12 hours or by use of deionised water. The addition of milk powder is recommended where this is not possible.

4. Open the vaccine ampoule under water and dissolve thoroughly. As the concentrated vaccine is slightly viscous, care should be taken to empty the ampoule and its top completely by rinsing them in water. Then thoroughly dissolve in a 1 litre jug and stir well before mixing with more water in a two gallon bucket before application. Vaccine must be stirred thoroughly for several minutes at each stage. Do not split large vials to vaccinate more than 1 house or drinking system, as this leads to mixing errors. Apply diluted vaccine to cold and fresh water at the rate of 1,000 doses of the vaccine to 1 litre of water per day of age for 1,000 chickens, eg 10 litres would be needed for 1,000 10 day old chickens.

Low-fat skimmed milk powder (ie <1% fat) may be added to the water (2-4 grams per litre) or skimmed milk (1 pint per 5 gallons of water) to increase the stability of the virus.

All tubing should be emptied of plain water, so that the drinkers contain only vaccine water. Ideally vaccine should be administered in the volume of water consumed by the birds in up to 3 hours. If in doubt, measure water intake the day before administering vaccine.

5. Administer the dissolved vaccine to birds immediately after dilution.

6. Avoid exposure of the vaccine suspension to sunlight.