Vaccination against avian encephalomyelitis with special reference to the spray method.

Three vaccination methods against avian encephalomyelitis have been tested in different types of housing. The product used was a vaccine improved by Philips-Duphar, having an optimal disseminative and immunogenic capacity, and a high virus titer per bird dose. We have tested: 1) administration per os in 2-5% of the flock, 2) administration via drinking water in the whole flock and 3) spray vaccination. Observations by Schneider (1967), that administration in the beak in part of the animals may only be satisfactory under optimal conditions, have herewith been confirmed. With the actual rearing on batteries, the chance of horizontal spreading of the vaccine virus is minimal. The two other methods of administration eliminate this problem. Already 3 weeks after vaccination more than 50% of the animals show a positive serological reaction. Later this level increases quickly to more than 80%, even in batteries. Under widely varying circumstances (concentaration of animals, ventilation, length of water tubes, etc) a dosage response effect becomes apparent. The practical results obtainable will be dependent on the titer of the vaccine, care while vaccinating and conditions of housing.