It is customary to vaccinate poultry that is raised for commercial purposes against various respiratory diseases such as Newcastle's Disease and infectious brochitis. Usually the birds are vaccinated when they are ten to twelve days old, after they have been moved from the hatchery to the brooder house.
Some of the methods used to vaccinate baby chicks have been to physically inject vaccine into the body of the chick with a syringe, to spray live virus vaccine into the mouth of a chick as the upper beak is foreshortened in a "de-beaking" process, and to place a drop of vaccine with an "eye dropper" into an eye of the chick so that the vaccine enters the eye opening of the chick and passes through the nasal passage of the chick and into the respiratory system. These procedures require the chicks to be handled individually and require a long time for a person to administer vaccine. Also, the spraying of vaccine into the mouth of a chick sometimes results in secondary bacterial infections in the lungs of the chick and causes lung disease and death. Another method of vaccination is to mix vaccine with the drinking water for chicks. This has proven to be about fifty percent effective in properly administering the vaccine to the chicks. Another method of vaccinating chicks that was used for a short duration was to place a multiple number of the chicks in a container and form a fine mist of liquid live virus vaccine in the container about the chicks so that the chicks inhaled the vaccine. This method of vaccinating chicks resulted in excessive vaccine reaction of the chicks and caused lung disease and death of a substantial percent of the chicks.