Tags: Chick handling | Whitepaper
11 September 2014,
Spray vaccination is the preferred method for administering respiratory vaccines, eg. for Newcastle Disease (ND) or Infectious Bronchitis (IB), especially when vaccinating birds for the first time.
Spray vaccination can be undertaken either in the hatchery or immediately after reception at the farm, while the chicks are still in boxes. Vaccinating in the hatchery is generally considered more effective, as the process is automated and therefore more controlled than the hand-spraying that tends to occur on the farm. Hatchery automated methods include either the use of a spray cabinet that is triggered each time a box of chicks is placed inside, or a spray vaccinator mounted over the conveyor line for chick boxes.
Vaccines suitable for spray delivery are live vaccines, produced by growing the required virus in incubated eggs or tissues cultures. After attenuation (=weakening), the viruses are freeze-dried and appear as a pellet in a glass vial containing 1,000 - 10,000 doses. This allows the vaccines to be stored under controlled conditions for several months until expiry date.
Prior to use, the vaccine is dissolved in water, after which it expires within hours and therefore must be used immediately. The water serves as a transport medium for the live virus to the day-old-chicks. Once sprayed, the vaccine will attach to the mucosa cells of the chicks’ eyes and upper respiratory tract. Preening (= cleaning feathers with beak) optimises uptake. Once in the body, the virus will multiply inside the mucosal cells, to develop good local immunity in the respiratory tract.
When administering vaccines by this method, it is important that the spray is ‘coarse’, ie. that droplets are at least 100 - 150 microns in size. Any smaller and the vaccine will be inhaled too deeply into the respiratory tract, resulting in an excessive post-vaccination reaction. This presents as mild disease symptoms in the flock 3- 5 days after vaccination - and will have a negative effect on production.