Vaccines are a critical baseline of defense for flock health. Science and nature are constantly evolving, and so must the methods with which vaccines are stored and administered. Other factors that impact the process include the vaccine target and the age of the birds.
At the Hatchery
At the hatchery, there are two options for vaccine timing; in-ovo (embryonic developmental day 18 to 19,) or the day of hatch. To inoculate birds at transfer, killed or inactivated viruses or bacteria are injected into the air sack of the egg. The efficiency of the in-ovo vaccination process has improved throughout the years with the introduction of machines to inject a whole tray of eggs simultaneously. Eggs must be trayed properly with the air sack facing up. Malposition eggs will not be vaccinated correctly resulting in lack of vaccine efficacy or even embryonic death.
At hatch, chicks may be vaccinated with a subcutaneous injection or a vaccine delivered as a spray. Spray vaccine uptake may vary for each target. For example, coccidiosis vaccines may be sprayed in a mist or gel directly onto the birds for preening and digestion, while bronchial sprays need to be inhaled to reach the respiratory tract and be effective.