Precision in Poultry Vaccination: Protecting Flocks adn profits
Even slight inaccuracies in in ovo vaccine delivery – as small as a millimeter – can drastically reduce a chick’s immune response, leaving poultry flocks vulnerable to disease despite vaccination. According to Dr. Josh Deines, Technical Service Device Lead at Zoetis, “Vaccination accuracy is one of the biggest determining factors of whether a vaccine is going to stimulate an immune response and therefore provide protection to that bird for the targeted diseases.” The location of vaccine delivery within the egg is critical to its effectiveness.
Accurate placement in the embryo body or amniotic fluid can yield over 93% protection against targeted diseases. However, misdirected injections – into the allantois, for example – reduce protection to 28% or less, while injections into the air cell offer virtually no protection.
Several factors can compromise in ovo vaccination accuracy. Common issues include bent needles, which redirect vaccine placement. Routine equipment maintenance is also vital; slipping tooling, often caused by water or sanitizer leakage onto injection heads, prevents stable positioning during injection.
Timing is equally crucial. The optimal transfer window is between 17 days and 12 hours and 19 days and 4 hours of incubation. Injecting too late, as embryos fill the shell, increases the risk of off-target vaccinations. Early transfer or inconsistent incubation temperatures can lead to abnormally developed embryos, also increasing the risk of improper vaccine placement.
Fortunately, a thorough quality control (QC) checklist can substantially improve consistency. This includes regularly running QC plates (as recommended by the technology manufacturer) to verify proper vaccine deposition, visually inspecting injection tooling at a 45-degree angle for bent needles, and monitoring for slipping tooling throughout the process.
Maintaining a controlled habitat is also crucial. Hatchery managers should ensure embryos are transferred into clean, dry, and appropriately temperature-controlled baskets, and protect injection equipment from water leaks and excessive humidity.
“There’s no reason not to do it,” emphasizes Dr. Deines. “It’s such an easy task requiring little time and it can significantly impact results.” For hatcheries processing millions of chicks each month, even small improvements in vaccination accuracy can translate into significant economic gains.
