Halting in ovo vaccination not a good option for managing hatchery bacteria

Higher 7-day mortality from bacterial infections in the hatchery is no reason to stop in ovo vaccination for Marek’s and other diseases, according to a consulting poultry veterinarian.

Punching a hole into an egg to deliver a vaccine at a time when most poultry companies have stopped using antibiotics in the hatchery increases the risk for bacterial infection, conceded Guillermo Zavala, DVM, PhD, formerly of the University of Georgia and founder of the consulting firm Avian Health International, LLC.

However, live production needs to consider the big picture. “We always have to keep in mind that the only profit center for this industry…is the processing plant,” Zavala told Poultry Health Today.

Producers not using antibiotics in the hatchery might see a slight benefit in 7-day livability if they stop in ovo vaccination against Marek’s. “But then the end result is really what counts — and that’s the economic mission of the company. It’s not 7-day livability. That’s not what we sell,” he said.

Remember immunosuppression

It’s also important to remember that Marek’s disease is not only a disease that causes tumors, it can lead to severe immunosuppression, he continued.

“If you don’t vaccinate your birds against Marek’s disease, you’re automatically opening the door for immunosuppression and complications with bacteria and viruses, and making it difficult for your [other] vaccines to operate the way they should,” Zavala said.

Producers raising broilers without antibiotics especially need to vaccinate against Marek’s disease, he continued, because they are more susceptible to a variety of diseases.

From a practical standpoint, the efficiency of in ovo vaccination is difficult to ignore when vaccinating millions of broilers a week for Marek’s disease. “We have to operate with mass-application systems,” he added.

“Again, I think the right strategy is not to abandon Marek’s vaccinations,” he said. The better alternative is to go back to basics.  Work with very clean eggs and have good hatchery sanitation and proper incubation conditions.

“Everything starts at the breeder level, not necessarily at the broiler level as many people think it would. It’s a very comprehensive process,” Zavala noted.