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Studies demonstrate benefits of dual-needle in ovo vaccination for Marek's disease

Building on a 60-year legacy, Zoetis presented more than 20 papers and posters at the recent World Veterinary Poultry Association (WVPA) conference held in Nantes, France, and the American Association of Avian Pathologists (AAAP) conference in Chicago. Here are summaries of a few key presentations, all based on research aimed at discovering practical solutions for improved poultry health. For more news reports from AAAP and WVPA, visit poultryhealthtoday.com.

In a challenge study believed to be the first of its kind, chickens vaccinated in ovo with a dual-needle delivery system were better protected from Marek's disease than those receiving the same vaccine with a conventional single-needle in ovo delivery system.

In a US study, broiler eggs were equally divided and injected at 18 days of incubation with a herpesvirus of turkey (HVT) vaccine, commonly used by the broiler industry to protect against Marek's disease. Half the eggs were vaccinated using the Embrex® Inovoject® dual-needle system, and for the other half, a single-needle system was used.

At 3 days of age, investigators challenged both groups of vaccinates with the RB1B strain of Marek's disease virus and then evaluated the birds for 7 weeks, Taylor Barbosa, DVM, MS, PhD, ACPV, director of outcomes research, Zoetis, said at the WVPA conference.

The level of protection, determined by the absence of tumors, was significantly better in birds from the dual-needle group compared to the single-needle group and a group of unvaccinated controls. "This indicates that with the dual-needle system, the delivery of the vaccine was correct and allowed for better replication of vaccine virus," Barbosa said.

The dual-needle group also had better weight gain (Figure 1), he said.

"To our knowledge, this was the first study that employed a viral challenge to compare the efficacy of in ovo vaccine application devices for delivery of an HVT vaccine," he commented.

Barbosa also presented results from two field studies conducted at commercial broiler hatcheries in Brazil, where the dual-needle in ovo system resulted in better Marek's disease vaccine coverage compared to subcutaneous vaccine administration at 1 day of age.