Simultaneous vaccination of one-day-old broiler chickens with tenosynovitis virus and turkey herpesvirus.

An attenuated tenosynovitis virus vaccine and turkey herpesvirus (HVT) vaccine mixed prior to vaccination were injected subcutaneously into one-day-old chicks. In laboratory and field trials there did not appear to be any interference, because chickens vaccinated with both vaccines were effectively immunized against challenge with virulent Marek's disease virus or tenosynovitis virus when compared with unvaccinated chickens or chickens vaccinated with either HVT or tenosynovitis virus. The combined tenosynovitis and HVT vaccine had essentially the same virus titers when compared to the titers of each vaccine prior to mixing. Also, the HVT viremia levels and the serum neutralization titers of chickens vaccinated with both vaccines were essentially the same as those in chickens vaccinated with a single vaccine. In field trials, chickens vaccinated with the combined vaccines had fewer condemnations for parts and septicemia-toxemia and total condemnations when compared to chickens not vaccinated with tenosynovitis virus. There was less mortality in the majority of the flocks vaccinated with tenosynovitis virus vaccine and HVT when compared to flocks receiving only HVT vaccine.