[Experiments with the simultaneous or combined vaccination of chicks against Marek's disease and Newcastle disease]

Simultaneous vaccination was carried out of day-old chicks against Marek's disease (strain C3--1) and Newcastle disease (strains B1 and La Sota) which did not prove to be effective in conferring a lasting immunity to Newcastle disease though it was tolerated without any disturbances whatever. One could resort to it by way of an exception only, with an obligatory revaccination 15 days later, when the unfavourable epizootic status made it necessary. The immunity built up against Marek's disease did not seem to be affected by the simultaneous or succeeding vaccination against Newcastle disease with live lentogenic strains. Effective in conferring solid immunity against Newcastle disease proved the combined application of the two vaccines in the following order: treatment of day-old chicks with a vaccine against Marek's disease and vaccination of the same chicks at the age of 8 days with a vaccine against Newcastle disease (strain B1) at a half rate, employing the spray method, followed by revaccination 15 days later with the La Sota vaccine at a full rate, employing the aerosol method.