The German Regulation on
Fowl plague which is in force since 1994 laid down that any chicken of all races and all hybrids must be vaccinated against
Newcastle disease (ND) in a mode that an adequate immunity is achieved. Onset, duration, and resistance to challenge of immunity induced by vaccination is well documented in the scientific literature for hybrid chicken of the layer and meat types. These data prove also innocuity and efficacy of the registered
vaccines. In contrast, only a few and incomplete data exist on the development of ND directed immunity in fancy chickens. The present study describes vaccinations of chickens of 14 different hobby breeds with live LaSota
vaccine (conjunctival application of 10(6) embryo-infective dose50 per bird) and with an inactivated oil-
emulsion vaccine (intramuscular application of 0.5 ml per bird) and subsequent intramuscular challenge
infections using the highly virulent NDV strain Herts 33/66. Chickens of all 14 breeds tolerated the application of both
vaccines. All fancy chickens reacted with the production of serum
antibodies which were measured in the haemagglutination inhibition (HI) and virus neutralisation (VN) tests. According to the scientific literature, maximal antibody levels are reached in hybrid chickens between day 10 and 20 post vaccination. In contrast, in fancy chickens the antibody maxima are delayed to the seventh to eighth week post vaccination. All fancy chickens vaccinated either once with live LaSota virus or with live and
inactivated vaccines resisted challenge with the highly virulent Herts 33/66 strain of NDV and did not develop any signs of disease. There are indications for gradual differences in susceptibility of different breeds of fancy chickens. The levels of non-specific neutralisation as measured in the virus neutralisation test differ between breed. Also, the viral content in tissues obtained from non-vaccinated but challenged birds differ markedly. It is concluded from the results of this study that fancy chickens can also successfully protected against
Newcastle disease by using live and
inactivated vaccines which are licensed for hybrid chickens. However, the optimal time for the detection of maximal antibody levels in fancy chickens is reached seven to eight weeks post vaccination.