Differences in protection between heavy and light breeds of chickens following vaccination with Newcastle disease vaccines-a survey of data, 1971 to 1990.
Data obtained over 20 years of Newcastle disease vaccine testing were statistically analyzed. The protection afforded heavy and light breeds of chickens was compared following challenge (efficacy) after vaccination with live and inactivated vaccines produced from different virus strains. Standard challenge virus was used throughout the period. The data show that the heavy breeds were significantly inferior in their protectability when compared with the light breeds. This inferiority was shown after vaccination with all types of vaccines. It is suggested that heavy and light breeds of chickens differ genetically in their acquired resistance to Newcastle disease virus, although difference in susceptibility to the virus as a pathogen cannot be ruled out entirely.
Samina
I
I
State Laboratory for Vaccine Control, Kimron Veterinary Institute, Bet-Dagan, Israel.
Brenner
J
J
Peleg
B A
BA