REPLICATED DIVERGENT SELECTION OF BROILER-CHICKENS FOR HIGH OR LOW EARLY ANTIBODY-RESPONSE TO ESCHERICHIA-COLI VACCINATION

Four sublines of broiler chickens were selected from a base population for three generations for high or low antibody response to vaccination with Escherichia coli at 10 days of age. Two sublines were selected for a high response (HC) and two for a low response (LC). Realized heritability estimates over three generations of selection for each pair of replicated lines averaged .23 in HC lines and .32 in LC lines. No correlated response in the important production trait, body weight at marketing age, was observed. The ability to survive pathogenic E. coli challenge with or without prevaccination showed no differences between the lines in the unvaccinated chicks, although following vaccination there was higher mortality and morbidity in the LC lines. These data suggest that the use of antibody response in young chicks to E. coli vaccine may be a useful genetic indication of more general disease resistance.