Genetic and phenotypic correlations between immune response to Escherichia coli and to Newcastle disease virus vaccines.

Genetic and phenotypic variation and covariation in immune response to inactivated Newcastle disease virus (NDV) vaccine and to Escherichia coli vaccine were studied in commercial poultry strains. Within any given experiment there was no tendency for individual birds to respond in a correlated manner to NDV and E. coli vaccines. There were highly significant differences between sire families in immune response to NDV vaccine (57 sire families) and to E. coli vaccine (35 sire families). Heritabilities of immune response levels to NDV and to E. coli were .41 and .25, respectively. In both cases, additive genetic standard deviations were slightly over 1.0 titer unit. The correlation between sire-family means for response to NDV and sire-family means for response to E. coli (35 sire families) was .077 and statistically nonsignificant. Thus, the data provide evidence for the presence of significant genetic variation in immune response with respect to two endemic disease antigens, but they provide no evidence for a genetic correlation in response to the two antigens.