Genetic analysis of antibody responses of turkeys to Newcastle disease virus and Pasteurella multocida vaccines.

Heritability (h2) of 16-wk BW and primary and secondary antibody responses and genetic and phenotypic correlations among these traits were estimated for 931 male and female turkeys vaccinated with Newcastle disease virus (NDV) and Pasteurella multocida. Turkeys from a line selected for 22 or 23 generations for increased 16-wk BW were vaccinated at 6 and 12 wk of age with blood samples collected 3 wk postvaccination. Antibody titers were determined using an ELISA method and transformed to log(e) for analysis. Heritability estimates for primary and secondary antibody responses to NDV were .380 +/- .070 (SE) and .296 +/- .063, respectively. For primary and secondary antibody responses to P. multocida, h2 estimates were .458 +/- .075 and .333 +/- .066, respectively. Heritability estimate for 16-wk BW was .404 +/- .071. The genetic correlation between primary and secondary antibody responses to NDV was .491 +/- .150. There was no genetic correlation between primary and secondary antibody responses to P. multocida. Although the genetic correlation between primary antibody responses to NDV and P. multocida was .292 +/- .159, the genetic correlation between secondary responses to the two antigens did not differ from zero. There were no genetic correlations between antibody responses and 16-wk BW. Similar results were observed for phenotypic correlations. Based on heritability and genetic correlation estimates, it would be possible to improve antibody responses to either NDV or P. multocida singularly; however, to improve antibody responses to both antigens, selection would have to be applied for each antigen.