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 respo nses and genetic and phenotypic correlations among these traits were e stimated for 931 male and female turkeys vaccinated with Newcastle dis ease virus (NDV) and Pasteurella multocida. Turkeys from a line select ed 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 seconda ry antibody responses to NDV were .380 +/- .070 (SE) and .296 +/- .063 , respectively. For primary and secondary antibody responses to P. mul tocida, h2 estimates were .458 +/- .075 and .333 +/- .066, respectivel y. Heritability estimate for 16-wk BW was .404 +/-.071. The genetic co rrelation between primary and secondary antibody responses to NDV was .491 +/- .150. There was no genetic correlation between primary and se condary antibody responses to P. multocida. Although the genetic corre lation 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 corre lations between antibody responses and 16-wk BW. Similar results were observed for phenotypic correlations. Based on heritability and geneti c correlation estimates, it would be possible to improve antibody resp onses to either NDV or P. multocida singularly; however, to improve an tibody responses to both antigens, selection would have to be applied for each antigen.