Antibody responses to sheep red blood cell and Brucella abortus antigens in a turkey line selected for increased body weight and its randombred control

Turkeys from a randombred control line (RBC2) and its subline (F) selected for increased 16-wk BW were tested for primary and secondary antibody respo nses to SRBC antigen and Brucella abortus antigen (BA). Previous studies ha ve shown that the F line was more susceptible to Pasteurella multocidia and Newcastle disease virus than was the RBC2 line. Individuals from the RBC2 and F lines were intravenously injected with 1 mt 5% SRBC antigen or 0.1 mL undiluted BA at 4 and 6 wk of age; blood samples were collected at 0, 4, 7 , and 10 d post-immunization. Total, IgG, and IgM titers were measured by a gglutination assays. Compared with the RBC2 line, the F line had generally higher total anti-SRB C titers; the differences were significant at 14 d postprimary immunization (PPI) (females); at 10 d postsecondary immunization (PSI) (males); and at 4, 7,and 10 d PSI (females) (P less than or equal to 0.05). The F line also had higher IgM titers at 14 d PPI (females) and at 10 d PSI (males) (P les s than or equal to 0.05). For IgG titers, a line difference was evident in females at 4 and 10 d PSI (P less than or equal to 0.05); the F line had hi gher titers than did the RBC2 line. For the antibody response to BA in male s, the F line had lower total and IgM titers at 10 d PPI (P less than or eq ual to 0.05) than did the RBC2 line. No significant line differences in res ponse to the BA were found in total and IgM titers in female turkeys or in IgG titers in both sexes at any time. These results suggest that selection for fast growth rate of turkeys might have resulted in changes in humoral i mmunity to the SRBC antigen and BA.