The effects of passive antibodies to egg albumin on active immunity in lambs to Brucella abortus and egg albumin.

The long-term effects of colostrum on active immunity to two unrelated antigens are described. Lambs were fed with pooled colostrum--to equalise passive immunity--with or without added antibodies to egg albumin (Ea). There were significant breed differences in the response both to Brucella abortus measured at one month of age, and to Ea, measured at three months of age, although there was no significant correlation between the responses to the two antigens, either within or between breeds. Surprisingly, whereas antibodies to Ea caused a four-fold reduction in antibody production to B abortus, they did not affect the overall mean response to Ea. But the timing of the response to Ea was significantly affected, suggesting that the low persisting concentrations of antibody had caused qualitative changes in the response.