The immune response of hens to multiple Escherichia coli injections and transfer of immunoglobulins to the egg and hatched chick.

Four spaced E coli antigen injections were given to laying hens in order to cause an extended period of antibody production. Antibody could be detected as early as four days after the first antigen injection reaching a peak at the 20th day. IgM was the first antibody to be detected. From the eighth day IgG could be detected replacing the IgM fraction gradually. Antibody to E coli produced by the hen could be detected in yolk of eggs and in chicks from the 15th day but not after the 87th day post treatment. Fluctuation or antibody transmitted by the individual hen was observed. Yolk and chick antibody titres were slightly lower than those found in the serum of the hens on the same day. Only IgG antibodies were found in yolks and serum of day-old chicks.