Serological changes in immunoglobulins IgG, IgA and IgM and Escherichia coli antibodies in the young pig.

The variation in serum levels of immunoglobulins IgG, IgA and IgM has been studied during the early development of the young pig using radial immunodiffusion assays with specific rabbit antisera. Antibodies against 08 and 0141 were assayed by antiglobulin haemagglutination and bactericidal techniques. Bactericidal activity could be measured in pre-colostral piglet serum and this was partially eliminated by absorption with specific rabbit anti-IgG-globulin serum. This activity was associated with an IgG component identified in low molecular weight protein fraction isolated from Sephadex G-200. Immunoglobulins IgG, IgA and IgM acquired from the colostrum began to decline after the first day. Antibacterial antibodies were mainly associated with IgM and these declined rapidly in the 1st week of life with an apparent half-life of 1.3 days. Levels of IgM increased after the first week but IgA and IgG continued to decline with no evidence of an increase in serum level until about the 4th week. In colostrum deprived pigs, serum levels of IgA and IgG increase from birth but IgM could not be assayed before the 3rd week.