Immunoglobulin M associated with secretory component and immunoglobulin A deficiency in bovine colostrum

Immunoglobulin (Ig) M purified from bovine colostrum was examined by an immunodiffusion analysis with antisecretory IgA serum and was found to be associated with a secretory component. Some of the combined proteins were dissociated if treated with 5 M guanidine-HCl and others were not. Another immunodiffusion analysis of 23 specimens of colostrum led to the finding that certain colostrums were deficient in IgA, even though they contained IgG and IgM.