The Occurrence of Natural Antibodies to Rumen Bacteria

SUMMARY: The sera of II ruminants and one horse contained relatively high titres of agglutinating antibodies against strains of anaerobic bacteria isolated from the bovine rumen. They were not detected in the sera of non-ruminants, i.e. pig, rabbit, guinea pig, rat and man. A close relationship existed between motility of rumen organisms and their ability to evoke detectable antibodies, although antibodies to both flagellar and somatic antigens were produced. The antibodies to the rumen organisms were highly specific and of the IgM type. They occurred in bovine colostrum at the same level as in the blood serum, and were transferred to the calf via the colostrum. After 1 month they had disappeared from the calf serum but between 5 and 8 months later antibodies of a similar activity were detected. In addition, antibodies to the non-motile Bifidobacterium bifidus were found in the sera of the young calf.